PREPARATION OF 5-ACYLAMINO-2,4,6-TRIIODO- OR TRIBROMO-BENZOIC ACID DERIVATIVES

Abstract: A process for the preparation of 5-acylamino-2,4,6-triiodo or tribromo-benzoic acid derivatives of formula (I), wherein X is I or Br, R is H or a variously substituted alkyl, or a group of formula (II), wherein X has the above meanings; Y is hydroxy, alkoxy, hydroxyalkoxy, alkylamino or hydroxyalkylamino; Z may be the same as COY or it is hydroxyalkylaminocarbonyl provided that at least one of the two acyl or R groups is hydroxy-substituted, which process comprises the rearrangement of the corresponding 5-(alkylaminocarbonyl-alkoxy)-2,4,6-triiodo or tribromo-benzoic acid derivatives, in the presence of bases.

Description: Preparation of 5-acylamino-2,4, β-triiodo- or tribromo-benzoic acid derivatives. The invention relates to a new synthetic process, particularly suited for the preparation ■ of 5-acyla- mino-2, 4, 6-triiodo or tribromo-benzoic acid derivatives of formula I CO - Y wherein; X is I or Br, Acyl is a C_-C hydroxyalkanoyl, alkoxyalkanoyl or alkoxy-hydroxyalkanoyl group or a C -C unsubsti- tuted alkanoyl group, is H or a C -C alkyl, hydroxyalkyl, alkoxyalkyl or 1 6 alkoxy-hydroxyalkyl group, or a H(OCH CH ) -, Me(OCH 2 CH 2 ) 2 _ 4 - or Et (OCH 2 CH 2 ) 2 _ 4 ~ group, or a group of formula CO - Y wherein X, Y, Z and Acyl have the same meanings as in formula I and Alkylene- is a straight or branched C -C alkylene 2 o group, which in turn may be substituted by hydroxy groups and/or interrupted by 0,S, SO or SO , Y is a hydroxy, alkoxy, hydroxyalkoxy, alkylamino group or preferably a hydroxyalkylamino group of formula kyl(OH) n wherein R" is H or a C -C alkyl, hydroxyalkyl, alkoxyalkyl or alkoxy-hydroxyalkyl group, Alkyl is a C -C straight or branched alkyl group and n = 1, 2 or 3, Z may have the same meaning of CO-Y in formula I or may be a hydroxyalkylaminocarbonyl group of formula wherein R" , Alkyl and n are as above defined or Z may also be a C -C acylamino, hydroxyacylamino, 2 5 N-alkyl-acylamino, N-hydroxyalkylacylamino or acylaminomethyl group, with the proviso that at least one of the two Acyl or R groups is hydroxy substituted, said process being characterized in that corresponding 5-(alkylaminocarbonyl-alkoxy)-2, 4, 6-triiodo or tribromo- benzoic acid derivatives of formula II, or 5-(acylamino-alkoxy)-2,4, 6-triiodo or tribromo-benzoic acid derivatives of formula III, CO - Y wherein: 1 X and Y have the same meanings as in formula I, Z' may be the same as Z in formula I, but it may also be a group of formula or Acyl-NH-CH -CH-O- Z. J wherein R', R and Acyl are as hereinbelow defined, R' is H or a C -C alkyl, hydroxyalkyl, alkoxyalkyl or 1 6 alkoxy-hydroxyalkyl group or a H(OCH CH ) -, 2 2 2-5 Me(OCH CH ) ■ or Et(OCH CH „ group, or 2 2 2-4 2 2 2-4 group of formula Alk lene- wherein X, Y, Z' are as above defined, R is as herein- below defined, Alkylene- is a straight or branched C -C 2 o alkylene group, which in turn may be substituted by hydroxy groups and/or interrupted by O, S, SO or SO , R is H or a C -C alkyl, hydroxyalkyl or alkoxyalkyl group, Acyl- is a C -C hydroxyalkanoyl, alkoxyalkanoyl or 2 6 alkoxy-hydroxyalkanoyl group or an unsubstituted C -C alkanoyl group, are subjected, in presence of bases, to a rearrangement- reaction to give the desired compounds of formula I. The present invention also relates to 5-acylamino- 2, 4, 6-triiodo or tribromo-benzoic acid derivatives which, having never being disclosed so far, were for the first time obtained by the process described in the present invention. Rearrangment reaction of II and/or respectively III into I is only formally analogous to Smiles rearrangement reaction (Smiles Rearrangement; The MERCK Index, Tenth Edition, Organic Name Reactions, pag. ONR-84) and may be represented as followsr I I I : R ' -NH-CO-CH-O-Ar -i> HO-CH-CO-N ( R ' ) -Ar I I R ι R ι III ■ > I: Acyl-NH-CH -CH-O-Ar Acyl-N-CH -CH-OH 2 I i 2 I R. Ar wherein: R', R and Acyl are as above defined and Ar is a trihalo substituted aromatic ring as defined in formula I . Rearrangment takes place in presence of bases and, generally but not exclusively, at a temperature equal to or higher than room temperature, in order to increase the reaction rate. The equilibrium which takes place between compound II or III and compound I is often so shifted towards I that, by means of the process described in the present invention, yields even higher than 90% may be obtained. Said process is of the greatest interest from the technical point of view since it makes it possible to obtain compounds of formula I, starting from easily available compounds such as the ether derivatives of 5-hydroxy-2, 4, 6-triiodo or tribromo-benzoic acid, said compounds of formula I being very interesting but generally more difficult to obtain in high yields, according to the known methods. Compounds of formula I are valuable components of contrast agents in radiology. Among these, particularly useful are some 5-(N-acyl-amino) -2, 4, 6-triiodo or tribromo-bis- (hydroxy¬ alkyl ) isophthalamide derivatives, since they are non-ionic contrast agents endowed with good tolerability and high water-solubility. Ionic contrast agents used hitherto, are being replaced to a higher and higher extent by this new class of products, since it has a lot of outstanding advantages in particular as far as tolerability is concerned. As in no way limitative examples of non-ionic contrast agents used in radiology, which may be prepared according to the process described in the present invention, the following compounds are hereinbelow reported; Iopamidol = (S) N,N' -bis 2-hydroxy-l-(hydroxymethyl)- ethy 7-5-^ 2-hydroxy-l-oxopropyl)aminq7-2, 4, 6-triiodo-l, 3- benzenedicarboxyamide; Ger. Pat. 2 547 789. Iomeprol = N,N'-bis(2, 3-dihydroxypropyl)-5-/Thydroxy- acetyl)methylamin_7-2, 4, 6-triiodo-l, 3-benzenedicarboxyami- de; Eur. Pat. 26 281. Ioversol '= N,N'-bis(2, 3-dihydroxypropyl)-5- Jhydroxyace- tyl) (2-hydroxyethyl)-amino7-2»-4, 6-triiodo-l, 3-benzenedicar- boxyamide; U.S.A. Pat. 4 396 598. N,N* -bis 2 " -hydroxy-l-(hydroxymethyl)ethyl7-5-ZT2-hydroxy-l- oxopropyl)methylamino7-2, 4, 6-triiodo-l, 3-benzenedicarboxy- amide; Eur. Pat. 26 281. N,N' -bis 2-hydroxy-l-(hydroxymethyl) thyl)methylamino7-2,4, 6-triiodo-l, 3-benzenedicarboxyamide; Eur. Pat. 26 281. 1, 3-bis/N-(3,5-bis-(2,3-dihydroxypropylaminocarbonyl)-2,4, 6 -triiodo-phenyl)-N-hydroxyacetyl-amino7propane; Eur. Pat. 23 992. 1, 4-bis N-( 3, 5-bis-( 1, 3-dihydroxyisopropylaminocarbonyl)- 2,4, 6-triiodo-phenyl)-N-hydroxyacety-_-amino72, 3-dihydroxybu- tane ; Eur . Pat . 23 992 . The process of the invention also make it possible to prepare novel 5-acylamino-2, 4, 6-triiodo or tribromo-benzoic acid derivatives which are part of the disclosure and are useful contrast agents in radiology. The search for novel aromatic tri- or hexa- iodine or bromine derivatives which are water-soluble, well tolerable, non-ionic and useful as radio-opaque agents is so difficult that the achievement of a product fullfilling even only one of such requirements must already be considered as inventive and accordingly patentable. Examples of new compounds which fullfill the above said requirements, and which were obtained according to the process object of the present invention, are hereinbelow reported: - 5-(N-2, 3-dihydroxypropyl-N-hydroxyacetyl-amino)-2, 4, 6- triiodo-bis-(2, 3-dihydroxypropyl ) isophthalamide; - 5-(N-2, 3-dihydroxypropyl-N-hydroxyacetyl-amino)-2,4,6- triiodo-bis-( 1, 3-dihydroxyisopropyl ) isophthalamide; - 5-(N-2, 3-dihydroxypropyl-N- -< -hydroxypropionyl-amino) - 2,4, 6-triiodo-bis-(2, 3-dihydroxypropyl)isophthalamide; - 5-(N-2, 3-dihydroxypropyl-N- C -hydroxypropionyl-amino)- 2,4, 6-triiodo-bis-( 1, 3-dihydroxyisopropyl ) isophthala¬ mide; - 5-(N-l, 3-dihydroxyisopropyl-N-hydroxyacetyl-amino)-2, 4, 6- tribromo-bis-( 1, 3-dihydroxyisopropyl ) isophthalamide; - 5-(N-l, 3-dihydroxyisopropyl-N-hydroxyacetyl-amino)-2,4,6- triiodo-bis-( 1, 3-dihydroxyisopropyl ) isophthalamide; - 5-(N-2-hydroxyethyl-N- -hydroxypropionyl-amino) -2, 4 , 6- triiodo-bis-(2,3, 4-trihydroxy-l-butyl )isophthalamide ; - 5-( -2-hydroxyethy1-N- A -hydroxypropionyl-amino)-2,4, 6- triiodo-bis-(l,3, 4-trihydroxy-2-butyl)isophthalamide; - 5-(N-2-hydroxy-3-methoxypropyl-N-hydroxyacetyl-amino)- 2,4, 6-triiodo-bis-(2,3-dihydroxypropyl)isophthalamide; - 5-(N-methyl-N-hydroxyacetyl-amino)-2,4, 6,-triiodo-bis- (2,3,4-trihydroxy-l-butyl)isophthalamide; - 5-( -methyl-N-hydroxyacetyl-amino)-2,4, 6-triiodo-bis- (1,3,4-trihydroxy-2-butyl)isophthalamide; - 5-(N-2, 3,4-trihydroxy-l-butyl-N-hydroxyacetil)-2,4, 6- triiodo-bis( 2-hydroxyethyl)isophthalamide; - 5-(N-methyl-N-hydroxyacetyl-amino)-2, 4, 6-triiodo-( (N-2, 3- dihydroxypropy1)-(N' -2-hydroxyethyl) )isophthalamide? - 5-(N-2, 3-dihydroxyρropyl-N-hydroxyacetyl-amino)-2,4, 6- triiodo-bis( 2,3-dihydroxyethyl) isophthalate; - 5-(N-methyl-N-hydroxyacetyl-amino)-2, 4, 6-triiodo-bis- (1, 3-dihydroxyisopropyl)isophthalate; - 1, 3-bis-(N-( 3, 5-bis( 1, 3-dihydroxyisopropylaminocarbonyl) -2,4, 6-triiodo-phenyl)-N-hydroxyacetyl-amino)-2-hydroxy- propane; - 1, 3-bis-(N-(3,5-bis(2,3-dihydroxypropylaminocarbonyl)- 2,4, 6-triiodo-phenyl)-N-hydroxyacetyl-amino)-2-hydroxy- propane; - l,6-bis-(N-( 3, 5-bis(2, 3-dihydroxypropylaminocarbonyl)- 2,4, 6-triiodo-phenyl)-N-hydroxyacetyl-amino)-2, 3,4, 5- tetrahydroxy-hexane; - 1,7-bis-(N-(3, 5-bis(1, 3-dihydroxyisopropylaminocarbony1) -2,4, 6-triiodo-phenyl)-N-hydroxyacetyl-amino)-2, 6-dihy- droxy-4-oxa-heptane; - l,5-bis-(N-(3, 5-bis(2, 3-dihydroxypropylaminocarbonyl) -2,4,.6-triiodo-phenyl)-N-hydroxyacetyl-amino)-3-thia- pentane ; - l,5-bis-(N-(3,5-bis(2, -dihydroxypropylaminocarbonyl )- 2,4, 6-triiodo-phenyl )-N-hydroxyacetyl-amino)-3-thia-pen- tane-3-oxide; - 1, 5-bis-(N-( 3, 5-bis( 2, 3-dihydroxypropylaminocarbonyl )- 2,4, 6-triiodo-phenyl )-N-hydroxyacetyl-amino)-3-thia-pen- tane-3, 3-dioxide; - l,3-bis-(N-(3-(2, 3-dihydroxypropylaminocarbonyl )-5-( 2-hy- droxyethylaminocarbonyl ) -2, 4, 6-triiodo-phenyl )-N-hydroxy- acetyl-amino)-2, 2-bis-(hydroxymethyl )-propane; - l,3-bis-(N-(3-(l, 3-dihydroxyisopropylaminocarbonyl )-5- ( 2-hydroxyethylaminocarbonyl )-2, 4, 6-triiodo-phenyl ) -N- hydroxyacetyl-amino)-2, 2-bis-(hydroxymethyl )-propane; - 3, 5-bis-(N-methyl-N-hydroxyacetyl-amino)-2,4, 6-triiodo- (2, 3-dihydroxypropyl )benzamide; - 3, 5-bis-(N-methyl-N-hydroxyacetyl-amino) -2,4, 6-triiodo- ( 1, 3-dihydroxyisopropyl )benzamide; - 3, 5-bis-(N-methyl-N- < -hydroxypropionyl-amino)-2, 4, 6- triiodo-( 1, 3-dihydroxyisopropyl )benzamide; - 3, 5-bis-(N-2-hydroxyethyl-N-hydroxyacetyl-amino) -2, 4 , 6- triiodo-(2, 3-dihydroxypropyl )benzamide; - 3, 5-bis-(N-2-hydroxyethyl-N-hydroxyacetyl-amino)-2, 4, 6- triiodo-( 1, 3-dihydroxyisopropyl )benzamide; - 3, 5-bis-(N-2-hydroxyethyl-N- <? • - -hydroxypropionyl-amino)- 2,4, 6-triiodo-( 2, 3-dihydroxypropyl )benzamide; - 3, 5-bis-(N-2-hydroxyethyl-N- c -hydroxypropionyl-amino)- 2,4, 6-triiodo-( 1, 3-dihydroxyisopropyl )benzamide; - 3, 5-bis-(N-2-hydroxyethyl-N-hydroxyacetyl-amino)-2, 4 , 6- triiodo- ( 2-hydroxyethyl )benzamide; - 3, 5-bis-(N-2-hydroxyethyl-N-hydroxyacetyl-amino) - 2 , 4, 6- triiodo-(N,N-bis-( 2-hydroxyethyl) )benzamide; - 3, 5-bis-(N-2-hydroxyethyl-N-hydroxyacetyl-amino)-2, 4, 6- triiodo-(2-hydroxyethyl)benzoate; - 3, 5-bis-(N-2-hydroxyethyl-N-hydroxyacetyl-amino)-2,4, 6- triiodo-(2, 3-dihydroxypropyl)benzoate; - 3-(N-2-hydroxyethyl-N-hydroxyacetyl-amino)-5-acetylami- no-2, 4, 6-triiodo-(2, 3-dihydroxypropyl)benzamide; - 3-(N-2-hydroxyethyl-N-hydroxyacetyl-amino)-5-(N-metyl-N- acetyl-amino)-2, 4, 6-triiodo-(2, 3-dihydroxypropyl)benza- mide; - 3-(N-2-hydroxyethy1-N-hydroxyacetyl-amino)-5-acetylami- nomethyl-2, 4, 6-triiodo-( 2, 3-dihydroxypropylJbenzamide; - 3-( -2-hydroxyethyl-N-hydroxyacety1-amino)-5-acetylami- nomethyl-2,4, 6-triiodo-( 2-hydroxyethyl)benzoate; - 5-(N-2-hydroxyethyl-N-hydroxyacetyl-amino)-2, 4, 6-tri¬ iodo-bis-(N,N-bis( 2-hydroxyethyl ) ) isophthalamide; - 5-( -2, 3-dihydroxypropy1-N-hydroxyacetyl-amino)-2 ,4, 6- triiodo-bis-(N,N-bis(2-hydroxyethyl) ) isophthalamide; - 5-(N-2-hydroxyethyl-N- ft -hydroxypropionyl-amino)-2 , 4, 6- triiodo-bis-(N,N-bis(2-hydroxyethyl) )isophthalamide; - 5-(N-2-hydroxyethy1-N-hydroxyacetyl-amino)-2,4, 6-tri- iodo-bis-(N-2, 3-dihydroxypropyl-N-2-hydroxyethyl) isoph¬ thalamide; - 5-(N-2-hydroxyethyl-N-hydroxyacetyl-amino)-2, 4,6-tri- iodo-bis-(N-l, 3-dihydroxyisopropyl-N-2-hydroxyethyl)- isophthalamide; - 5-(N-methyl-N-hydroxyacetyl-amino)-2 ,4, 6-triiodo-bis-(N- 1, 3-dihydroxyisopropyl-N-2-hydroxyethyl) isophthalamide; - l,3-bis-(N-(3,5-bis-(N,N-bis( 2-hydroxyethyl)aminocarbo- nyl)-2,4, 6-triiodo-phenyl)-N-hydroxyacetyl-amino)-2- hydroxy-propane ; - l,3-bis-(N-(3,5-bis-(N,N-bis( 2-hydroxyethyl )aminocarbo¬ ny1 )-2 , 4 , 6-triiodo-phenyl )-N-hydroxyacetyl-amino) - propane; - 1, 3-bis- (N-( 3, 5-bis-(N,N-bis-( 2-hydroxyethyl laminocarbo- nyl ) -2 , 4 , 6-triiodo-phenyl )-N-hydroxyacetyl-amino) -2, 2- bis-(hydroxymethyl )-propane; - l,4-bis-(N-(3,5-bis-(N,N-bis ( 2-hydroxyethyl )aminocar o- nyl ) -2, 4 , 6-triiodo-phenyl ) -N-hydroxyacetyl-amino) -2 , 3- dihydroxy-butane; - 1, 4-bis-(N-( 3, 5-bis-(N,N-bis( 2-hydroxyethyl )aminocarbo- nyl)-2,4,6-triiodo-phenyl)-N-^ -hydroxypropionyl-amino)- -2, 3-dihydroxy-butane; - l,4-bis-(N-(3,5-bis-(N-l, 3-dihydroxyisopropy1-N-2-hydro- xyethyl-aminocarbon 1)-2, 4, 6-triiodo-phenyl )-N-hydroxy¬ acetyl-amino)-2, 3-dihydroxy-butane; - l,4-bis-(N-(3,5-bis-(N-l, 3-dihydroxyisopropyl-N-2-hydro¬ xyethyl-aminocarbony1 )-2, 4, 6-triiodo-phenyl)-N- c -hydro¬ xypropionyl-amino)-2, 3-dihydroxy-butane; - 1, 5-bis-( -( 3, 5-bis-(N,N-bis ( 2-hydroxyethyl )aminocarbo- nyl )-2, 4, 6-triiodo-phenyl ) -N-hydroxyacetyl-amino) -3-oxa -pentane ; - l,5-bis-(N-(3,5-bis-(N,N-bis( 2-hydroxyethyl ) aminoca bo¬ ny1 ) -2, 4, 6-triiodo-phenyl) -N-hydroxyacetyl-amino) -3- thia-pentane. In compounds of formula I, Acyl preferably is a 2-hydroxyalkanoyl group. Acyl-N(R)- in turn preferably represents a hydroxyacetylamino, " c{-hydroxypropionylamino, N-methyl-hydroxyacetylamino, L-N-methyl- -hydroxypropio- nylamino, N-ethyl-hydroxyacetylamino, N-ethyl- c -hydroxy- propionylamino, ^-hydroxybutyrroylamino, N-methyl- -hy- droxybutyrroylamino, N-2-hydroxyethyl-hydroxyacetylamino, N-2, 3-dihydroxypropyl-hydroxyacetylamino, N-l, 3-dihy¬ droxyisopropyl-hydroxyacetylamino-N-2-hydroxy-3-methoxy- propyl-hydroxyacetylamino, N-2-hydroxy-3-ethoxypropyl- hydroxyacetylamino, N-2-methoxyethyl-hydroxyacetylamino, N-2-ethoxyethyl-hydroxyacetylamino, N-2-hydroxyethyl- (~ - hydroxypropionylamino ,N-2-hydroxyethy1-N- ( ,β-dihydroxy- propionylamino group. Acyl' may also be an unsubstituted or an alkoxysubstituted alkanoyl group, preferably an ^cetyl group, in such case R necessarily carrying a hydroxy group. Some examples of possible substituents in 5-position are the following: N-2-hydroxyethyl-acetylamino, N-2-hydroxyethyl-propionyl- amino, N-2-hydroxypropyl-acetylamino, N-2-hydroxy-3-me- thoxypropyl-acetylamino, N-2-hydroxyethyl-methoxyacety1- amino. R may also be a polyoxyethylene group of formula: H(OCH CH )_ -, Me(OCH CH ) -, or Et(OCH_CH_ ) _ -. 2 2 2-5 2 2 2-4 2 2 2-4 Y in compounds of formula I, II and III may be: hydroxy, alkoxy or hydroxyalkoxy, as for example methoxy, ethoxy, 2-hydroxyethoxy, 2, 3-dihydroxypropoxy, 1, 3-dihydroxyisopropoxy, or alkylamino such as methylamino, or preferably a hydroxyalkylamino group of formula: . R" - N Alkyl ( OH ) n wherein R" , Alkyl and n have the above mentioned meanings. Examples of such group are the following ones: 2-hydroxyethylamino, 2-hydroxypropylamino, 2,3-dihydro- xypropylamino, 1, 3-dihydroxyisopropylamino, 1, 3-dihydro¬ xy-2-methy1-isopropylamino, 2,3, 4-trihydroxy-l-butylamino, 1,3, 4-trihydroxy-2-butylamino, 1, 3-dihydroxy-2-hydroxyme- thyl-isopropylamino, N-methyl-N-2-hydroxyethylamino, N-methyl-N-2, 3-dihydroxypropylamino, N-methyl-N-1, 3-di¬ hydroxyisopropylamino, N-2-hydroxyethyl-N-2, 3-dihydroxy- propylamino, N-2-hydroxyethyl-N-l, 3-dihydroxyisopropylami¬ no, N, N-bis-( 2-hydroxyethyl )amino, N,N-bis-( 2, 3-dihydroxy- propyl ) amino, N, -bis-( 1, 3-dihydroxyisopropyl )amino. Z substituent in 3-position is preferably equal to -CO-Y in 1-position, but may also be a hydroxyalkylaminocarbonyl group of formula: wherein R" , Alkyl and n have the above mentioned meanings. Z can also be an acylamino group, such as acetyl- amino, propionylamino, or a hydroxyacylamino group, such as hydroxyacetylamino, ^,-hydroxypropionylamino, or a N-alkyl-acylamino group, such as N-methyl-acetylamino, N-methyl-hydroxyacetylamino, or a N-hydroxyalkyl-acetyl- amino group, such as N-2, 3-dihydroxypropyl-acetylamino, N-1, 3-dihydroxyisopropyl-acetylamino, N-2-hydroxyethyl-hy- droxyacetylamino, or an acylaminomethyl group, such as acetylaminomethyl or hydroxyacetylaminomethyl of formula: HO-CH -CONH-CH - 2 2 In the starting compounds of formula II, the sub¬ stituent in the 5-position is an aminocarbonyl-alkoxy or alkylaminocarbonyl-alkoxy group, of which the following examples are reported: aminocarbonyl-methoxy NH ^ COCH ^ O- 2 2 1-aminocarbonyl-ethoxy NH COCH(Me)0- methylaminocarbonyl-methoxy MeNHCOCH O- 2 1-(methylaminocarbonyl)-ethoxy MeNHCOCH(Me)0- ethylaminocarbony1-methoxy EtNHCOCH 0- 2 1-(ethylaminocarbonyl)-ethoxy EtNHC0CH(Me)0- ( 2-hydroxyethylaminocarbonyl )-methoxy HOCH CH NHCOCH O- 2 2 2 1-(2-hydroxyethylaminocarbonyl)- ethoxy HOCH CH NHCOCH(Me)0- ( 2--methoxyethylaminocarbonyl)-methoxy MeOCH CH NHCOCH 0- 1-(2-methoxyethylaminocarbony1)- ethoxy MeOCH CH NHCOCH(Me)0- 1-(methylaminocarbonyl)-2-methoxy- ethoxy MeNHCOCH(CH OMe)0- l-(methylaminocarbonyl)-2-ethoxy- ethoxy MeNHCOCH(CH OEt)0- (2, 3-dihydroxypropylaminocarbonyl)- methoxy HOCH CH(OH)CH NHCOCH O- (2-hydroxy-3-methoxy-propylamino- carbonyl)-methoxy MeOCH CH(OH)CH NHCOCH O- In the starting compounds of formula III, the substituent in 5-position is an acylamino-alkoxy group. That makes it possible to prepare a compound of formula I, in which Acyl has no hydroxy groups, in such case R necessarily carrying a hydroxy substituent. Since said hydroxy groups are desirable, because of their ability to increase water-solubility, also both Acyl and R can be substituted by said functional groups. According to what hereinabove stated, non limitative examples of the group of formula Acyl-NH-CH CH(R )-O- in compounds of formula III, in which R and Acyl are as above defined, are the following ones: 2-acetylamino-ethoxy AcNHCH CH O- 2 2 2-hydroxyacetylamino-ethoxy HOCH CONHCH CH 0- 2-acetylamino-propoxy AcNHCH(Me)CH O- 2-acetylamino-l-(methoxymethyl)ethoxy AcNHCH CH(CH OMe)O- 2- H -hydroxypropionylamino-ethoxy HOCH(Me )CONHCH CH O- 2-acetylamino-1-methyl-ethoxy AcNHCH CH(Me)0- 2-methoxyacetylamino-ethoxy MeOCH CONHCH CH O- 2-methoxyacetylamino-1-hydroxymethyl- ethoxy MeOCH CONHCH CH(CH OH)O- According to the general definition of formula I, by means of the process of the present invention, , UJ -bis-(N-2, 4, 6-triiodo or tribromo-phenyl-N- <X -hydroxy acyl-amino)alkanes of formula VI CO-Y CO-Y wherein: X, Y and Z have the same meanings of formula I, Alkylene is a straight or branched ~ m .~~ alkylene 2 8 residue, which in turn may be substituted by hydroxy groups and/or interrupted by O, S, SO or so 2 , R is H or a C -C alkyl, hydroxyalkyl, alkoxyalkyl or alkoxy-hydroxyalkyl group, can also be prepared. The above said compounds of formula VI are obtained by a double rearrangement from the corresponding bis-(N-( 2, 4, 6-triiodo or tribromo-phenoxyacyl)-amino)-al- kanes of formula VII CO-Y CO-Y VII wherein Y, Z, R and Alkylene have the same meanings as in formula VI. From the 3, 5-bis-ethers of formula VIII, by a double rearrangement, the corresponding 3, 5-bis-acylamino-2, 4, 6-triiodo or tribromo-benzoic acid derivatives of formula IX can be prepared, according to the following scheme: CO-Y R l R ι wherein X, Y, R and R have the same meanings as in formulae I and II, respectively. From the 3, 5-bis-ethers of general formula X, by double rearrangement, the corresponding 3, 5-bis-acylamino-2, 4, 6-triiodo or tribromo-benzoic acid derivatives of general formula XI can be prepared, according to the following scheme: CO-Y wherein X, Y, Acyl and R have the same meanings as in formulae I, II and III, respectively. By means of the process of the present invention, the 3, 5-bis-acylamino-2, 4, 6-triiodo or tribromo-benzoic acid derivatives of general formula XIII, can also be prepared by rearrangement of the corresponding compounds of formula XII, according to the following scheme: wherein : X and Y have the same meanings as in formula I, A and B, which may be the same or different, are groups of formula -N(R)C0-CH0H-R or -N(Acyl)CH -CHOH-R respectively defined as in formulae IX and XI, B' is a group of formula -CH(R )CONHR or -CH(R )CH - -NH-Acyl respectively defined as in formulae VIII and X. Starting compounds necessary to carry out the synthetic process according to the invention are 5- ( alkylaminocarbonyl-alkoxy) -2, 4 , 6-triiodo or tribromo- benzoic acid derivatives of formulae II or VII, 5-(acyl¬ amino-alkoxy)-2,4, 6-triiodo or tribromo-benzoic acid deri¬ vatives of formula III, 3, 5-bis-(alkylaminocarbonyl-al¬ koxy)-2, 4, 6-triiodo or tribromo-benzoic acid derivatives of formula VIII, 3,5-bis-(acylamino-alkoxy)-2, 4, 6-triodo or tribromo-benzoic acid derivatives of formula X, 3-(alkyl- aminocarbonylalkoxy or acylaminoalkoxy)-5-acylamino-2, 4, 6- triodo or tribromo-benzoic acid derivatives of formula XII. By means of known synthetic methods, the above cited 5-hydroxy-2, 4, 6-triodo or tribromo-benzoic acid ether derivatives of formulae II, III, VII, VIII, X and XII are generally more easily obtainable than compounds of formula I. The more evident advantage of this new synthetic process resides in that the above said contrast agents can be usually prepared more easily and in a shorter way, when compared to known methods. In order to prepare non-ionic contrast agents, generally consisting in 5-hydroxyacylamino or 5-(hydroxyalkylacylamino)-2, 4, 6-triiodo or tribromo- bis-(hydroxy-alkyl)isophthalamides, by means of known synthetic methods, the proper intermediates are usually subjected to acylation and/or alkylation at the aromatic nitrogen in 5-position, thus obtaining the corresponding anilides and/or alkylanilides. An xmdesired even if partial reaction of the hydroxy groups present in the molecule with the acylating or the alkylating agent, to give the corresponding O-acetyl or O-alkyl derivatives, is in such way inevitable. This makes the purification of the final products quite difficult, or requires the use of appropriate protecting groups, in order to preserve the hydroxy groups from said side reactions. By the process of the invention, on the contrary, the use of such protecting groups is no more necessary, since acylating or alkylating agents are not used. Synthetic schemes illustrating respectively the process of the invention (Fig. No. 1) in comparison with a known synthesis of Ioversol (Fig. No. 2, USA Pat. 4.396.598) are hereinbelow enclosed as an example. The above said advantages of easiness and shortness of the synthesis, besides the ones deriving from avoiding the use of dangerous and polluting reactants, such as thionyl chloride, or large amounts of acetic anhydride and soda to protect and subsequently deprotect hydroxy groups, are immediately evident from a comparative examination of the two processes. Another favourable aspect of the process resides in the remarkable easiness of the purification steps, because of the minimum amounts of salts to be removed, while, using known synthetic methods, long and expensive separation techniques are required in order to remove large amounts of such impurities. Up to now, such rearrangement reactions of compounds of formulae II and III have never been disclosed. Only a merely formal comparison may be done with Smiles rearrangement reaction, although remarkable differences exist even in comparison with the most similar examples of said reaction. In this respect, see the following enclosed references: W.E. Truce et al. Organic Reactions 18, 99-215 (1970); J.F. Bunnet et al, Chemical Reviews 49, 362 (1951); G .G . ubbels et al, J. er.Chem.Soc.102, 4848, 4849( 1980) E.A. Nodiff et al, J. Org. Chem. 29, 2453-2455 (1964); G.E. Bonvicino et al, J. Org. Chem. 27, 4272-4280 (1962); .R. Baker, J. Org. Chem. 48, 5140-5143 (1983). The rearrangement reaction can be carried out in water or in an organic solvent such as methanol, ethanol, isopropanol, 2-methoxyethanol, 1,2-dimethoxyethane, 1, 2-propanediol, tetrahydrofuran (THF), benzene, toluene, pyridine or dimethylsulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAC) or hexamethylphosphoramide (HMPT), generally in the presence of only catalytic amounts of bases. Alkali, such as sodium hydroxide, potassium hydroxide, lithium hydroxide, alkali metal carbonates (Na CO , K CO ) , alkali metal hydrogenocarbonates (NaHCO , KHCO ) , alkali metal borates such as borax or sodium bora- te r and corresponding buffer mixtures, alcoholates such as sodium ethylate, sodium methylate, potassium ethylate, potassium methylate, potassium tert-butylate, tertiary amines such as triethylamine, tributylamine, N-methyl-mor- pholine, N-methyl-pyrrolidine, N-methyl-piperidine, quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammo- nium hydroxide, tetrabutylammonium fluoride, benzyltrimetylammonium hydroxide, diazabicycloundecene (DBU), and tetraazacyclododecane (TAZA) can be used as bases . Bases such as sodium amide and potassium amide, as well as alkali hydrides such as sodium hydride or potassium hydride, can also be considered as potentially useful. Sometimes addition of crown ethers can also be useful to remarkably increase the reaction rate. Reaction temperature may generally range from 0° to 150°C, preferably from 50° to 100°C; it strongly depends on the kind of solvent and base used; for example, in presence of sodium hydride or, even better, of potassium hydride, the reaction proceeds in an aprotic solvent such as DMF or DMAC at a very high rate at 0°C or even at lower temperatures. Favourable conditions to increase reaction rate are attained carrying out the reaction in the presence of an alkali hydride in an ether, such as 1, 2-dimethoxyethane, THF, or in an aprotic solvent, adding a crown ether such as 15-crown-5-(=1,4,7,10, 13-pentaoxacyclopentadecane ) , 18-crown-6 ( =1, 4, 7, 10, 13, 16-hexaoxacyclooctadecane ) . Fig- © ■ + soeε. —L CH C0C2. → CH j CO^CHCO^H I 50C2 Λ → CH <_ ■ < *** , CH, CO < * ≤- Fig. 2 (following) rtoL. OH O-HCM CHOMCK "* . C«, EXAMPLE 1 ( S ) 5-/_{ 2-hydroxypropionyl ) -amino/- , 4, 6-triiodo-bis-( 1, 3- dihydroxyisopropyl ) isophthalamide . ( Iopamidol ) . 11 g of ( S) 5-( 1-aminocarbonyl-ethoxy ) -2, 4-6-triiodo-bis- ( 1, 3-dihydroxyisopropyl ) isophtalamide (0,0141 mole) were dissolved in 110 ml of DMF. 3,6 ml of a 4 M solution of CH ONa in CH OH (0,0144 mole) were dropped therein at room temperature. The reaction was complete after 65 hours (T.L.C. control: silica gel Merck plate 60F__ Eluent = 254 CHC1 6, CH OH 3, NH OH 25% 1. Developer: starch (254 nm) ) . The reaction mixture was neutralized with HCl/CH OH 4M (3.6 ml; 0,0144 mole) and, after filtration of the salts, evaporated under reduced pressure. The crude product was solidified by treatment with CH Cl then, after filtration, was dissolved in water, percolated on Amberlite IR120 and Dualite A30B and eluted with water. The neutral aqueous layer was evaporated and the crude compound was crystallized from absolute ethanol . 9.5 g of (S)- 5 12-hydroxypropionyl ) -amino7-2, 4, 6- triiodo-bis( 1, 3-dihydroxyisopropyl ) isophthalamide (0,0122 mole) were obtained. Yield 86.6% m.p. 297°C HPLC purity 99.4% °i_7 ? c = -139,08° (c = 1,25% as cupric complex) : (theor. 436 -143°C) . Optical purity: 97.2% Elemental Analysis Calc. % : C 26.28; H 2.85; I 48.99; N 5.41 Found % : C 26.27; H 2.85; I 48.91; N 5.36 IR; H and C NMR spectra were in agreement, with the proposed structure. A) Preparation of R-5- ( 1-aminocarbonyl-ethoxy ) -2 , 4 , 6- triiodo-bis-( 1, 3-dihydroxyisopropyl ) isophthalamide. 35 g of R-5-( 1-ethoxycarbonyl-ethoxy ) -2 , 4 , 6-tri¬ iodo-bis-( 1, 3-dihydroxyisopropyl ) isophthalamide (0.0434 mole) (Eur. Pat. Appl. 185130) were heated to 80°C under pressure in NH /CH OH 7N (0.63 mole) for 2.5 hours. Then the reaction mixture was evaporated to dryness and the resulting product was crystallized from absolute ethanol to give the desired product. 23 g of R-5-( 1-aminocarbonyl-ethoxy ) -2 , 4 , 6-triiodo- -bis- ( 1, 3-dihydroxyisopropyl ) isophthalamide (0.0296 mole) were obtained. Yield: 68.2% ; m.p. 110° ; HPLC purity 99.7%. Elemental Analysis Calc. % : C 26.28; H 2.85; I 48.99; N 5.41 Found % : C 26.78; H 2.91; I 48.63; N 5.32 IR; H and C NMR spectra were in agreement with the proposed structure. EXAMPLE 2 -5- j2-hydroxypropionyl)methylamino_7-2, 4, 6-triiodo-bis- ( 1, 3-dihydroxyisopropyl) isophthalamide. According to the procedure of example 1, 39 g of S_-5-(1-methylaminocarbonyl-ethoxy)-2, 4, 6-triiodo-bis-( 1,3- dihydroxyisopropyl)isophthalamide (0.0493 mole) in 390 ml of DMF were reacted with CH ONa/CH OH 4 M (12.3 ml; 0.0493 mole) at room temperature. When the conversion was ,complete (T.L.C. control: silica gel Merck plate 60 F ^ c /Eluent = CHCl., 6; CH..OH 3; NH OH 25% 1), the reaction 254 3 3 4 mixture was worked as described in example 1, to give the desired compound. 27.5 g of S-5-/( 2-hydroxypropionyl )methylamino7- 2,4,6-triiodo-bis-(1, 3-dihydroxyisopropyl) isophthalamide (0.0347 mole) were obtained. Yield: 70.4%; m.p. 250°C. Analysis: Calc. %: I 48.12 Found %: I 47.99 EXAMPLE 3 5-(N-2-hydroxyethyl-N-hydroxyacety1-amino) -2,4, 6-triiodo- bis-(2,3-dihydroxypropyl) isophthalamide. (Ioversol ) . 17.4 g of 5-( 2-hydroxyethyl ) -aminocarbonylmethoxy- 2,4, 6-triiodo-bis-( 2, 3-dihydroxypropyl ) isophthalamide (EP-A-0.185.130, Ex. 31) (0.0216 mole) were heated to 90°C in 375 ml of water. The pH of the solution was adjusted to 9 by addi¬ tion of 0.05 N NaOH and the reaction was monitored by T.L.C. After 5 hours, about 70-75% of the starting compound was transformed into the final product. After neutralization with 0.05 N HC1, solvent was concentrated; upon cooling the major part of the unreacted starting compound crystallized and was filtered off. The filtrate containing the title compound was made free from salts by ion-exchange resins. The final crude product was eventually purified on Amberlite XAD-2. 11.91 g of the desired compound were obtained (0.0148 mole). Yield 681 ; m.p.: 195°C ; HPLC Purity: 99% . The characteristics of the obtained compound were in agreement with those of the derivative described in EP-A-0.083.964. EXAMPLE 4 5-( -2, 3-dihydroxypropy1-N-hydroxyacetyl-amino)-2, , 6-tri¬ iodo-bis- ( 2, 3-dihydroxypropyl ) isophthalamide . 21 g of 5-( 2, 3-dihydroxypropyl )aminocarbonylmethoxy-2, 4 , 6- -triiodo-bis-( 2, 3-dihydroxypropyl ) isophthalamide ( EP-A- 0.185.130, Ex.: 32) (0.0251 mole) were heated to 90°C in 650 ml of water. pH was adjusted to 9 by addition of 0.05 M NaOH. Disappearance of the starting compound and formation of the final one were monitored by T.L.C. After 5 hours the reaction mixture was cooled, neutralized with 0,05 M HC1 and concentrated. The unreacted starting compound was crystallized off, and the filtrate was made free from salts by ion-exchange resins. The obtained crude product was purified as described in example 1. 10.1 g of the final compound (0.0121 mole) were obtained. Yield: 48% ; m.p. 195-200°. Elemental Analysis Calc. % : C 27.26; H 3.13; I 45.48; N 5.02 Found % : C 26.71; H 3.26; I 45.35; N 4.88 EXAMPLE 5 5-(N-methyl-N-hydroxyacetyl-amino)-2, 4, 6-triiodo-bis-( 2, 3- dihydroxypropyl) isophthalamide. (Iomeprol) 40 g of 5-methylaminocarbonylmethoxy-2, 4 , 6-tri¬ iodo-bis-( 2, 3-dihydroxypropyl)isophthalamide (EP-A-0.185. 130, Ex.: 30) (0,0515 mole) were heated to 90°C in water and pH was adjusted to 9 by addition of 0,05 M NaOH. The reaction was monitored by T.L.C. After about 4.5 hours, the reaction mixture was neutralized by means of 0.05 M HC1, then the final compound was purified as described in example 1. 34.15 g of the final compound were obtained (0.0439 mole) . Yield: 85% m.p. 280-282°C, with decomposition. Elemental Analysis Calc. % : C 26.27; H 2.85; I 48.99; N 5.41 Found % : C 26.18; H 2.87; I 48.99; N 5.39 The product was corresponding to the one described in EP-A-0 . 062 . 281 , Ex . : 9 . EXAMPLE 6 5-(N-methyl-N-hydroxyacetyl-amino)-2, 4 , 6-triiodo-bis-(2,3- dihydroxypropyl ) isophthalamide. 4 g of 5-methylaminocarbonylmethoxy-2, 4, 6-triiodo- bis-( 2, 3-dihydroxypropyl ) isophthalamide (0.0051 mole) in 40 ml of DMAC were mixed at 25°C with 1 equivalent of potassium hydride and 18-crown-6-( =1, 4 , 7, 10, 13, 16-hexa- oxacyclooctadecane ) . The reaction was monitored by T.L.C. After 1 hour, a conversion of about 75% was obtained. Solvent was evaporated under reduced pressure, then purification and recovery of the final compound were carried out according to the procedure described in example 1. 2.3 g of the final product were obtained (0.0033 mole ) . Yield: 64.3% m.p. 280-283°C with decomposition. EXAMPLE 7 l,3-bis-(N-(3,5-bis-(2, 3-dihydroxypropylaminocarbonyl )- 2,4, 6-triiodo-phenyl ) -N-hydroxyacetyl-amino) -propane . 5.8 g of 1, 3-bis- ( 3, 5-bis ( 2 , 3-dihydroxypropylaminocar¬ bonyl ) -2, 4, 6-triiodo-phenoxy-acetylamino) -propane (obtain- ed according to the general procedure disclosed in EP-A-185.130) (0.0037 mole) were suspended in 1160 ml of 0.022 M borate buffer and heated to 95°C, with constant control of pH (pH=9). A conversion of 70.22% (determinated by HPLC) was obtained after about. 3 hours. Following the procedure described in example 1, the reaction mixture was then cooled to room temperature, made free from salts and purified to give the desired compound. 3.2 g of 1, 3-bis-(N-(3, 5-bis-(2, 3-dihydroxypropyl- aminocarbonyl)-2, 4, 6-triiodo-phenyl)-N-hydroxyacetyl-ami- nolpropane (0.002 mole), were obtained. Yield: 54% ; m.p. 234-236°C with decomposition. Analysis Calc. % : I 48.61 Found % : I 48.23 T.L.C. Rf = 0.27 (Eluent: butanol/AcOH/H 0 = 15:3:5) HPLC; Rt = 14 minutes; Visualizer: UV (254 nm) Lichrosorb RP18 5 u - (250X4) Column Temperature: 60°C Eluent (gradient): A - KH PO, O.0125 M 2 4 B = CH CN/H 0 1/1 v/v Time (min. ) : 0 ; 5; 30; 50; % B : 1; 5; 20; 75; The general procedure followed in examples 8 to 27 to study the progress of the reaction with the change of various parameters thereof (solvent, base, temperature) is herein reported. The results are hereinbelow summarized in Table 2. EXAMPLES 8-27 5-(N-methyl-N-hydroxyacetyl-amino) -2,4, 6-triiodo-bis-(2,3- dihydroxypropyl) isophthalamide. 5-methylaminocarbonylmethoxy-2, 4, 6-triiodo-bis-(2,3- dihydroxypropyl ) isophthalamide was dissolved or suspended in the solvent in a reactor, provided with a refrigerant with a KOH valve and under nitrogen atmosphere, and the mixture was stirred at a temperature ranging from 25°C to 95°C. The selected base, generally in an equimolecular amount to the starting product, was added to the solution (Method A) or to the suspension (Method B). The reaction was monitored by T.L.C. or HPLC (analytical conditions are hereinbelow specified in Table 1) and conversion percentages and reaction times were evaluated and reported in table 2. The characteristics of the obtained 5- (N-methyl-N- hydroxyacetyl-amino) -2,4, 6-triiodo-bis-( 2 , 3-dihydroxypro¬ pyl ) isophthalamide were in agreement, with those of the product described in EP-0.026.281 , Ex.: 9. TABLE 1 1) T.L.C. ponditions: Support = Merck silica gel plate 60 F 254 Eluent = A: chloroform 6, ethanol 3, ammonia 25% 1 B: chloroform 70, methanol 30, acetic acid 2 C: 2-butanone 15, acetic acid 3, water 5 Developer = starch and exposition to UV light ( 254 nm) . 2) H.P.L.C. conditions : Eluent (gradient) Solvent A = KH PO„ 0.0125 M 2 4 Solvent B = H O/CH CN 85/15 (v/v) Time (min. ) 0; 5 15; 25; %B 10; 10 83,5; 83,5; Lichrosorb column RP-18 (250X4 nm] / Column T 60°C Visualizer: UV (254 nm; Rt S.C.* about 12.9' Rt E.C.* about 9.5* * S.C. = starting compound E.C. = end compound TABLE 2 TABLE 2 (a) Isoserinol = 2, 3-dihydroxypropylamine (b) DBU = 1, 8-Diazabicyclo/5, 4, 0.7-7-undecene (c) TBAOH = Tetrabutylammoniu hydroxide (d) TAZA = 1, , 7, 10-Tetraazacyclododecane (e) BzTMAOH = Benzyltrimethylammonium hydroxide (f) TBAF = Tetrabutylammonium fluoride (g) HMPT = Hexa ethylphosphoryltriamide * s.c. ~ starting compound EXAMPLE 28 5-(N-2-hydroxyethyl-N-hydroxyacetyl-amino) -2, 4, 6-triiodo- bis-( 2, 3-dihydroxypropyl ) isophthalate . 7 g of 5-(N-2-hydroxyethylaminocarbonylmethoxy)-2, 4, 6-tri¬ iodo-bis-( 2, 3-dihydroxypropyl ) isophthalate (obtained according to the general procedure disclosed in EP-A-185.130 ) were dissolved in DMF at room temperature and added with an equimolar amount of CH ONa/CH OH 4 M. The reaction was monitored by T.L.C. and gave an approximate conversion percentage of 75%, after 32 hours, at room temperature. After evaporation of the solvent, the crude compound was worked according to the method described in Example 1, to give the desired product. 4.34 g of 5-(N-2-hydroxyethyl-N-hydroxyacetyl-ami- no) -2 , 4, 6-triiodo-bis-( 2, 3-dihydroxypropyl ) isophthalate were obtained. Yield: 62% Elemental analysis: Calc. % : C 26.7; H 2.7; I 47.09; N 1.7 Found % : C 26.2; H 3.0; I 46.95; N 2.01 By the same procedure, 5- (N-met.hyl-N-hydroxyacetyl- -amino) -2,4, 6-triiodo-bis-( 2, 3-dihydroxypropyl ) isophthalate was obtained from 5-(N-methylaminocarbonylmethoxy ) -2 , , 6- triiodo-bis-(2, 3-dihydroxypropyl ) isophtalate (obtained according to the general procedure illustrated in EP-A-185.130) . Yield: 70% m.p. : 104-110°C Elemental analysis Calc. % : C 26,21; H 2,59; I 48.87; N 1.80 Found % : C 25.10; H 2.64; I 47.40; N 2,02; H O 1.2 EXAMPLE 29 5-( -1, 3-dihydroxyisopropyl-N-hydroxyacety1-amino)-2, 4, 6- tribromo-bis-(1, 3-dihydroxyisopropyl)isophthalamide. 8.7 g of 5-( 1, 3-dihydroxyisopropylaminocarbonyl Jmethoxy- 2,4, 6-tribromo-bis-( 1, 3-dihydroxyisopropyl )isophthalamide (EP-A-185.130; Ex. 12) were suspended in 0.025 M borate buffer (pH = 9) and heated to 95°C, keeping constant pH. Rearrangement was monitored " by NMR (following the decrease of the signal of the aromatic C in the 5-position bound to the oxygen and the rise of the signal of the aromatic C in 5-position bound to the nitrogen atom, each of them respectively characterizing the starting and the final compound). The reaction was complete in about 18 hours, then the reaction mixture was treated according to the method described in Ex. 1, to give the desired compound. 4.26 g of 5-(N-l, 3-dihydroxyisopropyl-N-hydroxyacetyl-ami- no)-2, 4, 6-tribromo-bis-(1, 3-dihydroxyisopropyl)isophthala¬ mide were obtained. Yield: 49% Analysis: Calc. % : Br 34.43 Found % : Br 34.28 1 C NMR (Bruker AC200, provided with ASPECT 3000). Spectra were recorded in DMSO at room temperature. Chemical shifts of aromatic C in 5-position (referred to TMS) : C bound to -OR = 154.9 ppm (starting compound) C bound to - = 147 ppm (final compound) EXAMPLE 30 5-( N-methyl-N-hydroxyacetyl-amino)-2, 4, 6-triiodo-( (N-2, 3- dihydroxypropyl ) -( * -2-hydroxyethyl ) ) isophthalamide. 7,47 g of 5- (methylaminocarbonyl-methoxy)-2, 4, 6-triiodo- ( (N-2, 3-dihydroxypropyl )-(N'-2-hydroxyethyl ) ) isophthalamide (obtained according to the general procedure disclosed in EP-A-185.130 ) (0,01 mole) were suspended in 75 ml of water and heated to 95°C. 15 ml of NaOH 0,05 M were added and the reaction was stirred for 1 hour. Then, after cooling, the mixture was filtered and purified on Amberlite IR 120 (1,5 ml) and Amberlite IRA 400 (3 ml). The eluate was evaporated and the crude residue was crystallized from absolute ethanol. 5,1 g of 5-(methyl-N-hydroxyacetyl-amino) -2 , 4 , 6-tri¬ iodo( (N-2, 3-dihydroxypropyl )-(N' -2-hydroxyethyl ) ) isophtha¬ lamide were obtained. Yield: 68,3% mp: 259°C HPLC purity: 93% 1 ^ 13 IIRR;; HH aanndd CC NNMR spectra were in agreement with the proposed st ruct.ure EXAMPLE 31 1 , 3-bis- (N-3, 5-bis- ( 1, 3-dihydroxyisopropylaminocarbonyl ) - 2, 4 , 6-triiodo-phenyl )-N-hydroxyacetyl-amino) -2-hydroxy- propane. 2,5 g of 1 , 3-bis ( 3, 5-bis-( 1, 3-dihydroxyisopropylaminocar- bonyl ) -2, 4, 6-triiodo-phenoxy-acetylamino) -2-hydroxy-propa¬ ne (obtained according to the general procedure disclosed in EP-A-185.130) (0, 00158 mole) were suspended into 50 ml of water containing NaOH (0.0032 mole) and heated to 80°C. The reaction was monitored by H.P.L.C.; after 3.5 hours a conversion of 80% was obtained. After cooling and neutralization, the reaction mixture was worked according to the usual way of Example 1 and the final compound was purified by preparative HPLC. Preparative purification conditions: Column: HIBAR lichrosorb RP-8; 7 u (250 x 10) Eluent: A = H O B = H O/CH CN 1/1 v/v Gradient: (flow: 6 ml/min.); Visualizer = 254 nm T(min): 0.0; 8.0; 12.0; 28.0; 35.0; % B ; 10; 18; 18; 90; 90; 1,1 g of 1,3-bis-(N-( 3, 5-bis-( 1, 3-dihydroxyisopropylamino- carbonyl )-2, 4, 6-triiodo-phenyl)-N-hydroxyacetyl-amino)-2- hydroxy-propane were obtained. Yield: 44% m.p. 216-222°C 13 NNMMRR?; CC ((BBrruukkeerr AACC220000,, provided with ASPECT 3000) Spectra were recorded in DMSO at room temperature. 0 OH II A: Z-C-NH-CH_-CH-CH_ ■ NH-C-Z (starting compound) © Θ 2 ΘΘ ® wher (fina wher 2 A B | 42 24 © 43, 91 | 53 05 © 53, 10 | 69 30 © 59 42 | I 68 ,16 Θ 70 1 | 70 ,19 © 71 78 | 87 ,31 © 82 ,78 | 90 ,37 © 92 ,40 | 150 46 © 151 42 [ 156 63 © 145 31 | 166 54 ® 169 07 | 168 ,70 © 172 ,04 j Chemical shifts are expressed in ppm referred to TMS, HPLC; Rt = 9.65; 10.10 minutes (isomeric mixture) Lichrosorb RP-8 column; 5 u (250 x 4) Eluent: A = H 2 0 B = H O/CH CN 1/1 v/v Gradient: (flow: 1 ml/min) Visualizer: UV (254 nm) T (min.) = 0.0; 8.5; 12.0; 23.0; 35.0; %B = 10 ; 20; 20; 90; 90; EXAMPLE 32 1, 3-bis-(N-( 3, 5-bis-(N,N-bis-( 2-hydroxyethyl )aminocarbonyl) -2,4, 6-triiodo-phenyl )-N-hydroxyacetyl-amino)-2, 2-bis-(hy¬ droxymethyl)-propane A) 1, 3-bis-(chloroacetylamino)-2, 2-bis-(hydroxymethyl )-pro¬ pane 6.7 g of 2, 2-bis-(aminomethyl)-propane-l, 3-diol (obtained by a full conventional way; see: Beilstein 4 E III page 850; E IV page 1883) (0.05 mole) in 25 ml of methanol were dropped into a solution of 12 g of methyl-chloroacetate (0.11 mole) in 35 ml of methanol, while the temperature was kept between 0 and 5°C. Then the temperature was allowed to raise to 20-25°C and the mixture was stirred for 20 hours, until pH became neutral . Solvent was then evaporated and the residue was solidified under vacuum and in presence of P_0,_. 2 5 The crude residue was boiled three times with chloroform (3 x 40 ml) and the total organic layer was filtered and evaporated to give the desired product. 8,4 g of 1, 3-bis-(chloroacetylamino)-2, 2-bis-(hydroxy¬ methyl )-propane were obtained. Yield: 58.6% Elemental analysis: Calc. %: C 37.64; H 5.62; Cl 24.69 Found %: C 37.33; H 5.67; Cl 24.40 B) l,3-bis-(3,5-bis-(N,N-bis-( 2-hydroxyethyl )aminocarbo¬ nyl )-2, 4, 6-triiodo-phenoxy-acetylamino)-2, 2-bis-(hydro- xymethyl )-propane 2.3 g of 1, 3-bis-(chloroacetylamino)-2, 2-bis-(hydroxy¬ methyl)-propane (0.008 mole) and 2.4 g of sodium iodide (0.016 mole) were dissolved in 20 ml of water and heated to 40°C. To the mixture was dropwise added a solutio of 11.74 g of 5-hydroxy-2, 4, 6-triiodo-bis- (N, -bis-(2-hydroxyethyl) )-isophthalamide (obtained according to the general procedure disclosed in EP-A-185.130) (0.016 mole) in 32 ml of NaOH 0.5 M (0.016 mole), then the resulting solution was heated to 80°C for 24 hours. After cooling, the solution was diluted to 250 ml with water, percolated on Amberlite IRA 400 (60 ml) and Amberlite IR 120 (30 ml) and eluted with water. The aqueous layer was evaporated to give the desired product. 8.1 g of crude 1, 3-bis-( 3, 5-bis-(N,N-bis-(2-hydroxye¬ thyl) aminocarbonyl )-2, 4, 6-triiodo-phenoxy-acetylamino)- 2, 2-bis-(hydroxymethyl)-propane were obtained. Yield: 60.2% mp: 198°C Elemental Analysis: Calc. %: C 29.27: H 3.35; I 45.27; N 4.99 Found %: C 28.74; H 3.39; I 43.20; N 4.91 IR; H and C NMRspectra were in agreement with the proposed structure. C) 1, 3-bis-(N-3, 5-bis-(N,N-bis-( 2-hydroxyethyl)aminocarbo- nyl-2, 4, 6-triiodo-phenyl)-N-hydroxyacetyl-amino)-2, 2- bis-(hydroxymethyl)-propane 3.36 g of l,3-bis-(3,5-bis-(N,N-bis-(2-hydroxyethyl)- aminocarbonyl )-2, 4-6-triiodo-phenoxy- acetylamino)-2,2- bis-(hydroxymethyl )-propane (0.002 mole) were suspended into 65 ml of water containing NaOH (0.004 mole) and heated to 85°C. Percentage of conversion was monitored by HPLC. When a conversion of 85% was obtained, the mixture was cooled and worked according to the usual way of example 1 and the desired product was purified by preparative HPLC. Preparative purification condition: Column : HIBAR lichrosorb RP-8; 7 u (250 x 10) Eluent : A = H O B = H 0/CH CN 1/1 v/v Gradient : (flow: 6 ml/min); Visualizer: UV (245 nm) T (min): 0.0; 8.0; 12.0; 28.0; 35.0; % B : 10; 18; 18; 90; 90; 1 g of 1, 3-bis-(N-3, 5-bis-(N,N-bis-( 2-hydroxyethyl )amino¬ carbonyl )-2, 4, 6-triiodo-phenyl )-N-hydroxyacetyl-amino)-2,2- bis-(hydroxymethyl )-propane was obtained. Yield: 29.8% 1 13 IR; H and C NMR spectra were in agreement with the proposed structure. By the same procedure, 1, 3-bis-(chloroacetylamino) -2, 2- bis-(hydroxymethyl )-propane was reacted with 5-hydroxy-2, 4, 6-triiodo-( (N-2, 3-dihydroxypropyl )-(N 1 -2-hy¬ droxyethyl ))isophthalamide (obtained according to the general procedure disclosed in EP-A-185.130 ) to give the corresponding l,3-bis-(3-(2, 3-dihydroxypropylaminocarbo- nyl )-5-( 2-hydroxyethylaminocarbonyl ) -2, 4, 6-triiodo-phenoxy- acetylamino)-2, 2-bis-(hydroxymethyl)-propane, which in turn was rearranged to give the corresponding 1, 3-bis-(N-(3-(2, 3-dihydroxypropylaminocarbonyl)-5-(2-hydro¬ xyethylaminocarbonyl)-2,4, 6-triiodo-phenyl)-N-hydroxyacetyl -amino)-2, 2-bis-(hydroxymethyl)-propane. IR; H and c NMR spectra were in agreement with the proposed structure. By the same procedure, 1, 3-bis-(chloroacetylamino)-2, 2-bis- (hydroxymethyl)-propane was reacted with 5-hydroxy-2,4, 6- triiodo-( (N-1, 3-dihydroxyisopropyl)-(N l -2-hydroxyethyl) )- isophthalamide (obtained according to the general procedure disclosed in EP-A-185.130) to give the corresponding 1, 3-bis-( 3-(l, 3-dihydroxyisopropylaminocarbo- nyl)-5-( 2-hydroxyethylaminocarbonyl)-2, 4, 6-triiodo-phenoxy- acetylamino)-2, 2-bis-(hydroxymethyl)-propane, which in turn was rearranged to give the corresponding 1,3-bis-(N-( 3-(1, 3-dihydroxyisopropylaminocarbonyl)-5-(2- hydroxyethylaminocarbonyl)-2, 4, 6-triiodo-phenyl)-N-hydroxy- acetyl-amino)-2, 2-bis-(hydroxymethyl )-propane. IR; H and C NMR spectra were in agreement with the proposed structure. EXAMPLE 33 3, 5-bis-(N-2-hydroxyethyl-N-hydroxyacetyl-amino)-2, 4, 6-tri- iodo-( 1, 3-dihydroxyisopropyl)benzamide. 3,2 g of 3-(N-2-hydroxyethyl-N-hydroxyacyl-amino)-5-(N-2- hydroxyethylaminocarbonylmethoxy)-2, 4, 6-triiodo-( 1, 3-dihy¬ droxyisopropyl)benzamide were suspended in DMF and added with CH ONa/CH OH up to pH = 9. The reaction was kept at room temperature for 48 hours, then it was worked according to the usual procedure of example 1 to give the desired compound. 1,54 g of 3, 5-bis-(N-2-hydroxyethyl-N-hydroxyacetyl-ami- no)-2, 4, 6-triiodo-( 1, 3-dihydroxyisopropyl )benzamide were obtained. Yield: 48.1% Elemental analysis: Calc. % : C 26.76; H 2.97; I 47.21; N 5.20 Found % : C 26.32; H 2.89; I 47.31; N 5.20

Claims: AMENDED CLAIMS [received by the International Bureau on 10 November 1988 (10.11.88); original claim 18 amended; other claims unchanged (2 pages)] 17. 5-(N-l, 3-dihydroxyisopropyl-N-hydroxyacetyl-amino)- 2,4, 6-tribromo-bis-( 1, 3-dihydroxyisopropyl) isophthalamide ; 5-(N-1, 3-dihydroxyisopropy1-N-( 2-hydroxy-propionyl) -amino) 2, 4,6-triiodo-bis-( 1, 3-dihydroxyisopropyl)isophthalamide. 18. Novel <λ, υ ->-bis-(N-( 3, 5-bis-(hydroxyalkylamino- carbonyl) -2, 4, 6-triiodo or tribromo-phenyl )-N-hydroxy- alkanoyl-amino) -alkanes of formula XVI wherein: X = I, Br -Alkyl = a C -C alkyl group n = 1-3 R = H, CH 3 1 R" = H or a C -C hydroxyalkyl group carrying 1 to 3 hydroxy groups, which may be the same or different from -Alkyl(OH) n E = a C -C alkylene group, which may be interrupted by 0, S, SO, SO_ D = H, or C -C hydroxyalkyl group carrying 1 to 2 hydroxy groups with the proviso that in every compound the substituents - " - 19. 1,3-bis-(N-(3,5-bis-(N,N-bis-(2-hydroxyethyl)amino carbonyl)-2,4,6-triiodo-phenyl)-N-hydroxyacetyl-amino)-2, bis-(hydroxymethyl)-propane; 1, 3-bis(N-(3-(2 ,3-dihydroxypropylaminocarbonyl)-5-(2-hy¬ droxyethylaminocarbonyl)-2,4, 6-triiodo-phenyl)-N-hydroxy¬ acetyl-amino)-2,2-bis-(hydroxymethyl)-propaneι * l,3-bis(N-(3-(l, 3-dihydroxyisopropylaminocarbony1)-3-(2- hydroxyethylaminocarbonyl)-2,4, 6-triiodo-phenyl)-N-hydrox acetyl-amino)-2, 2-bis-(hydroxymethyl)-propane. 20. Novel 3,5-bis-(N-hydroxyalkyl-N-hydroxyacetyl-ami no)-2,4, 6-triiodo or tribromo-benzoic acid derivatives o general formula XVII CO-Y wherein : X, Y, R and R are defined according to formulae IX and X of claims 10 and 11. 21. 3,5-bis-( -2-hydroxyethyl-N-hydroxyacetyl-amino)- 2,4,6-triiodo-(1,3-dihydroxyisopropyl)benzamide. STATEME TUNDERARTICLE19 Substitution of the claim 18 has been requested in order to make the differences with the compounds of EP-A-0023992 clearer and to avoid any overlap with said document.

Inventors: FELDER ERNEST, FUMAGALLI LUCIANO, MUSU CARLO, UGGERI FULVIO, FELDER, ERNEST, FUMAGALLI, LUCIANO, MUSU, CARLO, UGGERI, FULVIO
Applicants: BRACCO IND CHIMICA SPA, BRACCO INDUSTRIA CHIMICA S.P.A.
Application year: 1988
Main classification: C07C103
IPC codes: A61K49, C07C231, C07C233, C07C235, C07C237