"4""-Deoxy-4""-arylglyoxamido- and aroylthioformamido derivatives of oleandomycin and its esters"

Derivatives of oleandomycin, its 11-monoalkanoyl, 2-monoalkanoyl and 11,2'-dialkanoyl esters having at the 4"-position an amino group substituted with --C(.dbd.O)--C(.dbd.O)--R.sub.3 or --C(.dbd.S)--C(.dbd.O)--R.sub.3 wherein R.sub.3 is alkyl having from one to four carbon atoms, phenyl, substituted phenyl, or a heterocyclyl group, their preparation and use as antibacterial agents is described.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a structurally unique group of macrolides and, 
more particularly, to derivatives of oleandomycin, its 11-mono-, 2'-mono- 
and 11,2'-dialkanoyl esters having at the 4"-position an amino group 
substituted with --C(.dbd.O)--C(.dbd.O)--R.sub.3 or 
--C(.dbd.S)--C(.dbd.O)--R.sub.3 wherein R.sub.3 is phenyl, substituted 
phenyl, or a heterocyclic group, and to methods for their preparation. The 
compounds are antibacterial agents. 
2. Description of the Prior Art 
Oleandomycin, a macrolide antibiotic produced by fermentation, was first 
described in U.S. Pat. No. 2,757,123. It has the formula, the absolute 
configuration of which is shown below: 
##STR1## 
It consists of three main structural features: the L-oleandrose moiety, 
the desosamine moiety and the oleandolide moiety. 
Derivatization of oleandomycin has focused primarily upon the formation of 
esters at one or more of three hydroxy groups located at the 2', 4" and 
11-positions. Mono- di and triacyl esters wherein the acyl moiety is 
derived from a lower aliphatic hydrocarbon monocarboxylic acid having from 
two to six carbon atoms are described in U.S. Pat. No. 3,022,219. 
Aminohydrin derivatives of oleandomycin are reported by Kastrons et al., 
Khim. Geterosikl Soedin (2), 168-71 (1974); C.A. 80, 145986n (1974). The 
compounds, for which no utility is reported, are prepared by treating 
oleandomycin with a dialkylamine or a heterocyclic amine in a sealed tube 
for twenty hours at 30.degree. C. The epoxide moiety at the 8-position is 
the site of reaction. 
SUMMARY OF THE INVENTION 
There has now been found a series of oleandomycin derivatives each of which 
exhibits valuable antibacterial activity in vitro and many of which 
exhibit in vivo activity by the parenteral and oral routes of 
administration, particularly against Gram-positive microorganisms. The 
compounds of this invention have formula II below wherein the wavy line 
connecting the substituted amino group at the 4"-position in generic to 
and embracive of both epimeric forms: 
##STR2## 
wherein R is selected from the group consisting of 
##STR3## 
wherein R.sub.3 is selected from the group consisting of a first subgroup 
consisting of 
##STR4## 
a second subgroup consisting of 
heterocyclyl, and 
a third subgroup consisting of 
alkyl having from one to four carbon atoms; 
wherein each of X and Y is selected from the group consisting of hydrogen, 
chloro, bromo, fluoro, alkyl having from one to four carbon atoms and 
alkoxy having from one to four carbon atoms; and Z is selected from the 
group consisting of X, dimethylamino, nitro and amino; 
heterocyclyl is selected from the group consisting of thienyl, furyl and 
pyridyl; 
and each of R.sub.1 and R.sub.2 is selected from the group consisting of 
hydrogen and alkanoyl having from two to three carbon atoms. 
Also included in the present invention are the pharmaceutically acceptable 
acid addition salts of compounds of formula II above. Representative of 
such salts, but not limited thereto, are the hydrochloride, hydrobromide, 
phosphate, sulfate, formate, acetate, propionate, butyrate, citrate, 
glycolate, lactate, tartrate, malate, maleate, fumarate, gluconate, 
stearate, mandelate, pamoate, benzoate, succinate, lactate, 
p-toluenesulfonate and aspartate. 
Favored because of their greater biological activity relative to that of 
other compounds described herein are compounds of formula II wherein 
R.sub.1 is alkanoyl or hydrogen, R.sub.2 is hydrogen, and R has the values 
shown below. 
______________________________________ 
R R.sub.3 X Y Z 
______________________________________ 
C(O)C(O)R.sub.3 C(S)C(O)R.sub.3 
##STR5## H H H Cl 
Z al- koxy 
C(S)C(O)R.sub.3 
heterocyclyl 
C(O)C(O)R.sub.3 
______________________________________ 
preferred compounds are those wherein R.sub.1 is acetyl or hydrogen; 
R.sub.2 is hydrogen and R has the values shown below: 
______________________________________ 
R R.sub.3 X Y Z 
______________________________________ 
C(O)C(O)R.sub.3 C(S)C(O)R.sub.3 
##STR6## H H H 
C(S)C(O)R.sub.3 
2-furyl 
C(O)C(O)R.sub.3 2-thienyl 
______________________________________ 
Compounds of formula II, including the epimeric forms thereof, and their 
pharmaceutically acceptable salts are effective antibacterial agents 
against Gram-positive microorganisms, e.g. Staphylococcus aureus and 
Streptococcus pyogenes, in vitro and many are active in vivo via the 
parenteral and oral routes of administration. Many of the compounds (and 
their salts) are also active against certain Gram-negative microorganisms, 
such as cocci, e.g. Pasteurella multocida and Neisseria sicca. 
DETAILED DESCRIPTION OF THE INVENTION 
The structurally unique oleandomycin derivatives of this invention of 
formula II are prepared by acylation of an amine of formula III: 
##STR7## 
wherein each of R.sub.1 and R.sub.2 is as previously defined, with 
appropriate acylating agents which afford the acyl moieties R.sub.3 
--C(.dbd.O)--C(.dbd.O)-- or R.sub.3 --C(.dbd.O)--C(.dbd.S)--. Suitable as 
acylating agents are mixed anhydrides, acid azides, carboxylic acids with 
carbodiimides or alkoxyacetylenes or with other reagents capable of 
achieving dehydrative coupling, "activated esters" such as thiol esters 
and phenolic esters, and acid halides. When the acyl moiety is of the 
formula R.sub.3 --C(--O)--C(.dbd.O)--, the preferred acylating agent is 
the carboxylic acid in the presence of a dehydrative coupling agent such 
as a carbodiimide, an alkoxyacetylene, N,N'-carbonyldiimidazole, 
N,N'-carbonyl-s-triazine, N-hydroxyphthalimide, N-hydroxysuccinimide and 
others known to those skilled in the art. Favored as coupling agents are 
the carbodiimides, many of which are readily available. 
Dicyclohexylcarbodiimide is a preferred coupling agent since a by-product 
of the reaction, dicyclohexylurea, is insoluble in a variety of solvents 
such as dioxane, tetrahydrofuran, chloroform, and diethyl ether and is 
readily removed from the reaction mixture, thus simplifying recovery and 
isolation of the desired product. 
Similarly, the use of ethylcarbodiimidomethylated polystyrene (Synthesis, 
No. 3, 208 [Abstract No. 4682] 1976) as coupling agent affords a 
convenient route to the desired acyl derivatives since no by-product 
acylurea is produced to complicate recovery of the desired acyl 
derivative. 
Also favored as coupling agents are various aliphatic carbodiimides bearing 
tertiary or quaternary amine substituents which render the corresponding 
by-product urea derivatives soluble in dilute acid or water and facilitate 
separation of the desired reaction product. Representative of such 
aliphatic carbodiimides are 
1-cyclohexyl-3-(4-diethylaminocyclohexyl)carbodiimide, 
1,3-di-(4-diethylaminocyclohexyl)carbodiimide, 
1-cyclohexyl-3-(.beta.-diethylaminoethyl)carbodiimide, 
1-cyclohexyl-3-(2-morpholinyl-(4)-ethyl)carbodiimide and the corresponding 
metho p-toluenesulfonate. 
The reaction is conducted in a reaction-inert solvent. When using an 
aliphatic carbodiimide bearing tertiary or quaternary amine substituents, 
dilute acid or water is generally used as solvent. Pure water can be used 
as solvent or, alternatively, a mixture of water and a water-miscible 
solvent can be used. In such instances, the water serves as co-solvent. 
Acetonitrile is a useful solvent when the coupling agent is an aliphatic 
carbodiimide having a quaternary amine substituent. When the coupling 
agent is a carbodiimide other than an aliphatic carbodiimide having 
tertiary or quaternary amine substituents, an organic solvent is required. 
Suitable solvents for such coupling agents are diethyl ether, benzene, 
dioxane, tetrahydrofuran, chloroform and methylene chloride. Alcohols can 
also be used as solvent but are less desirable because of side reactions 
with the carbodiimides. 
The dehydrative coupling reactions are conducted, in general, under mild 
conditions; for example, at temperatures ranging from about 20.degree. C. 
to about 50.degree. C. The molar proportion of dehydrative coupling agent 
to acylating agent to amine of formula III ranges from about 1:1:1 to 
about 1:1:1.5. 
When the acyl moiety has the formula R.sub.3 --C(.dbd.O)--C(.dbd.S)--, the 
favored acylating agent is the acid chloride having the formula R.sub.3 
--C(.dbd.O)--C(.dbd.S)--Cl because of the relative availability of such 
agents. A favored procedure comprises conducting the reaction in a 
reaction-inert solvent in the presence of an acid acceptor. An excess of 
the amine reactant of formula III can be used as the acid acceptor. 
Alternatively, a tertiary alkylamine, such as a trialkylamine having from 
3 to 12 carbon atoms, and preferably triethylamine, or other commonly used 
tertiary organic bases such as pyridine, N,N-dimethylaniline or 
N-methylmorpholine, can be used as the acid acceptor. The reaction is 
generally conducted in an inert atmosphere to avoid possible effects of 
atmospheric oxygen on the reactants. Alternatively, acylation of a 
compound of formula III with an acid halide is conducted under 
Schotten-Baumann conditions well known to those skilled in the art. 
The molar ratio of the acylthioformyl chloride reactant to amine reactant 
of formula III can vary widely, e.g. from about 1:1 to about 1:10. Molar 
ratios of less than 1:1 are avoided for economic reasons to insure maximum 
reaction of the amine reactant, normally the least readily available of 
the reactants. Ratios of greater than 1:10 are seldom used since they do 
not appear to improve the yield of final product. The use of an acid 
acceptor other than the amine reactant of formula III itself affords 
satisfactory yields of product with the use of from about 1:1 to about 1:3 
moles of amine reactant to the acylating agent. The reaction is 
essentially an acylation reaction. 
Suitable reaction-inert solvents (i.e., those which do not react to any 
appreciable extent with the reactants or products) are the dimethyl ether 
of ethylene glycol, tetrahydrofuran, n-dibutylether, diethylether, 
toluene, acetonitrile and methylene chloride. The principle criteria for 
the solvent are that it remain liquid at the relatively low temperatures 
at which the reaction is conducted and, of course, that it solubilize the 
reactants to an appreciable extent, if not completely. 
The reaction is carried out at temperatures from about -30.degree. C. to 
about 50.degree. C. This temperature range affords a satisfactory rate of 
reaction and eliminates or minimizes side reactions. 
Compounds of formula II wherein R.sub.3 is an amino substituted phenyl 
group are conveniently prepared by reduction of a corresponding compound 
wherein R.sub.3 is a nitro substituted phenyl group. The reduction is 
readily accomplished by catalytic hydrogenation over a noble metal 
catalyst such as palladium, especially palladium-on-carbon, in a 
reaction-inert solvent at ambient temperature. 
The required glyoxylic acid reactants having formula R.sub.3 
--C(.dbd.O)--C(.dbd.O)--OH are known compounds or, when not known, are 
readily obtainable by methods known to those skilled in the art. 
Representative procedures for producing glyoxylic acid or 
.alpha.-ketoacids having the above formula are discussed by Waters, in 
Chemical Reviews, 41, 585-598 (1947). 
The necessary acylthioformyl chloride reactants having formula R.sub.3 
--C(.dbd.O)--C(.dbd.S)--Cl are prepared according to the procedure 
described by Oka et al. in Tetrahedron Letters, 2783-2786 (1976), which 
comprises the reaction of an appropriate ketone having the formula R.sub.3 
--C(.dbd.O)--CH.sub.3 with 10-15 molar equivalents of thionyl chloride in 
the presence of 0.02 molar equivalent of pyridine at the reflux 
temperature. 
Where the starting amine of formula III is a mixture of epimers, the 
above-described acylation reactions produce a mixture of epimers 
(represented by a wavy line in formula II compounds) which can be 
separated, if desired. Column chromatography of a chloroform solution of 
the crude product on silica gel and elution with appropriate solvents, 
e.g. chloroform-3% methanol, offers a convenient method for separating the 
epimers. In the present description and illustrations, it is understood 
that although the compounds are listed as 4"-substituted amino 
derivatives, both epimers and mixtures thereof are included. Of course, if 
one begins with a given C.sub.4 " epimer of formula III, the corresponding 
C.sub.4 "-substituted compound of formula II is produced on acylation. 
Diester compounds of formula II; i.e., each of R.sub.1 and R.sub.2 is 
alkanoyl, can also be prepared by acylation of the corresponding 
11-monoalkanoyl (R.sub.1 =alkanoyl; R.sub.2 =H) compound by standard 
procedures known to those skilled in the art, and as exemplified herein. 
In this manner, preparation of diester compounds wherein the ester groups 
differ is readily achieved. 
Acid addition salts of the compounds of this invention are readily prepared 
by treating formula II compounds with at least an equimolar amount of the 
appropriate acid in a reaction-inert solvent for the formula II compound. 
When more than one basic group is present in a compound of formula II, the 
addition of sufficient acid to satisfy each basic group permits formation 
of poly acid addition salts. The acid addition salts are recovered by 
filtration if they are insoluble in the reaction-inert solvent, by 
precipitation by addition of a non-solvent for said salt, or by 
evaporation of the solvent. 
The 11-mono-alkanoyl-, 2'-monoalkanoyl- and 
11,2'-dialkanoyl-4"-deoxo-4"-amino-oleandomycin reactants (formula III) 
are prepared by reductive amination of the corresponding 
11-mono-alkanoyl-, 2'-monoalkanoyl- and 
11,2'-dialkanoyl-4"-deoxo-4"-oxo-oleandomycins using 
palladium-on-charcoal, hydrogen (from about 1 to about 500 p.s.i.) and 
ammonium acetate in a suitable solvent (CH.sub.3 OH, i-C.sub.3 H.sub.7 
OH). Alternatively, sodium cyanoborohydride can be used as reducing agent 
in place of palladium-on-charcoal and hydrogen. The de-esterified 
derivative is conveniently prepared by solvolysis of the corresponding 
2'-monoalkanoyl-4"-deoxo-4"-amino-oleandomycins. 
The stereochemistry of the starting materials leading to the antibacterial 
agents of the present invention is that of the natural material. Oxidation 
of the 4"-hydroxy groups of oleandomycin, erythromycins A and B, 
erythromycin A 11,12-carbonate, 6,9-hemiketal ester to a ketone and 
subsequent conversion of said ketone to the 4"-amines presents opportunity 
for the stereochemistry of the 4"-substituent to change from that of the 
natural product. Accordingly, when the 4"-oxo reactants are converted to 
amines, it is possible that epimeric amines are produced. In actual 
practice, it is observed that both epimeric amines are present in the 
final product in varying ratios depending upon the choice of synthetic 
method. If the isolated product consists predominantly of one of the 
epimers, said epimer can be purified by such methods as repeated 
crystallization from a suitable solvent to a constant melting point. The 
other epimer, the one present in smaller amount in the originally-isolated 
material, is the predominant product in the mother liquor. It can be 
recovered therefrom by methods known to those skilled in the art, such as, 
for example, by evaporation of the mother liquor and repeated 
recrystallization of the residue to a product of constant melting point or 
by chromatography. Although the mixture of epimeric amines can be 
separated by methods known to those skilled in the art, for practical 
reasons it is frequently advantageous to use said mixture as it is 
isolated from the reaction. Use of the epimeric mixture of 4"-amino 
reactants produces, of course, an epimeric mixture of the acylated 
products. The epimeric mixture thus produced can be separated by methods 
known to those skilled in the art. However, both epimers of a given 
compound exhibit the same type of activity and their separation, while 
desirable, is not always necessary. 
The novel oleandomycin derivatives described herein exhibit in vitro 
activity against a variety of Gram-positive microorganisms and against 
certain Gram-negative microorganisms such as those of spherical or 
ellipsoidal shape (cocci). Their activity is readily demonstrated by in 
vitro tests against various microorganisms in a brain-heart infusion 
medium by the usual two-fold serial dilution technique. Their in vitro 
activity renders them useful for topical application in the form of 
ointments, creams and the like; for sterilization purposes, e.g. sick-room 
utensils; and as industrial antimicrobials; for example, in water 
treatment, slime control, paint and wood preservation. 
For in vitro use, e.g. for topical application, it will often be convenient 
to compound the selected product with a pharmaceutically-acceptable 
carrier such as vegetable or mineral oil or an emollient cream. Similarly, 
they may be dissolved or dispersed in liquid carriers or solvents, such as 
water, alcohol, glycols or mixtures thereof or other 
pharmaceutically-acceptable inert media; that is, media which have no 
harmful effect on the active ingredient. For such purposes, it will 
generally be acceptable to employ concentrations of active ingredients of 
from about 0.01 percent to about 10 percent by weight based on total 
composition. 
Additionally, many compounds of this invention are active versus 
Gram-positive and certain Gram-negative microorganisms in vivo via the 
oral and/or parenteral routes of administration in animals, including man. 
Their in vivo activity is more limited as regards susceptible organisms 
and is determined by the usual procedure which comprises infecting mice of 
substantially uniform weight with the test organism and subsequently 
treating them orally or subcutaneously with the test compound. In 
practice, the mice, e.g. 10, are given an intraperitoneal inoculation of 
suitably diluted cultures containing approximately 1 to 10 times the 
LD.sub.100 (the lowest concentration of organisms required to produce 100% 
deaths). Control tests are simultaneously run in which mice receive 
inoculum of lower dilutions as a check on possible variation in virulence 
of the test organism. The test compound is administered 0.5 hour 
post-inoculation, and is repeated 4, 24 and 48 hours later. Surviving mice 
are held for four days after the last treatment and the number of 
survivors is noted. 
When used in vivo, these novel compounds can be administered orally or 
parenterally, e.g. by subcutaneous or intramuscular injection, at a dosage 
of from about 1 mg./kg. to about 200 mg./kg. of body weight per day. The 
favored dosage range is from about 5 mg./kg. to about 100 mg./kg. of body 
weight per day and the preferred range from about 5 mg./kg. to about 50 
mg./kg. of body weight per day. Vehicles suitable for parenteral injection 
may be either aqueous such as water, isotonic saline, isotonic dextrose, 
Ringer's solution, or nonaqueous such as fatty oils of vegetable origin 
(cotton seed, peanut oil, corn, sesame), dimethylsulfoxide and other 
non-aqueous vehicles which will not interfere with therapeutic efficiency 
of the preparation and are non-toxic in the volume or proportion used 
(glycerol, propylene glycol, sorbitol). Additionally, compositions 
suitable for extemporaneous preparation of solutions prior to 
administration may advantageously be made. Such compositions may include 
liquid diluents; for example, propylene glycol, diethyl carbonate, 
glycerol, sorbitol, etc.; buffering agents, hyaluronidase, local 
anesthetics and inorganic salts to afford desirable pharmacological 
properties. These compounds may also be combined with various 
pharmaceutically-acceptable inert carriers including solid diluents, 
aqueous vehicles, non-toxic organic solvents in the form of capsules, 
tablets, lozenges, troches, dry mixes, suspensions, solutions, elixirs and 
parenteral solutions or suspensions. In general, the compounds are used in 
various dosage forms at concentration levels ranging from about 0.5 
percent to about 90 percent by weight of the total composition.