Patent Publication Number: US-3875151-A

Title: Process for the manufacture of amino-compounds

Description:
United States Patent Fechtig et a1.  
 1 1 *Apr. 1, 1975 l l PROCESS FOR THE MANUFACTURE OF AMINO-COMPOUNDS [75] Inventors: Bruno Fechtig, Reinach; Ernst Vischer. Basle; Hans Bickel, Binningen, all of Switzerland; Rolf Bosshardt, deceased, late of Basle, Switzerland; by Ruth Elisabeth Bosshardt-Schar, legal representative, Arlesheim, Switzerland; Jacob Urech. Basle, all of Switzerland [73] Assignee: Ciba-Geigy Corporation, Ardsley,  
 [ Notice: The portion of the term of this patent subsequent to Oct. 10, 1989, has been disclaimed.  
 [22] Filed: Oct. 2, 1972 [21] Appl. No.: 293.906  
 Related US. Application Data [63] Continuation of Scr. No. 200,511, Nov. 19. 1971, Pat. No. 3,697,515. which is a continuation of Scr. No. 842,359, July 16. 1969. abandoned, which is a continuation-in-part of Ser. No. 493223, Oct. 5. 1965. abandoned, which is a continuation-in-part of Scr. No. 344,803, Feb. 14, 1964, abandoned.  
 [30] Foreign Application Priority Data Feb. 18. 1963 Switzerland 1992/63 Mar. 1, 1963 Switzerland 2675/63 Apr. 3. 1963 Switzerland 4249/63 June 13, 1963 Switzerland 7358/63 UNITED STATES PATENTS 3,499,909 3/1970 Weissenburger et a1. 260/243 X 3,575,970 4/1971 Weissenburger et a1. 260/243 3.697.515 10/1972 Fechtig et a1. 260/243 FOREIGN PATENTS OR APPLICATIONS 1,795,178 8/1972 Germany Primary E,\&#39;aminerJohn M. Ford Attorney, Agent, or Firnz.1oseph G. Kolodny; John .1. Maitner; Theodore O. Groeger [57] ABSTRACT The present invention is directed to an improved process for splitting the acyl-amino group in bicyclic 3- acylamino-B-lactam type compounds to form the corresponding amino group. It is characterized by formation of an imide halide compound, conversion of the latter into the imino ether and splitting of the C=N double bond of the imino ether.  
 13 Claims, No Drawings PROCESS FOR THE MANUFACTURE OF AMINO-COMPOUNDS CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation application of our application Ser. No. 200,511, filed Nov. 19, 197l (now US. Pat. No. 3,697,515), which in turn is a continuation application of our application Ser. No. 842,359, filed July 16, I969 (now abandoned), which in turn is a continuation-in-part application of our application Ser. No. 493,223, filed Oct. 5, 1965 (now abandoned), which in turn is a continuation-in-part application ofour application Ser. No. 344,803, filed Feb. 14, 1964 (now abandoned).  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a new process for the splitting of the acylamino group in bicyclic 3- acylamino-B-lactam compounds, which contain a thiazacyclic ring fused-on to the dbond ofthe B-lactam ring, to form the corresponding aminogroup, which is characterized in that such a compound is reacted, in the presence of a base, with an agent capable of form ing an imide halide, the imide halide converted into an iminoether by treatment which an alcohol and the C N-double bond of the iminoether is split by treatment with a hydroxy compound.  
  The thiazacyclic ring fused-on to the d-bond of the ,B-lactam ring is fiveor six-membered and its ringnitrogen atom is a ring-member of both, the thiazacyclic and the B-lactam rings, whereas the ring-sulfur atom is directly bound to the 4position of the lactam ring.  
  The bicyclic ring system may, apart from the acyl amino group, contain additional substituents. Thus, the thiazacyclic ring is usually substituted; above all, it contains a carboxyl group, which in the starting material is functionally converted or blocked, and which usually substitutes the carbon atom of the thiazacyclic ring, which is directly bound to the ring-nitrogen atom common to both, the thiazacyclic and the B-lactam rings. Other optional substituents of the thiazacyclic ring, usually bound to the carbon atom adjacent to the one carrying the optionally converted carboxyl group, are lower alkyl. particularly methyl groups, which in turn may be substituted, above all by an csterified hydroxyl group, c.g. a hydroxyl group csterified with a carboxylic acid, for instance an unsubstituted or substituted lower alkanoic acid, such as propionic acid, pivaloic acid. butyric acid, formic acid, chloracetic acid, especially acetic acid, or with an aromatic carboxylic acid such as benzoic or thiobenzoic acid or an aryl lower alkanoic acid such as phenylacetic acid or diphenylacetic acid.  
  The thiazacyclic portion of the bicyclic ring system may be saturated or unsaturated; usually, the fivemembered thiazacyclic ring is saturated, whereas the six-membered analog contains a double bond extending from the ringcarbon atom adjacent to the one bound to the ring-nitrogen-atom, either to the latter or to the ring-carbon atom bound to the ring-sulfur atom.  
  In the acylaminogroup of the starting material the acyl group is the corresponding group of any mono-or dicarboxylic acid. preferably an optionally substituted lower alkanoic acid such as the phenylacetyl or phenyloxyacetyl group, or the y-aminoadipoyl group, in which free functional groups, such as the amino and/or the carboxyl of the &#39;y-aminoadipoyl group, are preferably blocked. Groups useful for the blocking of functional groups, such as the free amino and/or carboxyl groups, occurring in acyl radicals of the acylaminogroup of the starting material are known in the art, especially from the field of aminoacids and peptides. It should, however, be noted, that in the present reaction the whole acyl residue is split off and eliminated, and that, therefore, there is no need to use blocking groups which can be split off after the reaction has been carried out.  
  Useful for blocking an amino group is, for example, a lower alkyl, aryl or acyl radical, advantageously a radical which reduces the basicity of the amino group. The aryl radicals, for example, naphthyl or phenyl radicals, may be unsubstituted or substituted, for example by halogen atoms, nitro, cyano, sulfo, carbamoyl, csterified carboxyl, lower alkylcarbonyl or lower alkoxycarbonyl groups; especially suitable are the 2:4-dinitrophenyl, the 2:4:6-trinitrophenyl, the 2:4-dinitro6- methoxy-phenyl, the 4-cyanophenyl and the 4-carbomethoxy-phenyl radical. Acyl radicals are more especially optionally substituted lower alkanoyl radical with up to 6 carbon atoms, for example acetyl, propio nyl, butyryl, also aroyl radicals, such as benzoyl, as well as benzoyl substituted by nitro, cyano, sulfo groups, halogen atoms, lower alkyl or lower alkoxy groups, and preferably NzN-phthaloyl; furthermore, aryl-lower alkanoyl radicals, such as phenylacetyl, or the carbobenzoxy or tertiary butyloxycarbonyl radical or the benzenesulfonyl or toluenesulfonyl radical may be used for blocking the amino group. The amino groups may also be blocked by protonation.  
  A free carboxyl group may, for instance, be blocked by esterification. As in the case of an amino group occurring in the acyl radical, also a carboxyl group occurring in the acyl radical can beblocked in any suitable way and there is no critical point in this regard as the whole acyl residue is split off in the reaction. Thus, a carboxyl group may be csterified, for example, with an alcohol, such as an unsubstituted or substituted alcohol, furthermore with phenols. In most cases it will be preferred to start with compounds, in which a carboxyl group occurring in the acyl residue is blocked in the same way as a carboxyl group present in the thiazacyclic portion; compounds suitable for that purpose are indicated for illustration below. It is also possible, especially in the case of the y-aminoadipoyl residue, to block the amino and carboxyl group together, for example by reaction with isocyanates or isothiocyanates with formation of a hydantoin or-thiohydantoin ring.  
  In the starting materials of formula I the acyl portion of the acylamino group to be split can be an aliphatic, aromatic, heterocyclic, araliphatic or heterocyclyl aliphatic acid radical, especially the acyl radical&#39;of naturally occurring 7-acylaminocephalosporanic acids and 6-acylamino-penicillanic acid compounds, for example cephalosporin C or -(y-aminoadipoyU-amino penicillanic acid, penicillin G, V, F, dihydro-F, K, X or 0; but may also be any other acyl radical of a carboxylic acid, such as one of those mentioned below.  
  In the preferred starting compounds containing a carboxyl group in the thiazacyclic portion of the bicyclic ringsystem the latter is blocked during the reaction with the imide halide-forming agent. The purpose of locking is to avoid that the carboxyl group is halolted by that agent, for instance. the phosphorpentaride. As blocking group, therefore, any compound be used, which converts the carboxyl group into a .p not reacting with that agent. If the desacyclated pound shall be isolated in the form of the free carzlic acid, a blocking group should be used which be split offwithout destruction of the bicyclic nus. Such blocking groups are, for instance, ester lps that can be split in an acidic or neutral or kly basic (up to pH 9) reaction medium, for ince by reduction, solvolysis, such as acid hydrolysis, )hotolysis. Advantageously, the carboxyl group is rified with compounds known in the field of noacids and peptides to be readily eliminable from ester grouping, especially in an non-alkaline men. Such compounds derive from elements of the &#39;th group (IV A) or the Periodic System having an nic weight of at most 120. For illustration may be red methanol substituted by at least one phenyl 1p, which latter may be substituted by one or more stituents selected from the group consisting of )geno, such as chloro, bromo, fluoro or iodo, lower l, lower alkoxy, especially methoxy, or nitro; exams of such alcohols are benzylalcohol, diphenylmenol, triphenylmethanol, para-methoxyphenylthanol, 3,5dimethoxybenzylalcohol, di-paralhoxyphenyl-methanol, para-nitrobenzylalcohol, 2,- -trimethyl-benzylalcohol, 3,4-dimethoxy-6-nitrolzylalcohol, a-phenyl-a-(3,4-dimethoxy-6- ophenyU-methanol, a-methyl-a-(3,4-dimethoxy-6&#39; -ophenyl)-methanol, furthermore methanol substiad by three lower alkyl groups, such as tert,-butanol, t.-amylalcohol or ethanol, substituted by 3 halogen ms in Z-position, e.g. trichloro-ethanol or tribrothanol; furthermore 2-iodoethanol, as well as tet- .ydropyranol or stannylalcohol. \s mentioned above, a carboxyl group substituting thiazacyclic ring has to be blocked only during the p of formation of the imide halide. After that step it 1 be split off, if desired. This splitting can be effected solvolysis, for instance with water or alcohols, if deed in an acidic or weakly alkaline medium, or by re- :tion, for instance by treatment with hydrogen in the :sence of a catalyst or with metals, such as zinc, as ll as by photolysis, preferably in a polar medium. I is also possible to retain a blocked group in the reting desacyl compound for further chemical reaction :h as conversion into another acyl derivative desired cause of its activity, and only thereafter to eliminate y blocking group. As is known, desacylated 3-aminolactam type compounds, for example 7-amino-ceph- )sporanic acid, have practically no pharmacological tivities, so that reacylation is necessary in any case. some cases, the elimination of the blocking group :er reacylation furnishes the active final product in tter yield. Reacylation can be effected with an aliatic, aromatic, heterocyclic, araliphatic or heterocyllaliphatic carboxylic acid radical, especially the acyl dical of 7-acylamino-cephalosporanic acids and 6- ylamino-penicillanic acids that are known to be antiatically effective, for example, a radical of the forula which n represents an integer ofO to 4, preferably 1, id in which a CH -group, especially in a-position may be substituted, for instance by amino, halogen, lower alkoxy, cyan, nitro or carboxyl, and R represents an unsubstituted or substituted aryl, cycloalkyl, or heterocyclyl radical or an aryloxy, arylthio, cycloalkoxy, heterocyclyloxy or heterocycly-lthio radical, the aryl or heterocyclyl radicals being monocyclic or dicyclic, for example, 2:6-dimethoxybenzoyl, tetrahydronaphthoxyl, 2-methoxynaphthoyl, Z-ethoxynaphthoxyl, 3- pyridyl-benzoyl, phenylacetyl, phenylglycyl, phenylalanyl, phenylcyanacetyl, p-chlorophenyl-cyanacetyl, phenoxyacetyl, S-phenyl-thioacetyl, S-bromophenylthioacetyl a-phenoxypropionyl, ,B-phenoxypropionyl, a-phenoxyphenylacetyl, a-methoxyphenylacetyl, a-methoxy- 3:4-dichlorophenyl-acetyl, pyridyl(3)- acetyl, pyridyl(2)-acetyl, l-methylimidazolyl(2)- thioacetyl, l,2,4-triazolyl(3 )-thioacetyl, thiozolinyl( 2 thioacetyl, imidazolinyl( 2 )-thioacetyl, l-methylimidazolyl(3)-acetyl, imidazolyl( l )-acetyl, benzyloxycarbonyl, S-benzylthioacetyl, S-benzylthiopropionyl, hexahydrobenzyloxycarbonyl, cyclopentanoyl, cyclohexanoyl, Z-thienylacetyl, Z-thienyl-cyanacetyl, 3- thienylacetyl, 2-furylacetyl, Z-indolylacetyl, Z-phenyl- 5methyl-isoxazolylcarbonyl, 2-(2&#39;-chlorophenyl)-5- methyl-isoxazolyl carbonyl, indenyl-carbonyl, or a radical of the formula in which n represents an integer of l to 7, and the chain is straight or branched and, if desired, is interrupted by an oxygen atom or a sulfur atom or is substituted, for instance, by halogen, cyan, carboxy, carbalkoxy, lower alkoxy, nitro or amino, for example, a propionyl, butyryl, hexanoyl, octanoyl, butylthioacetyl, acrylyl, a-cyano-Bdimethylacroyl, crotonyl, Z-pentenoyl, ally]- thioacetyl, chloracetyl. ,B-bromopropionyl, dichloroacetyl, dibromacetyl, difluoroacetyl, ethoxycarbonylacetyl, dimet-hoxycarbonylacetyl, cyanacetyl, a-cyanopropionyl, nitroacetyl, aminoacetyl, or a-carboxylpropionyl radical.  
  The starting materials may be primarily those of the formula COOR in which acyl is the acyl residue of a carboxylic acid, the group of the formula COOR represents a blocked carboxyl group, and S X is an S-methylene or an S-ethylidene grouping, in which grouping the carbon atom adjacent to the ring-carbon atom carrying the blocked carboxyl group is preferably substituted by methyl optionally carrying a group not taking part in the reaction.  
  A blocked ester grouping can also be retained, if it is split enzymatically in the tissue on administration of the compound.  
  The following scheme illustrates the splitting of the acylamino group from a specific Cephalosporin C starting material, the group of the formula COOR representing a blocked carboxyl group:  
 O\&#39; h I. A v&#34; S O h-Cr. (Cn )5-Cvmii ii. 1 I  
 0003 t -coc? iPCl pyridine 0003.4  
  &#39;cz K l coon o i B it v 1 iline. Usually the reaction is performed in an inertzsolvent, preferably methylene chloride. The molar proportion of the acylamino starting material: imide halide-forming reagent: base, such as a cephalosporine starting material: phosphorus pentachloride: pyridine, is preferably about 113112. The temperature should be about 20 to l0C.  
  According to the invention the imide halide is then reacted with an alcohol, usually in the presence of a base, particularly a tertiary amine such as one of those mentioned above to form an imino ether. Alcohols contain, for example, up to 18 carbon atoms and are, for example, aliphatic alkohols. such as lower alkanols. e.g. ethanol, n-propanol, isopropanol, n-butanol and especially methanol, cycloaliphatic alcohols, such as cycloalkanols, e.g. cyclohexanol. or araliphatic alcohols,  
 such as phenyllower alkanols, e.g. benzylalcohol.  
  In order to transform the imide halide, e.g. chloride as fast and as quantitatively as possible into the imino ether, a large excess of the alcohol, for example about 100 mols of methanol per mol of imide halide is used, and the reaction is carried out first at -20 to C and then for about one hour at room temperature. The imino ether is an intermediate which need not be isolated. but can be split in the same reaction medium.  
  The splitting of the C=N double bond of the imino ether to form the desired amino compound is carried out with a compound containing a hydroxyl group, preferably by hydrolysis, as well as by alcoholysis such as treatment with water, as well as with an alcohol, for instance one of those used for the formation of the imino ether, or with a mixture of alcohol with water, preferably in an acidic medium, e.g. at a pH value from 0 to 4, which may be attained by adding a buffer solution.  
  The hydrolysis of the imino ether to form the amino compound is preferably carried out in a mixture of an inert solvent, e.g. methylene chloride, and water, for instance with dilute aqueous hydrochloric acid in methylene chloride. Under these circumstances it is terminated within about 45 minutes at room temperature.  
  It is to be noted that the three steps of the overall reaction may all be carried out in the same solvent. e.g. methylene chloride, and in the same reaction vessel.  
 The following Examples illustrate the invention.  
 EXAMPLE 1 A solution of 674 mg (1 millimol) of crystalline phenylacetyl-cephalosporin C-dibenzyl ester in a mixture of 20 ml of methylene chloride and 674 mg (6 millimols) of pyridine is mixed with a solution of 308 mg (2 millimols) of phosphorus oxychloride in ml of methylene chloride; the whole is kept for 16 hours at 23C, then mixed with 2 ml of absolute ethanol and left to itself for a further 6 hours. The mixture is then evaporated under 0.1 mm Hg pressure and hydrolyzed in ml of dioxan with -10 ml of aqueous phosphoric acid of 5% strength for 19 hours at 20C. The batch is diluted with water, the dioxan expelled under vacuum, and the aqueous phase adjusted with solid tripotassium phosphate to pH 3.3 and extracted three times with chloroform+ether (1:3). The organic phases are washed with phosphate buffer (pH 3.3) and extracted three times with phosphoric acid of 3% strength. The chloroform+ether extract contains 540 mg of starting material (identified by thin-layer chromatogram on silica gel in systems 1 and 11; see Table 1). After the aqueous solution (pH 3.3) has been adjusted to pH 8.5, 19.9 mg of cephalosporin C-dibenzyl ester are extracted with ethyl acetate (identified in the thin-layer chromatogram in systems 1 and 11 by comparison with authentic material which is obtained from cephalosporin C by conversion into N-tertiary butyloxycarbonylcephalosporin C, esterification to form the dibenzyl ester and elimination of the tertiary butyloxycarbonyl group with trifluoracetic acid; see Table 1).  
  The phosphoric acid aqueous extract is adjusted with tripotassium phosphate to pH 8.5 and extracted with ethyl acetate. The organic phase is dried with sodium sulfate and evaporated to dryness. The residue (47 mg) is unitary in the thin-layer chromatogram in systems 1 and 11 and consists of 7-amino-cephalosporanic acid benzyl ester; see Table l. The infrared absorption spectrum in methylene chloride displays, inter alia. bands at 2.83 m .t (NH group), 5.62 mp. (B-lactam) and 5.77  
 mp. (ester) but, in contrast to the starting material, no bands appear at 2.98, 5.95 and 6.70 6.70 mu.  
  in order to identify the structure of 7-amino-cephalosporanic acid benzyl ester a crystalline derivative was prepared which was identified with authentic material:  
  400 mg (1.1 millimol) 7-amino-cephalosporanic acid benzyl ester are reacted in 10 ml of methylene chloride in the presence of 50 mg (0.6 millimol) of pyridine with 126 mg (1.2 millimols) of chlorethyl isocyanate for 17 hours at 22C. The batch is evaporated in vacuo, the residue taken up in chloroform+ether (1:3) and washed with aqueous phosphoric acid of 5% strength and aqueous dipotassium hydrogen phosphate solution of 10% strength. The neutral extract is dried over sodium sulfate, evaporated in vacuo and recrystallized from acetone+ether to yield 461 mg 90% of the theoretical yield) of 7-(B-chloroethylureido)cephalosporanic acid benzyl ester in the form of colorless needles; melting point: ll77C; optical rotation [0:1 1 1 i 1 (0 1, chloroform), ultraviol absorption spectrum: A 264 ma (6 8100). The product is identical with material synthetized from 7-amino-cephalosporanic acid.  
 Table l The iodine-starch reagent was prepared as described by R. Thomas in Nature 191, page 1161 (1961 By hydrogenation in glacial acetic acid in the presence of palladium carbon of 10% strength. 7-amino-cephalosporanic acid benzyl ester is transformed into 7-amino-cephalosporanic acid.  
  The phenylacetyl cephalosporin C-dibenzyl ester used as starting material may be prepared as follows:  
  534 mg (l millimol) of N-phenylacetylcephalosporin C in 50 ml of dioxan are esterified with 2.5 millimols of phenyldiazomethane in 15 ml of ether for 1 hour at 22C. The batch is evaporated in vacuo, taken up in chloroform+ether (1:3) and washed with aqueous phosphoric acid of 10% strength, aqueous dipotassium hydrogenphosphate solution of 10% strength and saturated sodium chloride solution. The evaporated organic phase is triturated with ether and yields 539 mg of N-phenylacetyl cephalosporin C-dibenzyl ester which is sparingly soluble in ether and which is crystallized from acetone; m.p. 156 157C.  
 , EXAMPLE 2 i 200 mg (0.3 mmol) of crystalline N-p henyla cetylcephalosporin C-dibenzyl ester in 13 ml of methylene chloride are allowed to react at 22C for 4 days with ranic acid esters. The latter have the following R, values in the paper chromatogram. system I (nbutanol-Facetic acid 10:1, saturated with water): methyl ester: Rf I 0.13; ethyl ester: R, I 0.15; nbutyl ester: R l 0.16; yellowish brown coloration with ninhydrin-l-collidine or bioautographic identifi-. cation with Staph. aureus after sprinkling with l-molar pyridine in acetone+water 1:1) and 1% phenyl-acetyl chloride in acetone. The ultraviolet spectrum shows a maximum at 263 mp. (e 8000).  
  The diesters used as starting material are prepared by reacting N-phenylacetyl-cephalosporin dissolved in methanol with a 5% ethereal solution of diazomethan&#39;e, diazoethane or diazobutane. The R, values of N-phenylacetyl-cephalosporin C-diesters in the paper chromatogram in the system I (n-butanol+acetic acid :1 saturated with water) and system 111 (n-butanol, saturated with water +1% glacial acetic acid) respectively are: dimethyl ester: R lll =0.76; diethyl ester: R, 1 0.85; dibutyl ester: R; 111 0:87 (bioautographic identification with Staph. aureus).  
 EXAMPLE 3 406 mg (0.59 mmol) of crystalline N-carbobenzoxycephalosporin C-dibenzyl ester in ml of methylene chloride are mixed with3 16 mg (4.0 mmol) of pyridine and 200 mg (1.3 mmol) of phosphorus oxychloride and the mixture allowed to stand at C for 88-hours with exclusion of moisture and light. The mixture is then treated with 2 ml of absolute alcohol, left to itself for another 8 hours, treated with 1 ml of pyridine, and evaporated under reduced pressure. For hydrolysis, the residue is taken up in 20 ml of dioxan and 10 ml of 2% aqueous phosphoric acid. and allowed to stand at 22C for 15 hours. Working up as described in Example 1 yields 65 mg (0.179 mmol) of pure 7-amino-cephalosporanic acid-benzyl ester. f  
  The N-carbobenzoxy-cephalosporin C-dibenzyl ester used as starting material is-prepared as follows:  
  4.73 g l0 millimols) of cephalosporin C-so dium salt are dissolved in 200 ml of aqueous sodium bicarbonate solution of 10% strength and slowly treated with 150ml of acetone and at 0C with a solution of 2.30 g (13.5  
 millimols) ofchloroformic acid benzyl ester in 50 ml of acetone. The batch is stirred for 30 minutes at 0C, for 1 hour at 22C. and the acetone is then evaporated in vacuo. The aqueous phase is first washed with ethyl ac etate. then at a pH value of 2.0estracted with ethyl ac-&#39; etate while being salted out (sodium chlori.de)..The &#39;extract is dried over sodium sulfate and evaporated to 10 yield 4.437 g of N-carbobenzoxy-cephalosporin C. Thin layer chromatogram on silica gel in system I: R 0.30.  
  14.42 &#34;&#34;g 8.05 millimols) of N-carbobenzoxycephalosporin C are dissolved in ml of dioxan, treated with 1110 m1 ofa solution of 19.8 millimols of phenyldiazomethane in dioxan and allowed to react for 1 hours at 22C. The batch is then evaporated to dryness in vacuo and the residue triturated with petroleum ether+ether (1:1). The insoluble portion is taken up in chloroform+ether (1:3) and washed with 2N-sodium bicarbonate. The organic phase is dried over sodium sulfate, evaporated (4.96 g) and crystallized from acetone+ether to yield crystalline N carbobenzoxy cephalosporin C-dibenzyl ester melting at l 33135C.  
 EXAMPLE 4 216 -mg (0.296 mmol) of crystalline N-2,4- dinitrophenyl-cephalosporin C-dibenzyl ester in 1 1 ml of methylene chloride are mixed with 158 mg (2.0 mmol) of pyridine and 100 mg (0.65 mmol) of phosphorus oxychloride and the mixture kept at 23C for 8 days with exclusion of moisture and light. After the addition of 2 ml of absolute alcohol, and mixture is allowed to stand for another 8 hours, then treated with 1 ml of pyridine, and evaporated to dryness under reduced pressure. The residue is hydrolyzed for 16 hours at 22C with a mixture of 20 ml of dioxan and 10 ml of 3% aqueous phosphoric acid. Working up in a manner analogous to that described in Example 1 yields 62 mg (0.171 mmol 58% of theory) of pure 7-amino-cephalosporanic acid-benzyl ester.  
  The N-2:4-dinitrophenyl-cephalosporin C-dibenzyl ester used as starting material may be prepared as follows:  
  11.63 g of N-2:4-dinitrophenyl-cephalosporin C are dissolved in ml of dioxan and treated with 250ml of a phenyldiazomethane solution of 2% strength for 25 minutes at 22C with&#39;stirring. When the addition is complete, the batch is allowed to stand for 20 minutes and then concentrated extensively in vacuo. The residue is taken up in chloroform and then washed 3 times each withZN-hydrochloric acid, N-sodium bicarbonate and water. The organic phase is dried and evaporated to yield 15.54 g of crude product. The latter is triturated with ether to remove the portions soluble in ether (2.42 g). The portions which are insoluble in ether 12.84 g) are crystallized from acetone+ether to yield 9.98 g of crystalline N-2:4-dinitrophenyl-cephalosporin C-dibenzyl ester which on recrystallization melts at 109 111C; optical rotation [M +31.5 i1 c 1 in chloroform).  
  In an analogous manner the dimethyl, diethyl and din-butyl ester of N-2:4-dinitro-phenyl-cephalosporin C are converted into the7-amino-cephalosporanic acid methyl ester, the 7-amino-cephalosporanic acid ethyl ester and the 7-amino -cephalosporanic acid n-butyl ester respectively.  
  The diesters used as starting materials may be prepared by reacting a methanolic solution of N-2z4- dinitrophenyl-cephalosporinC with a 5% ethereal solution of diazomethane, diazoethane or diazobutane.  
  The R; values of the N-2z4-dinitrophenylcephalosporin C-diesters in the paper chromatogram in systems land III are:&#39; dirnethyl esterrR l 0.73; R} 111 0.76; diethyl ester: R, l&#39; 0.78 dibutyl ester: R, I 0.82; R&#39; &#34;1Il =-&#34;0.85. Melting point: 103-104C.  
  11 EXAMPLE 216 mg (0.296 millimol) of crystalline N-2z4- dinitrophenyl-cephalosporin C-dibenzyl ester in 1 1 ml of methylene chloride are allowed to stand in the dark with 158mg (2.0 millimols) of pyridine and 100 mg (0.65 millimol) of phosphrous oxychloride for 8 days at C with the exclusion of moisture. 2 ml of absolute alcohol are added, and the bath is allowed to stand for another 8 hours. after which a mixture of 26 ml of dioxan and 13 ml of aqueous phosphoric acid of 5% strength are added. The solution is freed from methylene chloride in vacuo until there is only one phase and then allowed to stand for 16 hours at 22C for hydrolysis. The batch is diluted with water, freed from organic solvent in vacuo. adjusted to a pH value of 3.3 and extracted with a mixture of benzene and ethyl acetate (2:1). The organic phase is extracted with aqueous phosphorus acid of 3% strength and the phosphoric acid solution is adjusted to a pH value of 8.5 and extracted with ethyl acetate. The ethyl acetate extract is dried over sodium sulfate and evaporated to yield 53 mg 49% of the theoretical yield) of pure 7-amino-cephalosporanic acid benzyl ester.  
 EXAMPLE 6 1f 2 ml of methanol are used instead of 2 ml of ethanol, the remaining conditions and procedure being the same as those described in Example 5, 59 mg 55% of the theoretical yield) of 7-amino-cephalosporanic acid benzyl ester are obtained.  
 EXAMPLE 7 203 mg (0.296 millimol) of N-phthaloylcephalosporin C-dibenzyl ester are allowed to react in methylene chloride with pyridine and phosphorus oxychloride, as described in Example 5, and hydrolysed and worked up as described in that Example. 48 mg 45% of the theoretical yield) of pure 7-amino-cephalosporanic acid benzyl ester are obtained.  
  The N-phthaloyl-cephalosporin C -dibenzyl ester may be prepared as follows:  
  473 mg 1 millimol) of cephalosporin C are taken up in 10 ml of an aqueous dipotassium hydrogen phosphate solution of 10% strength and the pH value of the mixture is adjusted to 9 with tripotassium phosphate. 4 ml of acetone are added and then. with stirring, 6 ml of acetone containing 285 mg 1.3 &#39;millimols) of N-carbethoxy-phthalimide, and the batch is stirred for 1 hour at 22C. the pH value being kept constant by the addition of further tripotassium phosphate. The batch is then diluted with water. the pH value is adjusted to 7 with phosphoric acid. the acetone is removed in vacuo and the aqueous solution washed three times with ethyl acetate. The aqueous phase is then adjusted to pH 2 with phosphoric acid and the product extracted with ethyl acetate. The extract is dried over sodium sulfate and evaporated to yield 505 mg 93% of the theoretical yield) of N-phthaloyl-cephalosporin C.  
  According to the thin-layer chromatogram on silica gel in system I the product is unitary; R 0.21 (colorless spot on a violet background after sprinkling with iodine starch reagent; method: R. Thomas. Nature 191. 1161119611).  
  5 g (9.16 millimols) of N-phthaloyl-cephalosporin C are dissolved in 100 ml of dioxan and treated with stirring with 160 ml of an ethereal solution of 22 millimols of phenyldiazomethane and allowed to react for half an hour. After the addition of 2 ml of glacial acetic acid,  
 the batch is evaporated in vacuo. taken up in chloroform+ether (1:3) and washed in succession with aqueous phosphoric acid of 5% strength, aqueous dipotassium&#39;phosphate solution of 10% strength and saturated, aqueous sodium chloride solution. The organic phase is dried over magnesium sulfate to yield 8.52 g of evaporation residue which is digested first with petroleum ether then with ether. The residue (5.06 g) which is insoluble in both solvents is N-phthaloyl-cephalosporin C-dibenzyl ester. The product is unitary according to the thin-layer chromatogram on silica gel (system 11: R, =0.74) and absorbs in the ultraviolet absorption spectrum at 264 mp. (e 8200).  
 EXAMPLE 8 660 mg (l millimol) of N-benzoyl-cephalosporin C- dibenzyl ester in 40 ml of methylene chloride are allowed to stand with 593 mg (7.5 millimols) of pyridine and 368 mg (2.4 millimols) of phosphorus oxychloride for 7 days at 25C with the exclusion of light and moisture. 7 ml of absolute ethanol are then added, the reaction mixture is allowed to stand for another 8 hours. 3 ml of pyridine are added and the whole evaporated in vacuo. For the purpose of hydrolysis the residue is taken up in ml of dioxan and 35 ml of aqueous phos-.  
 phoric acid of 3% strength and allowed to stand for 15 hours at 22C. The bath is worked up as described in Example 1 and yields 1 14 mg 32% of the theoretical yield) of pure 2-amino-cephalosporanic acid benzyl ester.  
  The N-benzoyl-cephalosporin C-dibenzyl ester used as starting material may be prepared as follows:  
  A solution of 5 g (10.5 millimols) of cephalosporin C-sodium salt in 150 ml of aqueous dipotassium hydrogen phosphate solution of 10% strength is treated with ml of acetone and at 0 5C slowly with a solution of 2.1 g 15 millimols) of benzoyl chloride in 21 m1 of acetone. The batch is allowed to stand for half an hour at 0 5C and for half an hour at 22C (water-bath) and the acetone is then removed in vacuo. The aqueous phase is washed with ethyl acetate, washed at a pH value of 3.3 with benzene and finally extracted at a pH value of 2.0 with ethyl acetate. The extract is dried over sodium sulfate and evaporated to yield 4.24 g 78% of the theoretical yield) of N-benzoyl-cephalosporin C which crystallizes from ethyl acetate in the form of needles melting at 113 1 17C.  
  For the purpose of esterification 3.5 g (6.7 millimols) of N-be nzoyl-cephalosporin C are dissolved in ml of dioxan and allowed to react for 45 minutes with a solution of 13.5 millimols of phenyldiazomethane in 90 ml of ether. The reaction mixture is evaporated, taken up in a mixture of chloroform and ether (1:3) and washed in succession with aqueous phosphoric acid of 10% strength. aqueous dipotassium hydrogen phosphate solution of 10% strength and saturated sodium chloride solution. The organic phase is dried and evaporated and the residue triturated with ether to yield 4.35 g of N-benzoyl-cephalosporin C-dibenzyl ester which crystallizes from acetone and melts at 178 EXAMPLE 9 746 mg (1 millimol) of N-phthaloyl-cephalosporin C-di-(para-methoxy-benzyl ester) in 40 ml of methylene, chloride are reacted with 538 mg (6.8 millimols) of pyridine and 338 mg (2.2 millimols) of phosphorus oxychloride at 22C for 8 days. The batch is allowed to ganic stand for 8 hours at 22C with 6 ml of alcohol and then treated with 120 ml of a mixture of dioxan and wat er (2:1) for the purpose of hydrolysis. The hydrolysis is carried out as described in Example 5 and the reaction mixture worked up with a mixture of benzene and ethyl acetate (5:2) to yield 184 mg (=48% of the theoretical yield) of 7-amino-cephalosporanic acid para-methoxybenzyl ester. Thin-layer chromatogram on silica gel in system 11: R 0.50; &#39;in system l: R 0.72. The ester is split off to form 7-amino-cephalosporanic acid by subjecting the product to 5 minutes reaction with anhydrous trifluoracetic acid.  
  The N-phthaloyl-cephalosporin C-di-(paramethoxybenzyl ester) used as starting material may be prepared as follows:  
  2.73 g (5 millimols) of .N-phthaloyl-cephalosporin C and 1.66 g (.12 millimols) of anisyl alcohol are dissolved in &#39;30 ml of dioxan. After cooling to C, a solution of 2.88 g 14 millimols) of dicyclohexyl carbodiimide in ml of dioxan is added in one portion, the mixture is allowed to stand for minutes at 10C and for 1 hour at room temperature. The dicyclohexylurea formed is filtered off, the filtrate lyophilized, the residue taken up in a mixture of benzene and ethyl acetate (5:2), washed four times with aqueous secondary potassium phosphate solution of 10%- strength and twice with a sodium chloride solution. The extract is dried over sodium sulfate and evaporated to yield 3.44 g (92.4%) of N-phthaloyl-cephalosporin C-di-(paramethoxy-benzyl ester). The product is taken up in a mixture of benzene and petroleum&#39;ether (6:4) and purified on silica gel (Merck). The substance can be eluted with benzene-l-chloroform (2:8).  
  According to the thin-layer chromatogram on silica gel in n-butyl acetate as eluant the product is unitary: R 0.55 (colorless spot on a violet background after sprinkling with iodine starch reagent; cf. R. Thomas, Nature 191, 1161 119611).  
  The substance crystallizes in the form of clusters from methylene chloride+petroleum ether: m.p. 124 127C. Ultraviolet absorption spectrum in rectified spirit: A 258 mu (6 8700).  
 &#39; EXAMPLE 10 2.63 g (3 millimols) of crystalline N-phthaloylcephalosporin C-dibenzhydryl ester are allowed to react in m1 of methylene chloride for 10 days at 20C with 1.58 g (20 millimols) pyridine and 1.00 g  
 (6.5 millimols) of phosphorus oxychloride. 20 ml of methanol are added to the reaction mixture which is then allowed to stand for another 8 /2 hours. 260 ml of dioxan and 130 ml of aqueous phosphoric acid of 5% strength are then added. shaken for a short time&#39;and then concentrated in vacuo until the mixture is homogeneous. The batch is allowed to stand for 15 hours at 22C, diluted with 50 ml of water. and the dioxan evaporated in vacuo. The aqueous phase g) is treated with 70 ml of alcohol and extracted three times with a mixture of benzene and ethyl acetate (5:2). The orphases are washed four- &#39;times with 2N- hydrochloric acid+alcohol (2:1 The combined aque- 5.76 and 5.78 a (shoulder only). In the thin-layer chromatogram on silica gel in system 1 the R,= 0.58 and in the system benzene+acetone (7:3): R, 0.51. The N phthaloyl-cephalosporin C-dibenzhydryl ester used as startingmaterial may be prepared as follows:  
  a. 1.09 g (2 millimols) of N-phthaloyl-cephalosporin C (purityabout 78%) are dissolved in 16.5 ml ofdioxan and treated with 776 mg (4.milli &#39;rnols) ofdiphenyldiazomethane in 12 ml of dioxana The deep purpleviolet reaction solution is allowed to stand for 5 hours in the dark at 22C. The solution which is now only pale pink is evaporated in vacuo, the residue taken up in 200 ml of chloroform, washed twice with ice-cold N- sodium bicarbonate and finally with sodium chloride solution of 10% strength The chloroform extract dried with sodium sulfate is evaporated in vacuo and the residue (1.66 g) triturated three times with 20 ml of ether. The digestion residue (1.23 g) is recrystallized from acetone+di-n-propyl ether to yield 1.12 g of N-phthalyl-cephalosporin C-dibenzhydryl ester melting at 158.5 160C. Infrared absorption spectrum in Nujol: bands inter alia at 3.05 ,u., 5.62 u,5.71 u, 5.80 t, 6.00 ,u, 6.07 [.L (shoulder), 6.44 t, 6.85 p. (broad), 7.26 ,u, 7.66 p, 7.90 p. and 8.21 ;.t.  
  Ultraviolet absorption spectrum in ethanol: A, max 259 mu (6 9100), A max 264 mp. (e 9100).  
  R, values in the thin-layer chromatogram on silica gel: system benzene+acetone (8:2): 0.49; system cyclohexane+ethyl acetate (1:1):0.28.  
  Reaction according to Reindel and Hoppe greyviolet. Reaction with iodine starch-acetic acid (according to R. Thomas, (loc.cit.): weakly positive.  
  b. 10 g (18.3 millimols) of N-phthaloylcephalosporin C are dissolved in ml of a mixture of dioxan and methanol (9:1) and treated at 20C with stirring for half an hour with a clear-filtered solution of 8.5 g (43.8 millimols) of diphenyldiazomethane in 50 ml of petroleum ether. 20 ml of methanol are then added and the batch is stirred for another hour, evaporated in vacuo, crystallized from ethyl acetate and the crystals washed with ether. The yield of crystalline N- phthaloyl cephalosporin C-dibenzhydryl ester is 84% of the theoretical yield; colorless needles; mp -16lC.  
 EXAMPLE 1 1 The 7-amino-cephalosporanic acid benzhydryl ester obtained as described in Example 10 may be hydrolysed as follows:  
  438 mg (1 millimol) of 7-amino-cephalosporanic acid benzhydryl ester are dissolved in-5qml of anisole. treated with 20 ml of anhydrous trifluoracetic acid and after 5 minutes rapidly evaporated under 0.1 mm pressure of mercury. The residue taken up in ethyl acetate is extracted&#39;with aqueous trifluoroacetic acid of 1% strength. The aqueous phase is adjusted to a pH value -of 3.5 with pyridine, then highly concentrated in vacuo layer chromatogram on silica gel in the system:&#39;n-  
  butanol+ ous phases are neutralized to a pH value of 6, freed from alcohol in vacuo.; and extracted at pH 8.0 with ethyl acetate, dried over sodium sulfate and then evaporated. 871 mg 66% of the theoretical yield) of&#39; pyridine+glacial acetic acid+water (30:20:6q24); R 0.45; brown coloration with ninhydrincollidine) the product is unitary and identical with 7-amino-cephalosporanic.acid benzhydryl esterare obtained. The infrared absorption spectrum (methylene chloride) displays in the carbonyl zone bands at I authentic material. The microbiological plate test I (Staphylococcus aureus) shows the same inhibition zones after p henylacetylation. For further characterization the 7-amino-cephalos poranic ac&#39;id benzhydryl ester is converted into the 7- ester in a manner analogous to that described in Example 1. According to the thin-layer chromatogramon silica gel in thesystem benzene+acetone (8:2) R =0.32,-  
 the product is unitary and identical with the product which isprepared from authentic 7-amino-cephalosporanic acid by reaction with chlorethyl isocyanate and subsequent esterification with diphenyldiazomethane. This ester too may be hydrolyzed easily to the free. car-, boxylic acid with trifluoracetic acid as described above.  
 EXAMPLE 12 of methylene chloride, treated with 2.4 ml (30 millimols) of pyridine and, with cooling, with 12.5 ml of a 10% solution of phosphorus pentachloride (6 millimols) in methylene chloride. The reaction mixture is allowed to stand for 20 minutes at 20C, 20 ml of methanol are added with cooling, and the batch allowed to stand for another 6 hours. The mixture is then poured on to well stirred 450 ml of dioxan-l aqueous phosphoric acid of 5% strength (2:1 the methylene chlo ride is removed in vacuo until the solution is homogeneous, and the batch hydrolyzed for 15 hours at 22C. The batch is worked up as described in Example 10 but with 2N-hydrochloric acid-l-alcohol (1:1) instead of (2: 1) to yield 1.1 14 g of crude product from which by trituration with ether 710 mg 54% of the theoretical yield) of pure 7-amino-cephalosporanic acid benzyhyd- EXAMPLE 13 26.3 g (0.03 mol) of crystalline N-phthaloylcephalosporin C-dibenzyhydryl ester are dissolved in 1 liter of absolute methylene chloride, treated with 29.0 ml (0.36 mol) of pyridine and, with cooling, with 187 ml of a solutionof phosphorus pentachloride (0.09 mol) in methylene chloride. The reaction mixture is allowed to stand for half and hour in a water bath at C, 200 ml of methanol are added with cooling and the batch allowed to stand for another 6 hours. The reaction solution is then poured on to a well stirred mixture of 1.3 liters of dioxan and 0.5 liter of aqueous phosphoric acid of 7% strength, the methylene chloride is removed in vacuo until the solution is homogeneous,  
 are simultaneously poured into 100 ml of stirred aqueous dipotassium hydrogen phosphate solution of 3% strength (final pH value 6.5 The two phases are separated and the lower one extracted with 2 portions of ethyl acetate. The ethyl acetate extracts are &#39;washed twice with aqueous dipotassium hydrogen phosphate solution of 3% strength, the combined aqueous phases are adjusted to apH value of 3.5 with concentrated hydrochloric acid and the solution, concentrated to abut 100 ml. is crystallized at 0C to yield 6.14 g 75% of the theoretical yield) of pure 7-amino-cephalosporanic acid. Ultraviolet absorption spectrum (in 0.1N-sodium bicarbonate solution): 263 my. (e 8300). [01],, 118 (C 1 in 0.5 N-sodium bicarbonate).  
 EXAMPLE 14 In an&#39;analogous manner to that described in Example 13 N-phthaloyl-cephalosporin C-di-tetrahydropyram 2-yl ester can be converted into 7-amino-cephalosporanic acid tetrahydropyran-Z-yl ester. 1n the thin-layer chromatogram in system 11 the R,= 0.41  
 The starting material may be prepared as follows:  
  2.73 g of N-phthaloyl-cephalosporin C are covered with 10 ml of 2:3-dihydro-4-pyrane, cooled with a mixture of ice and sodium chloride to l0C and treated with stirring with mg &#39;of para-toluenesulfonic acid and after 20 minutes with a further 50 mg of para-toluenesulfonic acid. Stirring is continued for 3 hours in a cold bath with the exclusin of mooisture, the batch is diluted with 20 ml of dioxan and poured in a thin jet into an ice-cold, vigorously stirred phosphate buffer of about 10% strength having a pH value of 9.5. The aqueous phase freed from the organic solvent in vacuo is extracted with a mixture of benzene and ethyl acetate (5:2). The extract is rendererd alkaline by the addition of5 ml of pyridine, dried over sodium sulfate and evap-&#39; orated in vacuo to yield a neutral crude product which is freed from contaminants by being digested with mixtures of petroleum ether and ether (first 98:2 and then 3: 1) containing pyridine of 1% strength in which mixtures the contaminants are soluble. 2.36 g of N-phthaloyl-cephaosporin C-di-tetrahydropyranyl ester are obtained. In the thin-layer chromatogram on silica gel in the system benzene+acetone (7:3) the compound shows an R, value of 0.40. The infrared absorption spectrum in methylene chloride displays, inter alia, bands at 5.64, 5.75, 5.82, 5.91, 7.27, 7.41, 8.35. 8.49, 8.86, 8.98, 9.08, 9.41, 9.48, 9.70, 10.65 and 1 1.60 mp.  
 EXAMPLE 15 When N-2:4-dinitrophenyl-cephalosporin C-diparanitrophenyl ester is used as starting material in the process of Example 13, 7-amino-cephalosporanic acid paranitrophenyl ester is obtained. R, value in the paper chromatogram, system I 0.26; yellow-brown coloration with ninhydrin-collidine or bioautographic identification with Staphylococcus aureus after sprinkling with l-molar pyridine in acetone+water 1:1 and a 1% solution of phenylacetyl chloride in acetone. 1n the ultraviolet spectrum maximum at 263 mp. (e 7900).  
 The starting material may be prepared as follows:  
  15 g of N-2z4-dinitrophenyl-cephalosporin C are dissolved in 600 ml of absolute pyridine, treated with 8 g of para-nitrophenol and 20 g of N:N-dicyclohexy1carbodimide and allowed to stand for 14 hours at 22C. The dicyclohexylurea which has crystallized out is filtered off and evaporated in vacuo. The solution of the residue in 1 liter of ethyl acetate is washed with 2N- hydrochloric acid, water and saturated sodium chloride solution, dried over sodium sulfate, evaporated in .amorphous N-2:4-dinitrophenyl-cephalosporin C-dipara-nitrophenyl ester. R, value in the thin-layer chromatogram on silica gel. system: chloroform+methan0l (95:5 0.70. The infrared spectrum in Nujol displays,  
 inter alia. bands at 5.63. 5.70. 5.85. 6.00. 6.16. 6.27. 6.546 and 7.44 [.L.  
 EXAMPLE l6 ln an analogous manner to that described in Example 13 N-phenylacetyl-cephalosporin C-monomethyl ester desacetyl lactone is treated to yield 7-amino-cephalosporanic acid desacetyl lactone already described.  
 The starting material may be prepared as follows:  
  1 g of N-phenylacetyl-cephalosporin C is dissolved in 20 ml of dioxan. treated with stirring with excess ethereal diazomethane solution and then allowed to stand for 30 minutes at 22C. 0.5 ml of glacial acetic acid is added to the reaction mixture and evaportion is carried out in vacuo. A chloroform solution of the evaporation residue is wshed neutral with N-hydrochloric acid. N- sodium bicarbonate and water. dried over sodium sulfate and evaported to yield 972 mg of N-phenylacetylcephalosporin C-dimethyl ester.  
  506 mg of N-phenylacetyl-cephalosporin C-dimethyl ester are dissolved in 50 ml of a mixture of methanol and dioxan (3:1 treated with 1 ml of concentrated hydrochloric acid and allowed to stand for 2 /2 days at 2C. The reaction mixture is then diluted with 60 ml of water and concentrated to about 40 ml in vacuo. The chloroform extract of the acidic aqueous phase is washed with N-sodium bicarbonate solution and water. dried over sodium sulfate and evaporated. 468 mg of evaporation residue are obtained which are chromatographed on 50 g of silica gel. The fractions eluted with a mixture of chloroform and methanol (9812) contain N-phenylacetyl-cephalosporin C-monomethyl ester descetyl lactone.  
  The infrared spectrum in Nujol displays a lactone band at 5.62 p.. Further bands are. inter alia. at 3.03. 3.37. 3.45. 5.57. 5.70. 5.93. 6.ll. 6.36. 6.50. 6.85. 7.24. 7.57. 7.76. 7.95. 8.28. 8.47. 8.74. 8.93. 9.10. 9.23. 9.79. l0.l l. 1363 1; (the bands at 3.37. 3.45. 6.85. 7.24 and 13.63;; belong to Nujol). The compound is unitary according to the paper chromatogram (system: nbutanol-l-methanol-l-water 2: 1 :2: R;= 0.88).  
 EXAMPLE 17 162 mg (0.296 millimol) of 7-[4-( l-phenyl-2-thiono- 5-oxo-imidazolidine-4-yl)-butyryl]-amino-cephalospo ranic acid methyl ester are allowed to stand for 6 days at 22C in l l ml of methylene chloride together with 237 mg 3.0 millimols) of pyridine and l54 mg (l millimol) of phosphorus oxychloride. After the addition of 2 ml of absolute alcohol the batch is allowed to stand for another 8 hours. is treated with 1 ml of pyridine and evaporated in vacuo. The residue is hydrolyzed for hours at C with a mixture of 20 ml of dioxan and 10 ml of aqueous phosphoric acid of 39% strength. Working up in the manner decribed in Example 1 yields 7-amno-cephalosporanic acid methyl ester.  
  In an analogous manner the ethyl and n-butyl ester of 7-[4-( l-phenyl-2-thiono-5-oxo-imidaZolidine-4-yl)- butyrylI-amino-cephalosporanic acid is converted into 7-amino-cephalosporanic acid ethyl ester and 7-amino-cephalosporanic acid n-butyl ester respectively.  
  The esters used as starting materials may be prepared as follows:  
  A solution of 15 grams of cephalosporin C in 150 ml of water and 150 ml of pyridine (at pH 7.5) is heated to 37C and mixed with l 1.9 ml of N-sodium hydroxide solution (at pH 9.0). 7.5 ml of phenyl isothiocyanate are then added. while keeping the temperature (37C) and the pH value (9) constant by dropping in N-sodium hydroxide solution. of which 60% of the calculated amount are consumed within the first 10 minutes. After minutes. 71% of the theoretical amount of sodium hydroxide solution has been consumed. The mixture is diluted with 400 ml of water and agitated 3 times with 1 liter of benzene on each occasion and once with 500 ml of ether. The aqueous phase is then adjusted to pH 1.7 with concentrated hydrochloric acid. the precipitate being dissolved by adding 600 ml of dioxan. and the whole is left to itself for 2 /2 hours at 22C. The solution is slightly concentrated under vacuum and then again diluted with water and exhaustively extracted with ethyl acetate. The extracts are washed with saturated sodium chloride solution. dried over sodium sulfate and evaporated to yield 17.07 grams of residue. The colorless. amorphous 7-[4(l-phenyl-2-thiono-5- oxo-imidazolidine-4-yl) butyryl]-amino-cephalosporanic acid is revealed by its paperchromatogram (after bioautographic development with Staphylococcus aureus) to be unitary and has in the system n-butanol:methanol:water (2: l :2) an R value ofO.68, and in the system n-butanol (saturated with water) glacial acetic acid (98:2) an R value of 0.41. Inhibition zones of 1% solutions in acetone on paper roundels of 6 mm diameter: Staphylococcus aureus 24 mm; Bacillus subtilis 30 mm; Staphylococcus aureus. resistant to penicillin. 21 mm. The esters are obtained by alkylation of this acid with diazomethane, diazoethane or diazobutane. respectively, in an analogous manner to that described in Example 2.  
 EXAMPLE 18 29 ml of absolute pyridine are added to a solution of 26.3 g of crystalline N-phthalyl-cephalosporin C-dibenzhydryl ester in 1 liter of absolute methylenechloride. and the whole is cooled to -l0C. ln the course of 2 minutes 187 ml of a 10% phosphorus pentachloride solution in absolute methylenechloride are then stirred in and the batch is stirred on for half and hour while maintaining the temperature all the time at l0C. 200 ml of ice-cold absolute methanol are then rapidly (within /2 minute) added to the solution and the temperature is maintained for another 30 minutes at -l0C. The batch is then heted on a water bath at +20C and stirred for 1 hour at this temperature. The solution is then rapidly (within /2 minute) mixed while being stirred with /2 liter of an ice-cold aqueous solution of 35 ml of orthophosphoric acid and the mixture is stirred for 1 /2 hours at 20C. adjusted to pH 8 with bout 530 ml of 50% aqueous tri-potassium phos phate solution. and the bottom methylene chloride phase is separated. The aqueous upper phase is further extracted with liter of methylenechloride. The combined methylene extracts are dried over sodium sulfate and evaporated under vacuum, to yield 34 to 40g (depending on the degree of drying) of a liquid residue which is further dried for about 30 minutes at room temperature under 0.1mm Hg pressure. This residue contains the 7-amino-cephalosporanic acid benzyhydryl ester which is taken up in 15ml of anisole and mixed with 45ml of trifluoroacetic acid while being cooled. The dissolution of the residue is accelerated by vigorous swirling ofthe vessel which is then kept for 15 minutes at about 20C. The solution is then rapidly poured into 700ml of stirred. cold methanol. and at the same time the pH (pH meter) of the methanolic solution is adjusted to 3.5 by adding about m] of tri-nbutylamine. Subsequently, the Ph value is adjusted finely by diluting 0.5ml-specimens with 4.5m] of water each and then meauring these dilutions with the pH meter. The solution is cooled for 2 to 15 hours to to +C and then filtered. The residue is washed successively with methanol, methylenechloride and ether and then dried under vacuum, to yield 6.68g 81% of the theoretical yield) of 7-amino-cepha1osporanic acid. Ultraviolet absorption spectrum (in 0.1N-sodium bicarbonate solution: A 263mp. (e 8000). Optical rotation [01],, +118 (c 1, in 0.5N-sodium bicarbonate solution).  
 EXAMPLE l9 23ml of absolute pyridine are added to a solution of 263g of crystalline N-phthalyl-cephalosporin C-dibenzhydryl ester in 263ml of absolute methylenechloride, and the whole is cooled to -10C. In the course of 2 minutes 150ml of a 10% solution of phosphorus pentachloride in absolute methylenechloride are then stirred in and stirring is continued for /2 hour while maintaining all the time a temperature of lOC. 1n the course of /2 minute the solution is rapidly mixed with 100ml of ice-cold absolute methanol and the temperature is maintained at 10C for another minutes. The batch is heated in a water bath to +20C and stirred at this temperature for 1 hour. While stirring the solution it is then rapidly (within /2 minute) mixed with 250ml of ice-cold aqueous N-hydrochloric acid and stirred for 4 hour at 20C.  
 50ml of 50% aqueous tri-potassium phosphate solution are then added at the pH value is adjusted to 8.0.  
 with about 230ml of ZN-aqueous sodium hydroxide solution. From the mixture (which tends to emulsification) the methylenechloride layer is separated by centrifugation, and the aqueous phase is further extracted with 200ml of methylenechloride. The methylenechloride extracts are combined, dried over sodum sulfate and evaporated under vacuum. to yield 34 to 38g (depending on the degree of drying) of a liquid residue which is further dried for about /2 hour under 0.1mm Hg pressure at room temperature. The residue contains the 7-amino-cephalosporanic acid as described in Example 18. This acid has the same degree of purity as the product of Example 18.  
 EXAMPLE 20 1.15kg of absolute pyridine are added to a solution of 1kg of crystalline Nphthalyl-cephalosporin C-dibenzhydryl ester in 30 liters of absolute methylenechloride. and the whole is cooled to 16C. Within 10 minutes a solution of 730g of phosphorus pentachloride in 13 liters of absolute methylenechloride is then stirred in. during which the temperature rises to 31C. The batch is stirred for minutes at 12C and then mixed within 3 minutes with 7.5 liters of absolute methanol (cooled to about 20C), during which the temperature of the reaction mixture rises to 10C. The batch is stirred for hour at 10C. heated in a water bath to +20 C and stirred on for 1 hour. The solution is then sttirred into 25 liters of aqueous N-hydrochloric acid (about +l0C) and the mixture is stirred for 3/4 hour at 20C, then mixed with 1.9 liters of aqueous tripotassium phosphate solution and adjusted to pH 8.0 with about 20 liters of aqueous ZEN-sodium hydroxide solution. The phases are separated and the aqueous phase is further extracted with 12 liters of methylenechloride. The methylenechloride extracts are combined, dried over 2.5 kg of sodium sulfate and evaporated under vacuum, to yield 1.33kg of residue which is taken up in 570ml of absolute anisole, colled to -15C and, with cooling, 1.66 liters of trifluoroacetic acid are stirred in within 7 minutes. The acid is allowed to react for a total of /2 hour, while maintaining the temperature at about 25C. During the last 5 minutes finely dispersed 7-amino-cephalosporanic acid precipitates from the brownish solution. The solution is then rapidly poured into 20 liters of stirred methanol cooled at 10C. while at the same time adding 2.7 liters of triethylamine. The speed of addition of the trifluoroacetic acid and of the triethylamine should be adjusted so that at no time is there an excess of triethylamine in methanol. The pH value of the mixture is then adjusted to 3.5 with a further 350ml of triethylamine. The batch is kept overnight at 0 to +5C, filtered and the residue is washed by being suspended in the following solvents: 2 X 2 liters of methanol, 2 X 2 liters of methylenechloride and 2 X 2 liters of ether. After drying under vacuum at room temperature, there are obtained 271 g (=81.5% of theory) of 7-amino-cephalosporanic acid. Purity: 100% according to its ultraviolet absorption spectrum (in 0.1N-sodium bicarbonate solution, A max 261 H, e 8500). Specific rotation [a] 114 i 1 (c 1 in 0.5-n sodium bicarbonate).  
 EXAMPLE 21 2.23 g of 7-pheny1acetylamino-cephalosporanic acid benzhydryl ester are dissolved in 100 ml of absolute methylene chloride. The solution is cooled to 20C and treated with 1.55 ml of absolute pyridine and 12.3 ml of an 8% solution of phosphorus pentachloride in methylene chloride. After a reaction period of 15 minutes at 10 to 15C, the solution is again cooled to 20C and then treated with 24.2 ml of absolute methanol. The mixture is then allowed to warm up to room temperature, and allowed to stand for 1 hour. After that, it is poured into 450 ml ofa 2:1 mixture of dioxan and 5% aqueous phosphoric acid, the methylene ch1oride is removed under reduced pressure until the solution is homogeneous. The solution is allowed to stand at 22C for 1 hour, then diluted with 50ml of water, and the dioxan is evaporated under reduced pressure. The aqueous phase is treated with ml of ethanol and the mixture extracted three times with a 5:2 mixture of benzene and ethyl acetate. The organic phases are washed four times with a 1:1 mixture of 2N- hydrochloric acid and ethanol. The aqueous phases are combined and the pH adjusted to 6. The batch is freed from alcohol under reduced pressure and extracted with ethyl acetate at a pH value of 8. The ethyl acetate extract is dried over sodium sulfate and evaporated to obtain 1.45 g (83% of the theory) of 7-aminocephalosporanic acid-benzhydryl ester. The stubstance crystallizes from ether in the form of needles which melt at 126127C. In the UV spectrum in methylene chloride 264 nm (e 7300). 1041f&#34; +4 i 1 ((3 =1 in chloroform). In the thinlayer chromatogram on silica gel in the system ethyl acetate (1:1). Rf 0.31. in toluene+acetone (7:3), Rf 0.39. 438 mg (1 mmol) of 7amino-cephalosporanic acid-benzhydryl ester are dissolved in 5 m1 of anisol. the solution treated with 20 ml of anhydrous trifluoroacetic acid and. after 5 minutes. rapidly evaporated under a pressure of 0.1 mm of Hg. The residue is dissolved in ethyl acetate and the solution extracted with 1% aqueous trifluoroacetic acid. From the aqueous phase which is adjusted to a pH of 3.5 with pyridine, then concentrated to a small volume under pressure. 248 mg 91% of the theoretical quantity) of 7-amino-cephalosporanic acid separate out. According to the thinlayer chromatogram, (on silica gel using the system n-butanolpyridine-glacial acetic acid-water (30:20:6124); Rf: 0.45; brown coloration with ninbydrin-collidine), this acid is unitary and is identical with authentic material. In the microbiological plate test (Staphylococcus aureus) equal inhibition zones are obtained after phenyl-acetylation. The 7-phenylacetyl-amino-cephalosporanic acidbenzhydryl ester used as starting material can be produced as follows: 776 mg of diphenyldiazomethane in 12 ml of dioxane are added to a solution of 780 mg of 7-phenylacetylamino-cephalosporanic acid in 16.5 ml of dioxan. The purpleviolet reaction solution is allowed to stand in the dark at 22C for hours. The then only slightly pink-colored solution is evaporated under reduced pressure, the residue dissolved in 200 ml of chloroform. the chloroform solution washed twice with icecold 5% phosphoric acid, with water, three times with ice-cold N-sodium bicarbonate. and finally with sodium chloride solution. The chloroform solution is then dried over sodium sulfate and evaporated to dryness under reduced pressure. The residue is triturated with ether, then recrystallized from methylene chloride+cyclohexane. The fine colorless needles obtained melt at 113 -l 14C.  
 EXAMPLE 22 1.96 g of desacetoxy-7phenylacetylamino-cephalosporanic acid-benzhydryl ester are dissolved in 100 m1 of absolute methylene chloride. The solution is cooled to 20C and treated with 1.55 ml of absolute pyridine and 12.3 ml of an 8% solution of phosphorus pentachloride in methylene chloride. After a reaction period of minutes at 10 to l5C, the solution is again cooled to C and then treated with 24.2 ml of absolute methanol. The mixture is then allowed to warm up to room temperature, and allowed to stand for 1 hour. After that. it is poured into 450 ml of a 2:1 mixture of dioxan and 5% aqueous phosphoric acid, the methylene chloride is removed under reduced pressure until the solution is homogeneous. The solution is allowed to stand at 22C for 1 hour. then diluted with 50 ml of water. and the dioxan is evaporated under reduced pressure. The aqueous phase is treated with 70 ml of ethanol and the mixture extracted 3 times with a 5:2 mix ture of benzene ethyl acetate. The organic phases are washed four times with a 1:1 mixture of 2N- hydrochloric acid and ethanol. The aqueous phases are combined and the pH adjusted to 6. The batch is freed from alcohol under reduced pressure and extracted with ethyl acetate at a pH value of 8. The ethyl acetate extract is dried over sodium sulfate and evaporated to obtain 1.25 g of desacetoxy-7-amino-cephalosporanic acid-benzydryl ester. The latter is dissolved in 5 ml of anisole. the solution treated with ml of anhydrous trifluoroacetic acid and. after 5 minutes. rapidly evaporated under a pressure of 0.1 mm of Hg. The residue is dissolved in ethyl acetate and the solution extracted with 1% aqueous trifluoroacetic acid. From the aqueous phase which is given a pH of3.5 with triethylamine. then concentrated under reduced pressure to a small volume. and allowed to stand in an ice bath for 2 hours. 790 mg of desacetoxy-7-amino-cephalosporanic acid separate out. The substance is unitary according to thin-layer chromatography (using the system n-hutanol-pyridinc-glacial acetic acid-water (3012016124); Rf=0.48). In the ultraviolet spectrum in 0.1N-sodium bicarbonate it exhibits a maximum at A 263 nm (e 8000). In the IR spectrum it shows no absorption either at 5.75 or 8 l3m,u..  
  The desacetoxy-7-phenylacetyl-aminocephalosporanic acid-benzlhydryl ester can be prepared by the process described by Orin et a1 (J.Am. Chem. Soc. 85, 1896 [1963] by reacting benzylpenicillin-l-oxide benzhydryl ester with a catalytic quantity of anhydrous para-toluenesulfonic acid in xylene at 145C for 10 minutes. The crude product is purified by chromatography on silica gel and elution with methylene chloride+2% ethyl acetate. The ester is recrystallized from methylene chloride-l-cyclohexane and then melts at 178l79C. [a],, 23: 1 (0 1.1 in chloroform). In thin-layer chromatography on silica gel using the system toluene+acetone (3:1), Rf 0.61. In the UV spectrum in 95% ethanol a maximum appears at 258 259 nm (e 6700).  
 EXAMPLE 23 2.75 g of at most 91.5% pure phthalylcephalosporine C [ultra-violet: A 263mp. (e 7,600) in 95% strength ethanol] are suspended in 150 ml of chloroform and dissolved by brief stirring with 1.26 ml of absolute pyridine. After adding 4.42 ml of tri-n-butyl-tin chloride the slightly yellowish-colored solution is allowed to stand overnight at room temperature.  
  It is then cooled to below 20C and 5.43 ml of absolute pyridine are added, followed by 44.3 ml of an 8% strength solution of phosphorus pentachloride in absolute methylene chloride. The mixture is stirred for minutes at 12C. After renewed cooling to below -20C. 60.6 ml of absolute methanol are allowed to run in over the course of a few minutes. After 30 minutes at -10C and a further 30 minutes reaction time at room temperature a clear golden yellow solution is obtained.  
  For purposes of hydrolysis, 10 ml of 25% strength aqueous formic acid are added and the pH-value is raised from 1.6 to 2.0 by adding 1.4 ml of triethylamine. After about 20 minutes stirring at room temperature a fine precipitate begins to separate out. After 2 /2 hours the pH of the suspension is raised to 3.3 by adding a further 9 ml of triethylamine and the mixture is allowed to stand for 90 minutes in an ice bath. The precipitate is filtered off, washed with methanol, methylene chloride and ether and dried in a high vacuum. The resulting colorless 7-ACA, which in the ultra-violet (in 0.1 N NaHCO shows an extinction coefficient at 263 mu of 8,450. cannot be distinguished from authentic 7-ACA by thin layer chromatography.  
 EXAMPLE 24 10 ml of absolute pyridine are added to a solution of 8.1 g of N-phthalyl-cephalosporin c-ditrichlorethylester in 300 ml of methylene chloride and then. in a manner analogous to that described in Example 20, a solution of 6.4 g of phosphorus pentachloride in l 10 ml of methylene chloride is stirred in. In a manner analogous to that of Example 20 the iminoether is formed with 65 ml of methanol. The iminoether is hydrolysed as in Example 20 with 220 ml of l N hydrochloric acid and the batch worlced up as in Example 20. There are obtained 4.3 g of 7-afnino-cephalosporanic acidtrichlorethylester which, accoiding to UV analysis, has a purity of about 79%. That pf&#39;oduct is dissolved in ml of aqueous acetic acid of strength. To the solution are added in portions with vigorous stirring at 20 within 30 minutes 25 g of zih tlust. After stirring clohexylcarbodiimide in 30 ml of acetonitrile is added,  
 at 20, to a solution of 5.5 g of N-phthalylcephalosporin C in 70 ml of acetonitrile and the whole is stirred, with exclusion of moisture, for 1 /2 hours at 20C. 60 ml of 2,2,2-trichlorethanol are added and stirring continued for 48 hours at 20C. Then the batch is evaporated, the residue taken up in ethyl acetate and the solution extracted with aqueous phosphoric acid of 10% strength and then with 0.5M-dipotassiumhydrogenphosphate solution. After drying over sodium sulfate and evaporation there is obtained a crude product which is chromatographed on the thirty-fold amount of silica gel. The ester is eluted with mixtures of benzene and ethyl acetate with increasing content of ethyl acetate. The N-phthalyl-cephalosporin C- ditrichlorethyl ester is pure enough for further reactlon.  
 EXAMPLE 25 To a solution of 2.8 g of cephalosporin C-dibenzyl ester in 130 ml of absolute methylene chloride are added 5.6 ml of pyridine and, within 5 minutes at 20C and under nitrogen, 36.5 ml of phosphorus pentachloride of strength. Stirring is continued for 45 minutes at l0C, then 30 ml of methanol are added and stirring is continued for a further 30 minutes at l0C and for 60 minutes at C. Then 100 ml of l-N. hydrochloric acid are added. After stirring an hour at +10C the pH is adjusted to 7.2 with tripotassium phosphate solution of 50% strength, and the mixture is extracted with methylene chloride. The methylene chloride solution is dried with sodium sulfate and then evaporated. There are obtained 3.1 g of 7-amino-cephalosporanic acid benzyl ester (74% of the theory).  
  The diester used as starting material can be prepared as follows:  
  3.5 g of N-tert.butyloxycarbonyl-cephalosporin C- dibenzyl ester (prepared from N- tert.butyloxycarbonyl-cephalosporin C with diazomethane; m.p.87-88C) are dissolved in 40 ml of trifluoracetic acid, the solution is kept for 5 minutes at room temperature and then evaporated under reduced pressure. the residue dissolved in chloroformether (1:3). washed with 0.5 molar-dipotassiumhydrogenphosphate solution, the organic phase dried over soldium phosphate and evaporated.  
 EXAMPLE 26 A mixture of 7.13 g of the sodium salt of penicillin G (technical grade) in 200 ml of absolute methylene chloride is treated with 3.5 ml of trimethylchlorosilane and stirred for 1 hour at The reaction mixture is then cooled to below l0, treated with 8. l5 ml of absolute pyridine and diluted with a small amount of absolute methylene chloride. A total of 67.5 ml of an 8% solution of phosphorus pentachloride in methylene chloride (=54 g of phosphorus pentachloride) is added within a period of a few minutes. The reaction mixture is stirred for one hour at about l0 then cooled to below 10 and treated drop-wise with 40 ml of absolute methanol. the methanol being added within five minutes. The yellow solution. having a green fluorescence. is stirred at 10 for 30 minutes and then at 0 value adjusted to 4.0 by adding aqueous dipotassium hydrogen phosphate buffer solution. The reaction mixture is cooled in an ice-sodium chloride mixture while stirring slowly, then for about l6 hours at about 4. The  
 &#39; crystalline, slightly yellow precipitate is filtered off and washed with an ice-cold lzl-mixture of water and methanol, with cold methanol and with cold diethyl ether and then dried. The resulting 6-aminopenicillanic acid is uniform according to thin-layer chromatograms on silica gel in the solvent systems nbutanol: acetic acid: water 67:10:23, n-butanol: pyridine: acetic acid: water 38:24:8:30, and ethyl acetate: n-butanol: pyridine: acetic acid: water 42:2l:2l:6:l0  
 EXAMPLE 27 A mixture of 20 g of penicillin V (technical grade) in 200 ml of absolute methylene chloride is treated with 8.3 g of pyridine and 8.6 ml of trimethylchlorosilane. The reaction mixture is stirred for 30 minutes, an additional amount of 27 ml of pyridine is added, and the mixture is cooled to l0, then treated dropwise within a period of ten minutes with 17.8 g of phosphorus pentachloride in 320 ml of dry methylene chloride, while maintaining the temperatur below 0. After cooling to l0, the reaction mixture is treated dropwise with ml of methanol, the addition of the alcohol beeing adjusted in such manner, that the temperature does not rise above 0.  
  The reaction mixture is stirred for 30 minutes at about 1 0 and for 2 hours at about 0 and then diluted with 58 ml of water; the pH is adjusted to about 2.5 with dilute aqueous sodium hydroxide and the mixture is allowed to stand at about 4 for 3 hours. The pH- value is then adjusted to about 4, and after standing for 16 hours, the precipitate, representing the 6-amino penicillanic acid, is filtered off and worked up as shown in example 26.  
 EXAMPLE 28 0.85 g (2 mmol) of penicillin G benzyl ester in 60 ml of absolute methylene chloride are cooled to l0C, and 1.93 ml of absolute pyridine and 1.246 g of phosphoruspentachloride added to the solution. The mixture is left for 1 hour at l0C and then. with cooling with a bath of solid carbon dioxide in isopropanol, 12 ml of absolute methanol are added. The mixture is left for 30 minutes at l0C and for 2 hours at room temperature. With stirring, 40 ml of aqueous 0.5-molar potassium hydrogen phosphate solution are added and the pH is adjusted to 2.2 by means of S-molar phosphoric acid. The mixture is allowed to stand for 20 minutes at room temperature.  
  The pH is then adjusted to 3.3. The aqueous phase is separated and extracted with a mixture of chloroform and ether 1:3, VzV). The combined organic phases are extracted with ice-cold 3% phosphoric acid.  
  The pH of the phosphoric acid solution is adjusted to 8.5 and the product is extracted with ethyl acetate. which is dried over sodium sulphate and evaporated. The colourless, amorphous residue contains 6-aminopenicillanic acid benzyl ester.  
  The infra-red absorption spectrums in methylene chloride show two strong bands at 5.62 and 5.77 a. The substance gives a dirty yellow colour reaction with ninhydrin collidinc.  
 We claim:  
  1. In a process for splitting the acylamino group in a compound of the formula COOR Ac yl NH COOR  in which acyl&#34; is the acyl residue of a carboxylic acid, the group of the formula COOR represents a blocked carboxyl group, and S X is an S- methylene or an S-ethylidene grouping with an agent capable of forming an imide halide to provide a compound of the formula wherein R is said acyl residue of a carboxylic acid devoid of the 0 ll -C- portion and COOR is defined as above, converting the imide halide into the imino ether by treatment with an alkanol or a phenyl-lower alkanol to provide a compound of the formula wherein R is said acyl residue of a carboxylic acid devoid of the portion, R is the residue of an alkanol or phenyl-lower alkanol and COOR is COOR as above and splitting the C=N-double bond of the imino ether by treatment with a hydroxy-group-containing compound.  
  2. A process as claimed in claim 1, wherein phosphorus pentachloride is used as agent forming an imide halide.  
  3. A process as claimed in claim 1, wherein phosphorus oxychloride is used as agent forming an imide halide.  
  4. A process as claimed in claim 1, wherein the reaction with an agent forming an imide halide is carried out in the presence of a tertiary amine,  
  5. A process as claimed in claim 1, wherein the reaction with an agent forming an imide halide is carried out in the presence of pyridine.  
  6. A process as claimed in claim 1, wherein the imide halide is converted into an imino ether by means of a lower alkanol.  
  7. A process as claimed in claim 1, wherein the imide halide is converted into an imino ether by means of methanol.  
  8. A process as claimed in claim 1, wherein the reaction to form the imino ether is carried out under cooling.  
  9. A process as claimed in claim 1, wherein the imino ether is split by hydrolysis under acidic conditions.  
  10. In a process for splitting the acylamino group in a compound of the formula in which acyl is the acyl residue of a carboxylic acid, the group of the formula COOR represents a blocked carboxyl group, and S X is an S-methylene .or an S-ethylidene grouping, to form the corresponding amino group, the step which comprises reacting, in the presence of a base, a compound of the formula in which acyl is the acyl residue of a carboxylic acid, the group of the formula -COOR represents a blocked carboxyl group, and S x is an S-methylene or an S-ethylidene grouping, with an agent capable of forming an imide halide to provide a compound of the formula R2 C:N  
 wherein R is said acyl residue of a carboxylic acid devoid of the out in the presence of pyridine.