NO138143B - ANALOGICAL PROCEDURE FOR THE PREPARATION OF NEW ESTERS OF ALFA-AMINOBENZYLPENICILLIN - Google Patents

Description

The invention relates to an analogue method of manufacture

of new esters of α-aminobenzylpenicillin with the formula

where the asterisk indicates the presence of an asymmetric carbon-

atom, and where A is a primary, secondary or tertiary alkyl group with 1-4 C atoms or a phenyl or

pyridyl group,

as well as salts of these esters with pharmaceutically acceptable acids.

Due to the asymmetric carbon atom in the side chain of the compound,

deis of formula I, these compounds exist in two epi-

more forms, and the invention includes the production of both epimeric forms as well as mixtures thereof. The form in which the compounds are obtained depends on which epimer starting materials

materials used as well as the connection methods. Mixtures,

of the epimeric forms can be separated by fractional crystalli-^

sation or in another known way.

It is known that the acid-resistant α-aminobenzylpenicillin is

a broad-spectrum antibiotic substance, which finds extensive use

share. When administered orally, α-aminobenzylpenicillin has imide-

however, the disadvantage is that it is only insufficiently absorbed in the organism, and it is therefore intended by the invention to produce

obtain new antibiotically active derivatives of α-aminobenzylpeni-

cillins, which, among other things, with regard to adequate absorption and distribution in the organism are better than α-aminobenzylpenicillin.

Acyloxymethyl esters of some penicillins are known, e.g.

from the Dutch patent application No. 6,405,981, where it is stated that such esters are literally not absorbed when administered orally. An exception is the acetoxymethyl ester of benzylpenicillin, which is absorbed to some extent and gives rise to low but prolonged blood concentrations. It is therefore surprising

that the compounds referred to here, when administered orally, produce extremely high concentrations of α-aminobenzylpenicillin in the blood and tissues due to efficient absorption in connection with rapid hydrolysis in the organism.

Table I below shows that the concentrations achieved in various organs, such as the liver, lungs, kidneys and spleen, are significantly higher after administration of the pivalyloxymethyl ester of D(-)-α-aminobenzylpenicillin than after administration of a corresponding dose of D(-)-α-aminobenzylpenicillin.

Table II below shows the difference in the serum concentrations of benzylpenicillin and D(-)-α-aminobenzylpenicillin respectively in dogs after a single oral dose of the acetoxymethyl ester of these two penicillins of 20 mg/kg body weight α-aminobenzylpenicillin.

Table IIa below indicates the serum concentrations of D(-)-α-aminobenzylpenicillin in subjects who have orally ingested 715 mg of the pivaloyloxymethyl ester of D(-)-α-aminobenzylpenicillin (corresponding to 500 mg of D(-)-α-aminobenzylpenicillin) during A, while the figures under B show the concentrations obtained after oral administration of 500 mg of D(-)-α-aminobenzylpenicillin (reference: Brit.Med.J., page 198 (vol. II, 1961). The values under A are average values from 10 people and under B average values from 7 people.

When the esters referred to here are exposed to the influence of enzymes found in the tissue fluids or enzymes produced by microorganisms, e.g. pathogenic microorganisms, they are readily hydrolysed to α-aminobenzylpenicillin. This hydrolysis is an important feature of the compounds according to the invention. It is believed that the first step consists in an enzymatic hydrolysis by means of non-specific esterases to form the corresponding hydroxymethyl esters of α-aminobenzylpenicillin, which then spontaneously decompose to α-aminobenzylpenicillin.

The present compounds of formula I are excellently tolerated

and are preferably administered orally, either as such or in the form of their salts, and they may be mixed with solid carriers or excipients or both. In such preparations, the ratio between the therapeutically active substance and carrier and auxiliary substances can vary between 1% and 95%. The preparations can either be processed into e.g. tablets, pills or dragees or filled medical containers such as capsules, or in the case of potions they can be filled in bottles". Pharmaceutically acceptable, organic or inorganic solid or liquid carriers suitable for oral or enteral administration or for local application by the preparation of the preparations. Gelatin, lactose, starch, magnesium stearate, talc, vegetable and animal fats and oils, plant gums and polyalkylene glycol as well as other known carriers for medicines are all suitable for the preparation of preparations of the compounds in question here. The preferred salt of the esters is the hydrochloride, but salts with other inorganic or organic acids, including antibiotically active acids, can be used, e.g. phosphates, acetates or salts with phenoxymethylpenicillin. Furthermore, the preparations may contain other pharmaceutically active components, which can conveniently be administered together with the esters referred to here during treatment of infectious diseases, e.g. other suitable antibiotic substances.

The remarkably high blood concentrations obtained after oral administration of a single dose of two of the compounds according to the invention, corresponding to 250 mg of α-aminobenzylpenicillin, are shown in Table III below, in which the figures indicate the serum concentrations in µg/ml, which are obtained by administration of the two esters in comparison with those obtained by administration of the a-aininobenzylpenicillin itself.

Further comparison experiments were also carried out.

1. Experiments were conducted to compare the oral absorption of ampicillin and penicillin G with their acetoxymethyl esters. For this purpose, a cross-over study was performed in conscious beagle dogs, in which the blood plasma level of antimicrobial agents such as ampicillin or penicillin G was determined at specified time points after oral administration of the antibiotics.

This study was a four-way cross-over study using a "latin square design" with 12 purebred beagle females, 6 males and 6 females. The dogs were starved for 18-20 hours before each experiment

and 1 week was allowed to pass between the experiments. Capsules containing the desired antibiotics were administered orally to the dogs

followed by 5 ml tap water. Blood samples were taken at 0, 0.25, 0.5, 1, 2 and 4 hours from the jugular vein using 5 ml heparinized Vacutainers. The blood samples were then quickly centrifuged and the plasma transferred to a sterile plastic tube for microbiological analysis. The microbiological measurements were carried out using standard techniques.

Commercially available capsules were used as the ampicillin, penicillin and penicillin G source (POLYCILLIN capsules containing 250 mg ampicillin equivalent per capsule; PENTIDS "400" capsules containing 250 mg potassium penicillin G). For determination of oral absorption of the acetoxymethyl esters, hard-gelatin capsules, dry-filled, were prepared, which contained acetoxymethyl-D-α-aminobenzylpenicillinate in an amount equivalent to 250 mg of anhydrous ampicillin and acetoxymethylbenzylpenicillinate in an amount equivalent to 250 mg of penicillin G.

The results of these experiments are indicated in the following table IV and in the accompanying graphic.

In this experiment, the acetoxymethyl ester of ampicillin produced the highest plasma levels of ampicillin with a peak at 1 hour. These levels are significantly higher than those obtained with ampicillin trihydrate, even after 2 hours. The acetoxymethyl ester of penicillin G was found to be less well absorbed than penicillin G at 15, 30 and 60 minutes, and in this respect was similar to penicillin G at 2 and 4 hours. 2. An experiment was also conducted to compare ampicillin and penicillin G blood plasma levels in dogs after giving these dogs ampicillin, penicillin G and certain esters of said compounds. The details of this experiment and the results obtained are given below.

In this experiment the ampicillin blood plasma levels obtained after giving various esters of ampicillin to anesthetized dogs were determined, as well as the penicillin blood plasma levels after giving the penicillin G ester. The experiment was conducted in the following ways

Fasted purebred beagle dogs were anesthetized with 35 mg

/kg i.v. PENTOBARBITAL. A midline abdominal incision was made and the jejunum was identified. A 15 cm segment of jejunum was then clamped using intestinal forceps, care being taken to avoid occlusion of the blood supply. Solutions or suspensions of the test compounds were administered to the isolated jejunum using a small syringe needle and a dose of 25 mg (ampicillin or penicillin equivalent) in 5 ml of saline. The jejunum segment was then carefully returned to the abdominal cavity and the incision site covered with saline-saturated sponges. Heating pads were used to keep the dogs warmed to 37-38°C. Blood samples were taken at 0, 0.25, 0.5, 1/2 and 4 hours from the femoral vein using 3 ml heparinized "Vacutainer" tubes. The blood samples were then quickly centrifuged and the plasma transferred to sterile plastic tubes for microbiological analysis. This analysis was performed using standard techniques.

The mean blood plasma levels (of two dogs per compound) in micrograms/ml at 1/4, 1/2, 1, 2 and 4 hours after administration of the compound are given in Table V below.

When preparing the compounds referred to here, certain considerations must be taken due to the presence of the cx-amino group in the side chain, and the hydrolysable ester group. The preparation takes place according to the invention either by: a) reacting an α-substituted benzylpenicillin with the general formula

where the asterisk has the above-mentioned meaning, and in which R means an amino group of the general formula Z-NH-, where Z stands for a conventional protecting group

or for hydrogen, or R means an azido group, nitro group or a bromine atom, and Y means a hydrogen atom* an alkali cation or a tertiary ammonium group, ;or a salt of a compound of formula II, with a compound of the general formula III;;where X means a chlorine or bromine atom, an acyloxy group with 1-16 C atoms, an alkylsulfonyloxy or arylsulfonyloxy group, and A has the above-mentioned . ;meaning, ;while forming a compound of the general formula IV ;;where R, A. and the asterisk have the above-mentioned meaning, ;after which any protective group present for the amino group is removed in the usual way or, if R means an azido or nitro group, hydrogenates this, or if R ; is a bromine atom, reacts this compound with hexamethylenetetramine, after which the thus formed compound of formula I is, if desired, transferred to a salt thereof with a pharmaceutically acceptable acid, ; or ;b ) that one reacts an acid halide, acid anhydride or mixed anhydride with an alkylcarboxylic acid, a carboxylic acid, an inorganic acid or a sulphonic acid, or the reaction product with a carbodiimide or an N,N'-carbonyldiimidazole of an acid with the general formula V ;;where H and the asterisk have the above-mentioned meaning, with a 6-aminopenicillanic acid ester of the general formula ;VI ;;where A has the above-mentioned meaning, and X' ;means a hydrogen atom or a t rialkylsilyl group with a maximum of 5 C atoms in the alkyl residue, to a compound of the general formula IV, after which this, if necessary, is transferred to a compound of the formula I or a salt thereof in the manner stated under method a)'. ;A summary characteristic of the substituent R is that it is selected from among groups which, after the above-mentioned reaction, can be converted into an amino group by methods which are sufficiently mild to avoid destruction of the molecule at the ester group or at the lactam ring. The substituent R has the formula Z-NH-, where Z is a benzyloxycarbonyl group, a parahalogen, paranitro or paramethoxybenzyloxycarbonyl group, a 3,3,3-trichloroethyloxycarbonyl group or an allyloxycarbonyl group, or Z can be a sulfur-containing radical, e.g. a tritylsulfonyl group or an arylsulfonyl group, e.g. an orthonitrophenyl group. Z can also be a triphenylmethyl (also called trityl), a tert.butoxycarbonyl group or a group obtained by reacting the free amino group with a 3-dicarbonyl compound, such as acetylacetone, an acetoacetic acid ester or benzoyacetone to form enamines or ;Schiffs "ske" bases. In general, it can be said that any Z group, which can be cleaved off by reduction, by mild acid hydrolysis or by other mild reactions known per se, will be suitable, as experiments have shown that the esters of formula I formed by the aforementioned reaction are stable under such conditions. The starting materials of formula II, where ;R is different from N^, are known intermediates in the synthesis of α-aminobenzylpenicillin. They exist in two epimeric forms. If the starting materials are prepared in form of the D- or L-epimer, one obtains the corresponding epimeric form of the compounds according to the invention. If, on the other hand, a mixture of the epimeric forms of the starting material is used, it is obtained a beanding. This mixture can be separated into the two isomers, e.g. by fractional crystallization. The methods for producing the starting materials with formula II are standard methods, which are used in peptide chemistry, and include e.g. the conversion of phenylacetic acid to R-substituted phenylacetic acid, where R has the above meaning, followed by a reaction between a reactive derivative of this intermediate and 6-aminopenicillanic acid, in which the amino group can be free or substituted, e.g. with a trimethylsilyl radical. Some of the starting materials of formula II can also be prepared from α-aminobenzylpenicillin or salts thereof. Some of the starting materials with formula III are known compounds, the preparation of which is described in the literature. Others are new, but can be prepared in the same way as those known using methods conventional for this type of compound. Among such methods may be mentioned the reaction of an acid halide with paraformaldehyde (e.g. as described in J.A.C.S. 43, 660 (1921)) or the halogenation of methyl esters (as e.g. described in Acta Chem. Scand. 20, 1273 (1966) and the references cited therein. The reaction of the compounds of formula II with the compounds of formula III can be carried out at or below room temperature or by gentle heating to the boiling point of the solvent used depending on the meaning of Y and X. Different organic solvents or mixtures thereof with water, e.g. acetone, dioxane, tetrahydrofuran, methylene chloride or dimethylformamide. The reaction products are crystalline or oily products, which can be used in the next step without further purification. By repeated precipitation, the oily products can be converted into crystalline or amorphous powders. ;The subsequent reaction step, in which the R group is converted into an amino group, can, depending on the the decipherment of R takes place by different methods, which are known from peptide syntheses. ;Catalytic hydrogenation is preferred, if R has the formula Z-NH-, and Z means benzyloxycarbonyl or related derivatives thereof, or if Z is trityl. The hydrogenation is preferably carried out at room temperature and either at atmospheric or slightly increased pressure in a solvent, which can be a non-reducible organic solvent or a mixture of such with water. The preferred catalysts are noble metal catalysts, e.g. palladium or platinum catalysts, or Raney nickel, but also other catalysts can be used. Electrolytic reduction can also be used in these cases. If Z is a (3,3,3-trichloroethyloxycarbonyl group, a reduction with Zn in acetic acid is preferred. A mild acid hydrolysis is preferred if Z is a sulfur-containing radical, an enamine, or a Schiff's base, e.g., a hydrolysis at a pH -value around 2 in a dilute solution of hydrogen chloride in aqueous acetone. A treatment with formic acid at room temperature is particularly well suited for the removal of Z if this is a tert.-butoxycarbonyl radical. Also known from the literature is the removal of an o-nitro- phenylsulfenyl radical by a nucleophilic attack.on the sulfur atom of the sulfenamide group, the best yield in this case being obtained with potassium or sodium iodide, sodium thiosulfate, sodium hydrogen sulfide, sodium dithionite or potassium thiocyanate. ;Other sulfenamide radicals are cleaved in the same way. If R is an azido or nitro group or a bromine atom, such groups can be converted into the free amino group in a known manner, the zido and nitro groups being hydrogenated catalytically with a noble metal catalysis ator or with Raney nickel or by an electrolytic reduction, and the bromine is converted by amination with hexamethylenetetramine. In embodiment b), as mentioned, a reactive derivative of the α-substituted phenylacetic acid of the formula V is reacted with an ester of 6-aminopenicillanic acid of the formula VI. In these formulas, R and A have the same meaning as before. X' is hydrogen or a trialkylsilyl group, where the alkyl group does not have more than 5 carbon atoms. The reaction can be carried out in one organic solvent or a mixture thereof with water, either at a low temperature or at a slightly increased temperature. Suitable solvents are methylene chloride, chloroform, ethyl acetate, acetone, dimethylformamide or diethylacetamide, ether, tetrahydrofuran, dioxane or similar inert solvents. The reaction products are isolated in a conventional way, e.g. by repeated precipitation or by removal of the solvent followed by a recrystallization of a solvent. The starting compounds with the formula V are known compounds, which can be prepared using standard methods known in peptide chemistry. The compounds of formula VI are new compounds which are interesting intermediates in the synthesis of compounds of formula I. They can be prepared by reacting 6-aminopenicillanic acid in the form of a salt, e.g. an alkali metal salt or the triethylammonium salt, with a halomethyl ester of the formula R 2 -CH 2 -OCC—A (VII), where R 2 is a halogen atom, preferably a chlorine or bromine atom, or a sulphonyloxy radical, e.g. the methanesulfonyloxy or toluenesulfonyloxy radical, and A is as previously defined. The 6-aminopenicillanic acid can be used as such, or the 6-amino group can be protected during the esterification process. Only protecting groups which can be easily removed without causing weakening of the lactam ring or the ester group are suitable in this case, e.g. triphenylmethyl or trimethylsilyl radicals. The reaction is carried out in an inert organic solvent, e.g. acetone, dimethylformamide or methylene chloride, and at or below room temperature or only slightly increased temperature. If the amino group is protected, the removal of the protecting group can be carried out in different ways, e.g. by hydrogenolysis or hydrolysis under neutral or acidic conditions, in which no attack occurs on the ^-lactam ring and the ester group. Reaction products with the formula VI (X'=H) are conveniently isolated in the form of their acid addition salts with e.g. p-toluenesulfonic acid or other inorganic or organic acids, such as sulfuric acid, phosphoric acid, hydrochloric acid, acetic acid, maleic acid, tartaric acid and other similar acids. The compounds of formula VI can also be prepared by esterification of the industrially available penicillins or preferably their salts with a compound of the aforementioned formula VII under similar conditions as already described, after which the side chain in the resulting penicillin esters is cleaved off to form the α-aminopenicillin ester of formula VI or a salt thereof. The cleavage of the amide bond can be carried out by a modification of the method described! Belgian patent no. 698,596, reacting the 6-acylaminopenicillanic acid ester with an acid halide in the presence of an acid binding agent, such as quinoline or pyridine. The preferred acid halide is, however, phosphorus pentachloride, because the reaction in this case can be carried out at a low temperature, which increases the stability of the intermediate product formed, which is presumably an iminohalide. The reaction can be carried out in various solvents, but the preferred solvents are chloroform and methylene chloride. ;The intermediate product is not isolated, but is treated with an excess of a primary alcohol to form an iminoether. The reaction temperature and reaction time depend on the alcohol used. In most cases, temperatures between -20°C and +20°C will be appropriate. The imino ether is not isolated either, but is subjected to an acid alcoholysis or hydrolysis, whereby the C=N bond is cleaved and the corresponding 6-aminopenicillanic acid ester of the formula VI is formed. It is surprising that the lactam ring and the acyloxymethyl ester group are sufficiently stable under these conditions. By . the commonly used methods, the esters of 6-aminopenicillanic acid can be isolated from the reaction mixtures as such or in the form of salts with inorganic or organic acids, e.g. ;in the form of hydrochloride or tosylate. The methods according to the invention and production of starting materials are illustrated by the following examples. ;EXAMPLE 1 ;A Acetoxymethyl-a-azido-benzylpenicillinate o ;A mixture of 2 g of potassium-a-azido-benzylpenicillinate, 0.5 g of potassium carbonate, 1.5 ml of acetoxymethyl bromide and 20 ml of "acetone" with a 2% water content is boiled under reflux for one hour. After cooling, the suspension is filtered and the filtrate evaporated in vacuo. The oily evaporation residue is washed repeatedly by decantation with petroleum ether to form the desired ester in the form of 2.5 g of a gummy substance, which does not crystallize. ;B Acetoxymethyl - g-aminobenzylpenicillinate, hydrochloride; To a solution of 2 g of acetoxymethyl-a-azidobenzylpenicillinate in 20 ml of ethyl acetate is added a solution of 980 mg of H^PO^ and 1 360 mg of KH2PO^ in 10 ml of water. 2 g of catalyst consisting of of 10% palladium on carbon, and the resulting mixture is shaken in a hydrogen atmosphere for 2 hours. The catalyst is filtered off and the phases are separated. The aqueous phase is washed with ether, neutralized to a pH of 7.5 with aqueous sodium bicarbonate and extracted several times with ethyl acetate. The combined extracts are washed with water, dried and evaporated in vacuo. The oily evaporation residue is suspended in 10 ml of ethanol, and 2.5 ml of 2~n ethanolic hydrochloric acid is added with stirring. The addition of ether to the resulting solution precipitates the hydrochloride of acetoxymethyl-α-aminobenzylpenicillinate, which is filtered off, washed with ether and dried. The product thus obtained is a colorless amorphous powder, which dissolves easily in water, methanol and ethanol, but is poorly soluble in ether and petroleum ether. The purity is determined iodometrically at 86%. The I.R. spectrum (KBr) contains strong bands at ;The free base is precipitated from an aqueous solution of the hydrochloride by the addition of aqueous sodium bicarbonate and is obtained in the form of a colorless amorphous powder. The N.M.R. spectrum (CDCl^) of the product shows characteristic signals at & = 7.32 (s), 5.76 (d), .5.53, 4.52, 4.43, 2.08. (s), 1.62 (s) and 1.50 (s), the IMS being used as. internal referral. EXAMPLE 2 D(-)-α-aminobenzylpenicillin-acetoxymethyl ester, hydrochloride 3.5 g of D(-)-α-aminobenzylpenicillin and 1.42 ml of triethylamine are mixed with 70 ml of acetone, which contains 1% water. 1 g of potassium bicarbonate and 1.75 ml of bromomethyl acetate are added to the resulting solution, after which the mixture is stirred at room temperature for 4 hours. After filtration, the filtrate is evaporated in vacuo to about 15 ml, 100 ml of ethyl acetate is added, and the resulting solution is washed with aqueous sodium bicarbonate followed by water. 30 ml of water is then added to the ethyl acetate solution and, with vigorous stirring, 1-1 hydrochloric acid is added dropwise, until the pH value of the aqueous phase is 2.5. The aqueous layer is filtered off and washed with ether. 150 ml of n-butanol are added, and the resulting mixture is evaporated in vacuo until all the water is removed. The resulting butanol solution of a total of 40 ml is poured into 500 ml of ether, whereby an amorphous precipitate separates. This is filtered off, washed with ether and dried, whereby the hydrochloride of the desired ester is obtained as a colorless product with - a purity of 83% (iodometrically determined). The I.R. spectrum (KBr): ;contains bands at -~ ;EXAMPLE 3 ;A Acetoxymethyl- g -(o-nitrophenylsulfenyiamjno)-benzylpenicillinate; 1.1 ml of acetoxymethyl bromide is added with stirring to a solution of 5.0 g of a-(o-nitrophenylsulfenylamino)-benzylpenicillin and 1.4 ml of triethylamine in 45 ml of methylene chloride The reaction mixture is stirred for 16 hours. It is then washed with 25 ml of water, 10 ml of aqueous sodium bicarbonate and 10 ml of water. The organic phase is dried and evaporated in vacuo to give a gum-like product, which is washed by decantation with petroleum ether. ;B Acetoxymethyl- g- aminobenzylpenicillinate, hydrocl orid ;To a solution of the crude acetoxymethyl-g<->(o-nitrophenylsulfonylamino)-benzylpenicillinate prepared according to A in 50 ml of ethyl acetate, a solution of 2.2 g of sodium thiosulphate in 50 ml of water is added under vigorous stirring. The aqueous phase is acidified with 4-n hydrochloric acid to a pH value of around 2, which is maintained during the reaction, if necessary by adding more acid. The reaction mixture is stirred for 15 minutes, after which the aqueous phase is separated, extracted with ether, neutralized with aqueous sodium bicarbonate to a pH value of about 7.5 and extracted twice with ethyl acetate. The organic phase is dried and evaporated in vacuo, whereby an oily evaporation residue is obtained which is dissolved in 25 ml of ethanol by the addition of 3 ml of 2-n alcoholic hydrochloric acid with stirring, after which it is precipitated by the addition of ether. The amorphous precipitate is filtered off and washed with ether. It consists of the aforementioned hydrochloride. ;EXAMPLE 4 ;A Acetoxymethyl-g-benzyloxycarbonylamino-benzylpenicillinate A mixture of 2.6 g of potassium-g<->benzyloxycarbonylamino-benzylpenicillinate, 0.5 g of potassium bicarbonate, 1.5 ml of acetoxymethyl bromide and 2 5 ml of acetone is refluxed in a hour. After cooling, the reaction mixture is filtered and the filtrate is evaporated in vacuo. The evaporation residue is dissolved in the ethyl acetate and extracted with water, aqueous sodium bicarbonate and water. ;B Acetoxymethyl-g-aminobenzylpenicillinate, hydrochloride To a solution of 0.98 g of orthophosphoric acid and 1.36 g of potassium dihydrogen phosphate in 25 ml of water, add 6 g of a catalyst consisting of 10% palladium on barium sulphate, and shake the suspension for one hour under hydrogen. A solution of the above gummy substance in 25 ml of ethyl acetate is added, and the resulting mixture is shaken in a hydrogen atmosphere for 2 hours at room temperature and atmospheric pressure. The catalyst is filtered off, and the aqueous phase is separated and washed with ether. The aqueous phase is neutralized to a pH value of around 7.5 with aqueous sodium bicarbonate and then extracted twice with ethyl acetate. The combined extracts are washed with water, dried and evaporated in vacuo. The resulting oily evaporation residue is then converted into the hydrochloride of acetoxymethyl-α-aminobenzylpenicillinate as described in example 3 B. ;EXAMPLE 5 ;A Acetoxymethyl-D-(-)-g-azidobenzylpenicillinate; 8.26 g potassium-D(-)-a -azidobenzylpenicillinate, 1.0 g of potassium bicarbonate and 4.1 ml of bromomethyl acetate are refluxed for one hour in a mixture of 50 ml of acetone and 1 ml of water. After cooling, the suspension is filtered, and the filtrate is evaporated in vacuo. The evaporation residue is washed repeatedly with petroleum ether to remove excess bromomethyl acetate. The oily evaporation residue is taken up in 50 ml of ethyl acetate, and the resulting solution is washed with aqueous sodium bicarbonate followed by water. After drying, the solvent is removed in vacuo and the desired compound is obtained as a rubber-like substance. ;B Acetoxymethyl- D(-)-g-aminobenzylpenicillinate, hydrochloride To a solution of 10.0 g of acetoxymethyl-D(-)-a-azidonebenzyl penicillinate in 150 ml of ethyl acetate, add 100 ml of water and 5 g of a catalyst consisting of 10% palladium on charcoal in a flask, which is equipped with an efficient stirrer, gas inlet and outlet ports, a combined glass and calomel electrode, and a burette, controlled by an automatic titrator. The system is flushed with nitrogen, after which a stream of hydrogen is bubbled through the suspension while stirring, a pH value of 3.0 being maintained by the addition of 1-n hydrochloric acid using the automatic titrator. When. consumption of the acid ceases, the flask is flushed with nitrogen until all the hydrogen is removed, and the catalyst is filtered off. The two phases in the filtrate are separated and the aqueous phase is washed with ether and freeze-dried. Thereby the desired compound is obtained as a colorless amorphous powder. The crystalline tosylate of acetoxymethyl-D(-)-α-aminobenzylpenicillinate is obtained by adding 0.5-n aqueous sodium p-toluenesulfonate to a 20% aqueous solution of the hydrochloride. The formed crystalline precipitate is separated, washed with water and dried to colorless crystals with a melting point of 166 - 167°C. ;Analysis ;Calculated for C26H31N3°9S2: C 52'55' H 5'26' N 7.09, S 10.80% Found: - "' C 52.80, H 5.42, N 6.88, S 10.64% ; EXAMPLE 6 ; Acetoxymethyl- a-aminobenzylpenicillinate ; To a stirring suspension of 340 mg of a-amino-phenylacetyl chloride, hydrochloride and 690 mg of acetoxymethyl-6-aminopenicillinate, p-toluenesulfonate in 8 ml of methylene chloride at 0°C add a solution of 0.50 ml of triethylamine in 2 ml of methylene chloride. After reaction for one hour at 0°C and 1/2 hour at room temperature, the reaction mixture is evaporated in vacuo and treated with 20 ml of ethyl acetate and 25 ml of water, which contains 0, 35 ml of 4-n hydrochloric acid. After shaking, the two phases are separated, the ethyl acetate is discarded, and the pH of the aqueous solution is adjusted to 7.5 by the addition of 3.5 ml of saturated sodium bicarbonate solution. The mixture is extracted with ethyl acetate, and the organic layer is dried over magnesium sulfate and evaporated, whereby the acetoxymethylpenicillin ester is obtained as a viscous oil. ;The IR spectrum of the substance (CHC1_) shows r band at 3,300 cm (NH), ;-1 -1 < " -1 ;1,875 cm (3-lactam), 1,760 cm (ester carbonyl) and 1,680 cm (amide). The identity of the compound is determined by conversion of the free base to the hydrochloride and comparison with an authentic sample. " ' ;I.R. spectrum (KBr) ;T.L.C. (thin layer chromatography): ;RF=0.51 (butanol-ethanol-H2O, 8+2+2) ;Rp=0.52 (butanol-acetic acid-H2o, 8+2+2 ) ;The starting material acetoxymethyl-6-aminopenicillinate, p-toluenesulfonate is prepared in the following ways: Acetoxymethyl-6-aminopenicillinate, p-toluenesulfonate Acetoxymethyl-6-tritylaminopenicillinate A solution of 11.5 g of 6-tritylaminopenicillanic acid in 65 ml of acetone is cooled to 0°C and the added 4.2 ml of triethylamine followed by 2.45 ml of acetoxymethyl bromide, after which the reaction mixture is kept under stirring at 0°C for 2 hours and then at room temperature for one hour. 3.5 g of triethylammonium bromide is precipitated, which is removed by filtration, and the evaporated filtrate is treated with 175 ml of ethyl acetate. After washing twice with cold 2% aqueous NaHCO^ and with ice water, the ethyl acetate layer is dried over MgSO^ and, by evaporation, gives the desired pure acetoxymethyl ester as an amorphous powder. ;Analysis ;Calculated for C3QH31<N>205S: C 67.77, H 5.87, N 5.27, S 6.04% Found: C 67.73, H 5.91, H 5.22, S 6.00* '

[α]^° : +109.8° (C=2; CHCl 3 ). Thin liquid chromatography on silica gel (Merck HF2^) shows a pure product.

Rp = 0.71 (butanol-ethanol-H2O, 8+2+2)

Rp -- 0.78 (butanol-acetic acid-H 2 O, 8+2+2).

B. Acetoxymethyl- 6-aminopenicillinate, p-toluenesulfonate

3.71 g of acetoxymethyl-6-tritylaminopenicillinate in 120 ml of acetone with 0.2% R^O is treated with. 1.21 g of anhydrous p-toluenesulfonic acid. After standing for 1 1/2 hours. at room temperature, 0.14 ml of water is added, and the p-toluenesulfonate is precipitated by the addition of 300 ml of petroleum ether Filtration and repeated washing with acetone-petroleum ether, ethyl acetate and ether leaves the crude salt.

After two recrystallizations from acetone-ether, a colorless crystalline product is obtained with a melting point of 132.5 - 134°C (decomposition).

Analysis

Calculated for C18H24N2°8S2: C 46'95' H 5'25' N 6'°8, S 13.92% Found: C 46.84, H 5.17, N 5.86, S 13.79%

[a]p<4> :+127.5° (C=1; ethanol)

Purity is further determined by thin-layer chromatography.

Rp = 0.51 (butanol-ethanol-H2O, 8+2+2)

Rp = 0.53 (butanol-CH 3 COOH-H 2 O, 8+2+2).

Iodometric testing using 6-aminopenicillanic acid as standard shows 99% purity.

Acetoxymethyl- 6-aminopenicillinate, p-toluenesulfonate

4.32 g of 6-aminopenicillanic acid dispersed in 140 ml of acetone is treated with stirring at 0°C with 6.3 ml of triethylamine. 3.2

ml of acetoxymethyl bromide is added dropwise, and the mixture is kept under stirring at room temperature for 4 hours. The formed triethylammonium bromide in an amount of 3.5 g is removed by filtration, and the filtrate is evaporated to dryness in vacuo, after which the evaporation residue is treated with 140 ml of ethyl acetate. and 110 ml of cold 2% bicarbonate solution. After shaking and separation, the ethyl acetate solution is shaken further with ice water and dried over magnesium sulfate. By evaporation, 5.2 g of substance is obtained. The crude ester dissolved in 200 ml of acetone is treated with 3.5 g of anhydrous p-toluenesulfonic acid, and the p-toluenesulfonate is precipitated by adding 750 ml of ether. It is filtered off and washed with ethyl acetate and ether.

The complete identity with the product obtained above is shown by comparison of melting points, I.R. spectra and I.L.C. data.

I.R. "(KBr) shows strong bands at

EXAMPLE 7

Acetoxymethyl-g-azido-benzylpenicillinate

580 ml of acetoxymethyl-6-aminopenicillanate, p-toluenesulfonate is added to a mixture of 50 ml of ethyl acetate and 50 ml of 2% aqueous sodium bicarbonate. 250 mg of <x-azido-a-phenylacetyl chloride dissolved in 5 ml of benzene are added to the mixture with vigorous stirring at 0°C. After 1/2 hour, the ethyl acetate layer is shaken with ice water, dried over magnesium sulfate and evaporated in vacuo to obtain the desired compound:

I.R. (KBr):

2 125 cm 1 (azido group)

1 780.cm<-1> (3-lactam)

1,765 cm (ester carbonyl)

1,690 cm"<1> (amide)

EXAMPLE 8

Acetoxymethyl-g-azidobenzylpenicillinate

600 mg of acetoxymethyl-6-aminopenicillanate, p-toluenesulfonate is shaken with a mixture of 35 ml of ethyl acetate and 17 ml of cold 2% sodium bicarbonate, after which the layers are separated, and the ethyl acetate solution is further shaken with 20 ml of ice water. It is then dried over magnesium sulfate and evaporated, whereby 360 mg of the free acetoxymethyl ester are obtained. This dissolves in 8

ml of methylene chloride and 255 mg of N,N'-dicyclohexyl-carbodiimide are added, after which the resulting solution

quickly while stirring is added to 220 mg of α-azidophenylacetic acid in 2.5 ml of N,N-dimethylformamide at 0°C. Stirring is continued for one hour at room temperature, and the mixture is filtered through diatomaceous earth. The filtrate is partially evaporated in vacuo and 25 ml of ethyl acetate is added. After shaking with 0.01-n hydrochloric acid and 2% sodium bicarbonate, the ethyl acetate layer is dried over magnesium sulfate. Removal of the solvent at room temperature gives a product which is identical to the product obtained by the method according to example 7.

EXAMPLE.9

A Propionyloxymethyl- D(-)- a- azidobenzylpenicillinate

This compound is prepared analogously to the pivaloyloxymethyl-D(-)-α-azidobenzylpenicillinate described in example 12 A,

using chloromethyl propionate as halogen methyl ester reagent.

B Propionyloxymethyl-D(-)-g-aminobenzylpenicillinate, hydrochloride The compound is prepared by catalytic hydrogenation of propionyloxymethyl-D(-)-a-azidobenzylpenicillinate in the same way as described in example 12 B. The desired compound

is reached as a colorless, amorphous powder and has a purity of 90% iodometrically determined.

I.R. (KBr): 1,780 (shoulder), 1,764 and 1,690 cm"<1>.

N.M.R. (D20) signals at & 7.94(s), 6.25 (d; J=l eps), 5.96 (s), 5.71 (s), 5.00 (s), 2.88 (m; J=7 eps), 1.85 (s) of 1.53

(t; J=7 eps), as IMS is used as an external reference.

[a]p° :+191° (c=1 in H 2 O) .

EXAMPLE 10

A Butyryloxymethyl-D(-)-a-azidobenzylpenicillinate This compound is prepared from D(-)-a-azidobenzylpenicillin's potassium salt and chloromethylbutyrate in a similar manner to the preparation of pivaloyloxymethyl-D(-)-a-azidobenzylpenicillinate described in example 12 A.

B Butyryloxymethyl-D(-)-g-aminobenzylpenicillinate, hydrochloride The compound is prepared by catalytic hydrogenation of butyryloxymethyl-D(-)-a-azidobenzylpenicillinate using the method described in example J 2 B and is obtained as a colorless amorphous powder.

The purity of the compound is determined iodometrically as 90.2%.

I.R. (KBr): Bands at 1,780-1,775 (shoulder), 1,763 of 1,688 cm"<1>. N.M.R. (D20): Signals at S = 7.94 (s), 6.25 (d; J= l.5 eps), 5.97 (s), 5.73 (s), 5.00 (s), 2.82 (t; J=7.5 eps), 2.04 (m; J= 7.5 eps), 1.83 (s) of 1.34 (t; J=7.5 eps), TMS being used as an external reference.

[a]p° : +197° (c=1 in H 2 O).

EXAMPLE 11

A Isobutyryloxymethyl-D(-)-g-azidobenzylpenicillinate The compound is prepared from potassium D(-)-a-azidobenzylpenicillinate and chloromethyl isobutyrate in the same way as the pivaloyloxymethyl-D(-)-a-azidonebenzylpenicillinate described in example 12 A.

B Isobutyryloxymethyl- D('->- a-aminobenzylpenicillinate, hydrochloride The compound is obtained as a colorless amorphous powder by catalytic hydrogenation of isobutyryloxymethyl-D(-)-g<->azidobenzylpenicillinate using the method described in Example 12B. The compound has a purity of 92.6% determined iodometrically.

I.R. (KBr): Bands at 1,780 (shoulder), 1,760-1,755, and 1,690 cm"<1>. N.M.R. (D2C): Signals at S = 7.94 (s), 6.27 (d; J =l.5 eps), 5.98 (s), 5.71 (s), 5.01 (s), 3.09 (m; J=7 eps), 1.82 (s), 1.57

(d; J=7 eps), TMS being used as an external reference.

[<g>]^° : +196° (c=1 in H^O) .

EXAMPLE 12

A Pivaloyloxymethyl- D(-)- a- azidobenzylpenicillinate

To a suspension of 4.14 g of potassium D(-)-α-azidobenzylpenicillinate and 1.5 g of potassium bicarbonate in 100 ml of acetone and 2 ml of 10% aqueous sodium hydroxide, 2.7 ml of chloromethyl pivalate are added, and the mixture is boiled under reflux in 2 hours. After cooling, filter

the resulting suspension, and the filtrate evaporated to dryness in vacuo. The evaporation residue is washed repeatedly by decantation with petroleum ether to remove unreacted chloromethylpivalate. The oily residue is taken up in 100 ml of ethyl acetate, and the resulting solution is washed with aqueous sodium bicarbonate and water, dried and evaporated in vacuo to give the desired compound as a yellowish gum, which crystallizes from ether. Melting point 114 - 115°C.

[o]J°: +42°C (c=1, CHC13)

The I.R. spectrum (KBr) contains strong bands at 1230, 1786, 1760, 1700, 1530, 1225, 1110 and 973 cm"<1>.

B Pivaloyloxymethyl-D(-)-g-aminobenzylpenicillinate, hydrochloride To a solution of the pivaloyloxymethyl-D(-)-g<->azidobenzylpenicillinate prepared according to the above description in 75 ml of ethyl acetate is added 75 ml of a 0.2- n phosphate buffer (pH=2.2) and 4 g of a catalyst consisting of 10% palladium now carbon. The mixture is shaken in a hydrogen atmosphere for 2 hours at room temperature. The catalyst is filtered off/it is washed with 25 ml of ethyl acetate and 25 ml of phosphate buffer, after which the phases of the filtrate are separated. The aqueous phase is washed with ether, neutralized to a pH value of 6.5 - 7.0 with aqueous sodium bicarbonate and extracted with 2 x 75 ml of ethyl acetate. 75 ml of water is added to the combined extracts, and the pH is adjusted to 2.5 with 1-1 hydrochloric acid. The aqueous layer is separated, the organic phase is extracted with 25 ml of water, and the combined aqueous extracts are washed with ether and oven-dried. The desired compound is obtained in the form of a colorless amorphous powder, which is soluble in water, methanol and ethanol.

The I.R. spectrum (KBr) contains bands at 1,780 (shoulder), 1~765-

1,755 and 1,690 cm'<1>.

The NMR spectrum (D 2 O ) shows signals at & = 7.94 (s), 6.29 (m), 5.94 (s), 5.78 (s), 4.96 (s), 1.79 (s) and 1.55 (s), as it"

TMS is used as an external reference.

[a]^<0>: +195° (c=1 in H 2 O).

The purity of the compound is iodometrically determined to be 91%. A crystalline hydrochloride is obtained from isopropanol and has a melting point of 155-156°C (decomposition).

[a]p°: +196° (c=1 in H 2 O).

EXAMPLE 13

Pivaloyloxymethyl- 6-aminopenicillinate, p-toluenesulfonate

To a stirring solution of 5.6 g of triethylammonium-6-tritylaminopenicillinate in 125 ml of acetone at 0°C is added 1.08 ml of triethylamine and then 1.6 ml of chloromethylpivalate in 2.3

g triethylammonium iodide. Stirring is continued at 0°C for 1/2 hour and at room temperature for 20 hours. The precipitate of triethylammonium chloride is filtered off, and the evaporated filtrate is treated with 75 ml of ethyl acetate. After shaking with 1% cold aqueous NaHCO^ and with ice water, the ethyl acetate layer is separated, dried over MgSO^ and evaporated in vacuo, whereby the pivaloyloxymethyl ester of 6-tritylaminopenicillin acid is obtained as an amorphous powder. To the crude ester dissolved in 40 ml of ethyl acetate is added a solution of 1.90 g of p-toluenesulfonic acid hydrate in 20

ml of ethyl acetate at 0°C. After further stirring for 2 hours at room temperature, the desired tosylate is filtered off and washed with ethyl acetate and ether. Recrystallization from acetone-ether gives the pure crystalline compound with melting point 139 - 139°C (decomposition).

Analysis

Calculated for c2iH30N2°8<S>2<:> C 50'18' H 6'01' N, 5.57, S 12.76% Found: C 50.46, H 6.15, N 5.36, S 12.57%

[a]p<4> : +131° (c=1 in ethanol).

I.R. (KBr) shows strong bands at 1 795, 1 768, 1 750, 1 545,

1485, 1465, 1375, 1365, 1210, 1160, 1115, 1030, 1010, 980, 815 and 680 cm<-1>.

Iodometric testing using 6-aminopenicillic acid as a reference shows 99% purity. The purity of the compound is further shown by thin-layer chromatography on silica gel (Merck, HF254).

Rp = 0.66 (n-butanol-ethanol-H 2 O, 4+1+1).

Rp = 0.12 (cyclohexane-ethyl acetate, 1+1).

EXAMPLE 14

Pivaloyloxymethy. l- 6-aminopenicillanate, p-toluenesulfonate 4.32g of 6-aminopenicillanic acid dispersed in 140 ml of acetone at

0°C is treated with 6.4 ml of triethylamine. While stirring at 0°C, 5.9 ml of chloromethyl pivalate and 4.6 g of triethylammonium iodide are added, and the stirred mixture is allowed to stand for 20 hours at room temperature. Triethylammonium chloride in an amount of 2.9 g is removed by filtration, and the evaporated filtrate is worked up as described in example 13, whereby the crude pivaloyloxymethyl ester is obtained. This is taken up in 45 ml of ethyl acetate. Treatment with 3.4 g of anhydrous p-toluenesulfonic acid in 50 ml of ethyl acetate results in immediate precipitation of the crystalline tosylate, which is filtered off and washed with ethyl acetate and ether to give a pure unsolvated substance, which in every respect proves to be identical to the analytical pure compound in example 13.

EXAMPLE 15

Pivaloyloxymethyl- 6-aminopenicillanate, p-toluenesulfonate

A dispersion of 2.16 g of 6-aminopenicillanic acid in 70 ml of acetone

at 0°C is treated with 3.2 ml of triethylamine and then 3.92 g of bromomethyl pivalate (boiling point 50 - 51°C at 10 mm Hg), which is prepared from pivaloyl bromide and paraformaldehyde by a procedure analogous to that in J.A.C.S. 89, 5442 (1967) described the preparation of chloromethyl pivalate.

After stirring for 20 hours at room temperature, 1.63 g of triethylammonium bromide is filtered off, and the evaporated filtrate is worked up as described in example 13. The crude pivaloyloxymethyl ester is dissolved in 45 ml of ethyl acetate and crystallization of the pure tosylate takes place by adding 1.72 g of anhydrous p <->toluenesulfonic acid in 25 ml of ethyl acetate. The product isolated by filtration and washing with ethyl acetate and ether shows complete identity

with the product according to example 13.

EXAMPLE 16

Pivaloyloxymethyl- 6-aminopenicillanate, p-toluenesulfonate

To 2.16 g of 6-aminopenicillanic acid dispersed in 60 ml of acetone at 0°C is added 1.8 ml of triethylamine followed by 3.2 g of a solution of pivaloyloxymethyl-p-toluenesulfonate in 10 ml of acetone. The mixture is stirred for 1/2 hour at 0°C for 20 hours at room temperature. The resulting clear solution is evaporated in vacuo, and the evaporation residue is worked up as described in example 13. To the crude ester in 75 ml of ethyl acetate

•add 1.7 g of anhydrous p-toluenesulfonic acid to 25 ml of ethyl acetate.

The precipitated crystalline salt is after filtration and washing

with ethyl acetate identical to the compound prepared according to example 13.

The starting material, pivaloyloxymethyl-p-toluenesulfonate, is prepared by reacting the silver salt of p-toluenesulfonic acid with chloromethylpivalate in dry acetonitrile for 4 days at room temperature and has a melting point of 44 - 44.5°C.

Analysis

Calculated for C, _,H, aOnS: C 54 .53, H 6.33, S 11.20%

iJ lo b

Found: C 54.73, H 6.31, S 11.09%.

EXAMPLE 17

Pivaloyloxymethyl- 6-aminopenicillanate, p-toluenesulfonate

To a dispersion of 2.16 g of 6-aminopenicillanic acid and 1.0 g of potassium bicarbonate in 70 ml of acetone, 1.56 ml of chloromethyl pivalate and 280 mg of potassium iodide are added. The mixture is stirred and boiled under reflux for 5 hours. Solid material is filtered off, and the acetone solution is evaporated in vacuo. The evaporation residue is triturated with 80 ml of ethyl acetate and, after filtration, the cooled ethyl acetate solution is treated with 1.72 g of anhydrous p-toluenesulfonic acid in 40 ml of ethyl acetate. The precipitated tosylate is collected on a filter

and washed with ethyl acetate and ether. Melting point, I.R. spectrum and T.L.C. data for the colorless crystalline product show its

identity with the same compound obtained according to the previous examples.

EXAMPLE 18

Pivaloyloxymethyl- 6-aminopenicillanate, hydrochloride

To a solution of 2.1 g of PCl^ in 20 ml of dry alcohol-free chloroform, add 2.6 ml of dry quinoline while stirring. The resulting suspension is cooled to -30°C and 4.0 g of pivaloyloxymethylbenzylpenicillinate is added. After stirring for 30 minutes at -5°C to -10°C, the solution is cooled to -30°C and 6.7 ml of dry n-propanol is added in one portion. The temperature rises to -10°C to -15°C. The reaction temperature is increased to 0°C within 15 minutes and maintained at this temperature for 30 minutes, after which the solution is added to an ice-cold mixture of 25 ml of water and 40 ml of hexane with stirring. The aqueous phase is separated, and the organic phase is extracted three times with 25 ml of ice-cold 1-n HCl. The combined aqueous phases are stirred at 0°C with 90 ml of ethyl acetate, the pH value being adjusted to 7.5 with NaHCO^• The organic phase is separated, dried and evaporated in vacuo, giving an oil, which is dissolved in 50 ml isopropanol at 0°C. By adding 1.75 ml of an 8-n dry solution of hydrogen chloride in isopropanol with stirring, the desired hydrochloride is precipitated. It is filtered off and washed with isopropanol and ether, thereby obtaining a pure product with a melting point of 156 - 160°C (Decomposition).

Analysis

Calculated for C14H23C1N205S: C 45.84, H 6.32, Cl 9.66, N 7.63,

S 8.74%

Found: C 45.60, H 6.39, Cl 9.76, N 7.54,

S 8.83%

[<x]J° +183° (c=1; 0.1-n HCl) .

I.R. spectrum (KBr) shows characteristic strong carbonyl bands at 1790, 1767 and 1756 cm"<1>.

The starting material can be produced in the following way:

Pivaloyloxymethyl benzylpenicillinate

To a suspension of 19.0 g of potassium benzylpenicillinate in 200 ml of acetone is added 8.3 ml of chloromethyl pivalate followed by a solution of 1.25 g of sodium iodide in 5 ml of water. The mixture is boiled under reflux for 5 hours. After cooling, the potassium chloride is removed by filtration. By adding water to the filtrate, the desired compound is obtained as a colorless crystalline product with a melting point of 114 - 115°C.

Analysis Calculated for C22H2gN206S: C 58.91, H 6.30, N 6.24%

Found: C 58.82, H 6.33, N 6.28%

[α]2^ : +236° (c=1 in methanol).

Thin layer chromatography on silica gel (Merck HF2^^) showed a

pure product.

Rp = 0.45 (cyclohexane-ethyl acetate, 1+1)

Rp = 0.86 (butanol-ethanol-H 2 O, 4+1+1).

EXAMPLE 19

Pivaloyloxymethyl- 6-aminopenicillanate

24.0 g of pivaloyloxymethyl-6-aminopenicillanate, p-toluenesulfonate suspended in 1.1 1 ethyl acetate are treated with 750 ml of 2% aqueous sodium bicarbonate with vigorous stirring. The phases separate,

and the ethyl acetate solution is shaken thoroughly with 600 ml of ice water,

to which 25 ml of 2% sodium bicarbonate has been added.

The ethyl acetate layer is dried over anhydrous magnesium sulfate, filtered and evaporated in vacuo. The evaporation residue is treated with 200 ml of petroleum ether (boiling point less than 50°C). Upon stirring for 2 1/2 hours, the analytically pure ester with a melting point of 60 - 65°C crystallizes out.

Analysis

Calculated for C14H22<N>2<0>5S: C 50.90, H 6.71, N 8.48, S 9.71% Found: C 51.15, H 6.77, N 8.36, S 9.63%

[a]20: +194° (c=1; C^OH)

take] 20. +184° (c=1; CHCl3)

The I.R. spectrum (KBr) shows characteristic bands at 3,400, 1,780 and 1,750 cm 1 .

EXAMPLE 2 0

Pivaloyloxymethyl-D(-)-α-aminobenzylpenicillinate, hydrochloride 7.4 g of pivaloyloxymethyl-6-aminopenicillianate, hydrochloride are suspended with vigorous stirring in 100 ml of dry ethanol-free chloroform at 0°C. 4.3 g of sodium bicarbonate are added and then 5.0 g of D(-)-α-phenylglycyl chloride, hydrochloride prepared according to J.Org.Chem 31, 897 (1966).

It is stirred for 3 hours at 0°C, after which the reaction mixture is filtered through diatomaceous earth, and the clear filtrate is evaporated in vacuo. The colorless evaporation residue is crystallized from isopropanol-ether, filtered off and washed with isopropanol and ether, whereby the desired compound is obtained in a very pure state and shows complete identity with the hydrochloride of D(-)-α-aminobenzylpenicillin-pivaloyloxymethyl ester obtained by the i example 12 B specified procedure.

EXAMPLE 21

Pivaloyloxymethyl- D(-)- a-aminobenzyl penicillinate, hydrochloride To a solution of 155.2 g of potassium N-[1-methyl-2-carbethoxyvinyl] D-(-)-a-amino-a-phenylacetate (0.5 mol of the hemihydrate) in 2 1 ethyl acetate, 2.5 ml of N-methylmorpholine and 70 ml of isobutyl chloroformate are added at -15°C with stirring. Potassium chloride is immediately separated, and the mixture is kept at -15°C for 6 minutes. An ice-cold solution of pivaloyloxymethyl-6-aminopenicillanate in 1 1 of ethyl acetate - prepared from 2 51.3 g of the crystalline p-toluenesulfonate of the compound - is then added with stirring, keeping the temperature between -14°C and -12°C during the acylation. After stirring for a further 10 minutes at a low temperature, the cooling bath is removed, and the mixture is stirred at room temperature for 30 minutes. It is then extracted with 500 ml of 0.5-n aqueous sodium bicarbonate and washed with 2 x 250 ml of water. The organic phase is dried and the solvent is removed

vacuum. The yellow oily residue thus obtained is dissolved in acetone, to which is added 0.9 1 of water, and 4-n hydrochloric acid is added dropwise to the mixture with vigorous stirring.

During the hydrolysis, a pH value of 2.5 is maintained in the mixture with the help of an automatic titrator. The reaction is finished when the consumption of hydrochloric acid ceases after the addition of 100 -

110 ml (80 - 88% of the theoretical amount). The acetone is removed

from the mixture by evaporation in vacuo (bath temperature around 35°C), and the remaining aqueous phase is extracted several times with ethyl acetate. After separation of the aqueous layer, the combined ethyl acetate extracts are diluted with 800 ml of petroleum ether and extracted with 200 ml of water at a pH value of 3. To the combined aqueous extracts, about 1200 ml, 240 g of sodium chloride are added, and the mixture is shaken vigorously , after which a yellowish organic layer separates. The aqueous phase is further extracted with 200 ml of ethyl acetate and the combined organic phases are dried over magnesium sulfate and filtered, after which 800 ml of isopropanol is added to the filtrate.-After concentrating the solution under reduced pressure to about half the volume (bath temperature about 35°C), a further 800 ml isopropanol is added, and the mixture is concentrated in vacuo to 600 - 800 ml. The mixture is stirred for one hour at room temperature and allowed to stand for 16 hours in the refrigerator, whereby crystalline material separates. This is filtered off, washed with 100 ml of ice-cold isopropanol and 2 x 100 ml of ether and dried at room temperature, whereby the desired compound is obtained as colorless crystals with melting point 155 - 156°C (decomposition), [a]+19«° (c= l in H2<0>).

A Benzoyloxymethyl- D(-)- a- azidobenzylpenicillinate

To a suspension of 4.14 g of potassium D(-)-α-azidobenzylpenicillinate in a mixture of 100 ml of acetone and 2 ml of 10% aqueous sodium iodide, 2.5 g of chloromethyl benzoate are added, and the mixture is boiled under reflux for 6 hours. After cooling, the suspension is filtered, and the filtrate is evaporated to dryness in vacuo. The evaporation residue is washed with a light petroleum fraction to remove excess chloromethyl benzoate, and then dissolved in 50 ml of ethyl acetate. The solution is washed with aqueous sodium bicarbonate followed by water, dried and evaporated in vacuo, whereby the desired compound is obtained as a gum-like substance.

B Benzoyloxymethyl-D(-)-a-aminobenzylpenicillinate, hydrochloride To a solution of 5.0 g of benzoyloxymethyl-D(-)-a-azidobenzylpenicillinate in 75 ml of ethyl acetate, add 50 ml of water and 3 g of a catalyst consisting of 10% palladium on coal in a flask, which is equipped with an efficient stirrer, necks for supply

seal and outlet of gas, a combined glass-calomel electrode and a burette, which is operated by an automatic titrator. The system is flushed with nitrogen, after which a stream of hydrogen is bubbled through the suspension while stirring, with a pH value of 3.0 being maintained in the aqueous phase by the addition of 1-n hydrochloric acid through the automatic titrator. When the acid consumption ceases, the flask is flushed with nitrogen until all hydrogen is removed, and the catalyst is filtered off. The two phases in the filtrate are separated, and the aqueous phase is washed with ether and freeze-dried. Thereby the desired compound is obtained as a colorless loose powder which is easily soluble in water.

[α]^°: +175° (c=1, H 2 O).

The N.M.R. spectrum (D20) shows signals at δ = 7.93 (m) (10 H), 6.29 (m) (2 H), approx. 5.84 (m) (3 H), 4.90 (s) (1 H), 1.66 (3 H) and 1.54 (3 H), T.MS being used as an external reference.

The purity of the compound is determined iodometrically as 92%.

EXAMPLE 23

Nicotinoyloxymethyl-D(-)-g-aminobenzylpenicillanate, hydrochloride By using the method indicated in Example 22 A and B, replacing the chloromethylbenzoate with the chloromethyl ester of nicotinic acid, the title compound is obtained, which was isolated as a hydrochloride, which showed the following nmr -data:

(instrument variant A60A, 10% weight/volume in CD30D, TMS):

4= 9.16, 8.82, 843 and 7.60 (4m, 4H, pyridyl-CH), 7.49 (s, 5H, phenyl-CH), 6.14 and 6.08 (dd, J =6, 2H, 0CH2O), 5.61 (d, J=4, 1H, CH-6), 5.53 (d, J=4, 1H, CH-5), 5.16 (s, C^ CH) , 4.48 (s, 1H, CH-3), 1.46 and 1.39 (s, 6H, methyl at C-2).

EXAMPLE 24

Benzoyloxymethyl-D(-)-g-aminobenzylpenicillinate, hydrochloride 3.5 g of D(-)-a-aminobenzylpenicillin and 1.43 ml of triethylamine are mixed with 70 ml of acetone, which contains 1% water. To the resulting solution • add 1 g of potassium bicarbonate and 4.0. g bromomethylbenzoate, after which the mixture is stirred at room temperature for 4 hours. After filtration, the filtrate is concentrated in vacuo to about 15 ml, 100 ml of ethyl acetate is added, and the resulting solution is washed with aqueous sodium bicarbonate followed by water. Then 30 ml of water is added to the ethyl acetate solution, and with vigorous stirring, 1-1 hydrochloric acid is added dropwise, until the pH value of the aqueous phase is 2.5. The aqueous layer is separated and washed with ether. 150 ml of n-butanol is added, and the resulting mixture is evaporated in vacuo until the water is removed. The resulting butanol solution of 40 ml is poured into 500 ml of ether, whereby an amorphous precipitate separates. This is filtered off, washed with ether and dried, whereby the hydrochloride of the ester desired therein is obtained as a colorless product, which is identical to the product according to example 22 B.

Claims (1)

Analogy method in the production of therapeutic ak tive α-aminobenzylpenicillin esters with the general formula where the asterisk indicates the presence of an asymmetric carbon atom, and where A is a primary, secondary or tertiary alkyl group with. 1-4 C atoms or a phenyl or pyridyl group as well as salts of these esters with pharmaceutically acceptable acids, characterized by) that a ct-substituted benzylpenicillin is reacted with the general formula where the asterisk has the meaning mentioned above, and in which R means an amino group with the general formula 2-NH-, where Z stands for a usual protecting group or for hydrogen, or R means an azido group, nitro group or a bromine atom, and Y means a hydrogen atom, an alkali cation or a tertiary ammonium group, or a salt of a compound of formula II, with a compn share with the general formula III where X means a chlorine or bromine atom, an acyloxy group with 1-16 C atoms, an alkylsulfonyloxy or arylsulfonyloxy group, and A has the meaning stated above, while forming a compound of the general formula IV where R, A and the star have the above meaning ning-, after which any protective group present for the amino group is removed in the usual way or, if R means an azido or nitro group, this is hydrogenated, or if R is a bromine atom, this compound is reacted with hexamethylenetetramine, after which the thus formed compound of formula I, if desired , is transferred to a salt thereof with a pharmaceutically acceptable acid, or b) that one reacts an acid halide, acid anhydride or mixed anhydride with an alkylcarboxylic acid, a carboxylic acid, an inorganic acid or a sulphonic acid, or the reaction product with a carbodiimide or an N,N<1->carbonyldiimidazole of an acid. with the general formula V where R and the asterisk have the above-mentioned meaning, with a 6-aminopenicillanic acid ester of the general formula VI where A has the meaning mentioned above, and X<* >means a hydrogen atom or a trialkylsilyl group with a maximum of 5 C atoms in the alkyl residue, to a compound of the general formula IV, after which this, if necessary, is transferred to a compound of formula I or a salt thereof in the manner stated under method a).