DE2335083A1 - AMINO ACID ESTER - Google Patents

Description

Amino acid ester

The invention relates to the production of esters of N-blocked or N-protected amino acids.

There is a growing need for esterification processes which can be applied to such acids without destroying their molecular geometry, i.e. without molecular Cleavages or molecular rearrangements, such as isomerization and racemization. Such processes are particularly useful in the manufacture of cephalosporin and penicillin antibiotics needed where it is often necessary to protect a carboxyl group by esterification in order to take part in chemical conversions to be able to carry out other parts of the molecule.

The esterification of penicillin and cephalosporin compounds is undesirable because of the ease with which a number of things occur Side reactions fraught with difficulties. For example:

1. the ß-lactam ring easily under very mild conditions be opened. In the presence of acids, an un-

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desired reaction between the secondary amide group and the ß-lactam ring, especially in the case of penicillins.

2. In addition, in the presence of acids, the 4-carboxyl group in cephalosporins which contain various functional groups at C-3, eg CH ₂ OH or CH ₂ OCOCH, easily form an f-lactone ring.

3. In addition, the carboxyl group of both penicillins and cephalosporins enter into further reactions. For example, in ester formation reactions in the presence of bases rearrange the penicillins to anhydro-penicillins, and the cephalosporins can be mixtures of 2-em and 3-em products result.

It may be necessary to remove the carboxyl protecting group of penicillins, and remove cephalosporins upon completion of the desired chemical conversion. This leads to the further Necessity that the carboxyl protecting group should have such a structure that it can be easily used in the later process can be removed under mild conditions. Protecting groups of this type include diphenylmethyl and p-methoxybenzyl.

Because of these difficulties, those are usually convenient and cheap esterification methods for the esterification of N-blocked amino acids, such as penicillins and cephalosporins, for protection purposes of limited vert.

It has now been found that various esters are useful under mild conditions using a combination of one primary amine and a nitrosating agent as esterification mini tt el can be obtained. The esterification using such an agent is particularly suitable for N-blocked amino acids applicable that have a ß-lactam structure contain, e.g. penicillin and cephalosporic acids, as well as on

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other N-blocked amino acids and N-blocked peptides.

According to one embodiment of the present invention a process for the preparation of an ester of an N-blocked Amino acid created, which consists of the N-blocked amino acid or a salt thereof with an amine of the formula HNHp (where R is an organic group, e.g. Hydrocarbon group, is) and a nitrosating agent to react to form an N-blocked amino acid ester in which the ester group has the formula -COOR (where R has the meaning defined above).

If a salt of the N-blocked amino acid is used, then this a salt either with the amine RNH ^ or with a other base (e.g. an alkali metal salt, e.g. a potassium or lithium salt). These salts and especially those with an amine formed can be preformed, and it is of course not necessary to use them in the presence of the to form nitrosating agent. For example, you can use a salt made up of the amine and the N-blocked amino acid was formed, react with a nitrosating agent.

The esters obtained can thus through the form}. Q-COOR shown (where R is as defined above and Q-COOH is the N-blocked amino acid). Q can be a group containing 1-50 carbon atoms. the Acid can be a mono-, di- or polycarboxylic acid.

The group R preferably contains 1-30 carbon atoms, in particular 5-20 carbon atoms. Thus, R can be selected from, for example, cycloalkyl groups which contain 5-7 carbon atoms in the ring, for example cyclopentyl or cyclohexyl; Aralkyl groups which contain 1-3, preferably 1 or 2 aryl groups, these aryl groups preferably _{being bonded to the C-1 carbon atom of a lower (C, 6} ) alkyl radical, e.g. benzyl, diphenylmethyl, trityl, 9-fluorenyl, 9- Xanthydryl, etc .; heterocyclically substituted lower alkyl

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groups in which the alkyl part contains one or more 3- or 6-membered heterocyclic rings which contain one or more of the heteroatoms O, N and S, for example 2-thienylmethyl or 2-furylmethyl; or any of the above groups bearing one or more substituents selected from halogen, for example chlorine or bromine; Cyano; Nitro; Lower alkyl, for example methyl, ethyl or n-propyl; Lower alkoxy, for example methoxy, ethoxy or isopropoxy; Lower alkoxycarbonyl, for example methoxycarbonyl; and lower alkyl sulfonyl, for example methyl sulfonyl. The lower alkyl and lower alkoxy groups just mentioned can contain 1-6 carbon atoms.

As indicated above, it is particularly desirable to esterify the N-blocked amino acid with an ester-forming group R which can then be conveniently removed under mild conditions _{, therefore the amine RNH 2} is preferably selected to introduce such a group. Suitable amines thus include diphenylamine; ring-substituted diphenylmethylamines, for example di (ο-methylphenyl) diethylamine, di (p-methoxyphenyl) methylamine; Benzylamine; ring-substituted benzyl amines, for example p-nitrobenzylamine and lower alkoxyCC ,, gO-benzylamines such as p-methoxybenzylamine; 9-amino-fluorene; and heterocyclic alkyl amines such as 2-kurfurylamine.

The method of the invention is generally preferred applied to the preparation of esters in which R is an alkyl (e.g. methyl) group which is substituted by at least one aromatic carbocyclic or aromatic heterocyclic group is substituted.

The nitrosating agent can be any compound known as Serves as a source of nitroso groups, and is generally a compound of the formula NOX, wherein X is an organic or inorganic

2? nical anion or a group OR, in which R is an organic Group is. X can thus be an organic anion derived from a carboxylic acid, e.g. an alkanecarboxylic acid, which

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Contains 2-7 carbon atoms; Nitrosating agents of this type include acetyl nitrite and propionyl nitrite. If X is an inorganic one Anion, this can for example be derived from a mineral acid, e.g. a halide ion such as chloride or Bromide, or a sulfate ion, or from a Lewis acid such as a boron fluoride ion. Other inorganic anions include Hydroxide and sulfonate. These types of nitrosating agents include Nitrasyl chloride, nitrosyl sulfate, nitrosyl borofluoride, Nitrous acid and Fremys salt (potassium nitrosyl disulfonate).

ρ
If X is a group of the formula OR, the organic group R can, for example, be a lower alkyl group which preferably contains 1-9 carbon atoms, for example ethyl, n-propyl, isopropyl, η-butyl, t-butyl or isopentyl. Suitable nitrosating agents of this type include isopropyl nitrite, isobutyl nitrite, isoamyl nitrite and t-butyl nitrite.

The esterification is preferably carried out in an organic solvent or a mixed solvent. The organic solvent is preferred, but not essential inert. Organic solvents that can be used include chlorinated hydrocarbons, e.g. Methylene chloride, chloroform, 1,1-dichloroethane and 1,2-dichloroethane; Ethers and cyclic ethers such as diethyl ether, dioxane and tetrahydrofuran; aromatic hydrocarbons, e.g. Benzene and toluene; aliphatic esters such as ethyl acetate and Butyl acetate; Ketones, e.g., acetone; Amides, e.g., dimethylformamide and dimethylacetamide; aliphatic nitriles such as acetonitrile; Alkyl nitrires, e.g., isopropyl nitrite; Alcohols, e.g., methanol and Bircanol; and sulfoxides, e.g., dimethyl sulfoxide. Alcohols react with nitrossyl chloride and it is therefore preferred to use them not to be used with this nitrosation melon. Alternatively, however, less satisfactorily, the reaction can be carried out in an aqueous reaction medium, preferably a mixture of Water and an organic solvent such as a water-immiscible organic solvent such as chloroform. The material to be esterified should

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BATH ORIGINAL

be at least partially soluble in the chosen solvent.

The esterification can expediently be carried out at a temperature in the range from -50 ° to + 10O ⁰ C, for example -JO ⁰ to + 100 ⁰ C ₁ . Temperatures of + 10 ° to 75 ⁰ C are preferred with weak nitrosating agents (for example isopropyl), and temperatures from -30 ° to +20 ⁰ C with strong nitrosating agents (eg nitrosyl chloride). The reaction times depend, among other things, on the reaction temperature and the reactivity of the amine RKHp, but are normally in the range from 15 minutes to 24 hours.

The course of esterification can be tracked by nitrogen development that occurs in the reaction can be monitored. In general, an excess of the Esterifying agent used, if for example alkyl nitrites are used as nitrosating agents, then 1-3 »are preferred about 1.75 moles of amine and 1-5, preferably about 3.5 moles of nitrosating agent per mole of N-blocked amino acid used. If reactive nitrosating agents such as nitrosyl chloride are used, for example 1-4, preferably about 2.5 moles of the amine and 1-4, preferably about 2.5 moles of the Nitrosating agents can be used per mole of N-blocked amino acid. The cessation of gas evolution under such conditions usually corresponds to the completion of the esterification. The reaction can also be carried out by thin layer chromatography or Electrophoresis can be followed.

The reaction components can be brought together in various ways. For example, in the case of Alkyl nitrites, the amine and the nitrosating agent are brought together in a suitable solvent and then brought into contact with the N-blocked amino acid,

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An alternative method is to mix the N-blocked amino acid and the amine beforehand, using a salt of the formula Q-COONELR (where Q and R are as defined above); this salt is then mixed with the Nitrosating agents implemented for esterification. Similarly, the N-blocked amino acid (preferably in the form a salt) are premixed with the nitrosating agent and the product is then treated with the amine

The method according to the invention can generally be used for the esterification of N-blocked amino acids and peptides. It is particularly valuable for esterifying the carboxyl group or groups in intermediate compounds that are at the production of synthetic or semi-synthetic biologically active compounds such as ß-lactarn antibiotics involved.

The inventive method is particularly suitable for the case that a sulfur atom in the N-blocked amino acid is present, since the sulfur is usually not attacked by the reagents used. For example, it is at the production of cephalosporin and penicillin antibiotics often necessary to have a carboxyl group in a · carboxyl group-containing Protect ring system through esterification to a chemical transformation at another point of the molecule to be able to perform. An important example of this is in the ring expansion process for making Cephalosporin antibiotics made from penicillin compounds, as for example in Belgian patents 74-7 118, 74-7 119 and 74-7 120 is described.

The penicillin and cephalosporin compounds mentioned in the present specification are described with reference to FIG Cepham (J. Amer. Chem. Soc. 1962, 84 *, 34-00) and Penam (J. Aaer. Chem. Soc. 1953, 75 »3293) generally referred to. The expression "Cephem" means a basic cepham structure with one double bond.

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N-blocked amino acids according to the invention Methods that can be esterified include penicillin and cephalosporin compounds that have the backbone formula

(II)

where Z has the meaning of> S or> S - »0 (cc- or ß-); X is a divalent group selected from

■ CH

3. ·

CH.

(a)

COOH

(b)

COOH

(where Y is methyl; substituted methyl, e.g., -CHpY ¹ , where Y ^{1 is} the residue of a nucleophile, including such groups as acetoxy, hydroxy or carbamoyloxy; or an unsaturated group such as vinyl or substituted vinyl and the interrupted Line between the 2-, 3- and 4- positions of (b) indicates that the compound can be a ceph-2-em or ceph-3-em compound) and R is a blocked amino group, for example a carbocyclic acylanido group (which contains e.g. 1-20 carbon atoms) or a protonated amino

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ORiQlNAL INSPECTED

group (NIU ⁺ ). In particular, the invention can be applied to the case Z is> S

If R is a carbocyclic acylamido group, this can can be chosen from the rich selection of acyl groups mentioned in the penicillin and cephalosporin literature. in the The following are, without this being meant to be limiting, illustrate specific acyl groups:

(i) R ^u C _n H _2n C0-, where R ^{u is} aryl (carbocyclic or heterocyclic), cycloalkyl, substituted aryl, substituted cycloalkyl, cycloalkadienyl or a non-aromatic heterocyclic or mesoionic group and η is the meaning of O or a whole Number from 1 to 4 · has. Examples of this group include phenylacetyl; Thien-2- and -3-ylacetyl; 4-isoxazolyl and 4-isoxazolylacetyl are each substituted or unsubstituted; Pyridylacetyl, tetrazolylacetyl or a sydnonacetyl group.

(ii) 0 Hp -CO-, where η is the meaning of O or a whole Has number from 1 to 7. The alkyl group can be straight or branched and can be substituted by, for example, a cyano group, a carboxy group, an alkoxycarbonyl group, a Hydroxy group, an amino group or a carboxy-carbonyl group? (-CO.COOH) or by each of these groups in which the functional group is blocked. Examples of such groups include pormyl, glutaroyl, «f-aminoadipoyl and N-benzoyl- <f-aminoadipoyl.

R ^v

(iii) R ^U ZC-CO-, where R ^{u has} the meaning given under (i) R ^w

and can additionally be benzyl and R ^v and R ^w , which can be the same or different, each represent hydrogen, phenyl »benzyl, phenethyl or lower alkyl and Z is an acid

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is substance or sulfur atom. Examples of this group include phenoxyacetyl or pyridylthioacetyl.

(iv) hydrocarbyl oxycarbonyl and substituted hydrocarbyl oxy groups (wherein the 6- or 7-amino group forms part of a urethane), especially lower alkoxycarbonyl groups (such as methoxycarbonyl, ethoxycarbonyl and particularly preferably t-butoxycarbonyl groups); Halogen-lower alkoxycarbonyl groups, e.g. 2,2,2-trichloroethoxycarbonyl-; Aralkoxycarbonyl groups such as benzyloxycarbonyl, 4 ~ methoxybenzyloxycarbonyl, Diphenylmethoxycarbonyl and 4-nitrobenzyloxycarbonyl groups. Cycloalkoxycarbonyl groups are also advantageous especially the adamantyloxycarbonyl group.

(v) R ^U .CH (X) .CO-, where R ^{u has} the meaning defined under (i) and X is amino, substituted amino (for example acylamido or a group which is formed by reaction of the -aminoacylamido group of the 6- or 7th Side chain with an aldehyde or ketone, e.g. acetone, methyl ethyl ketone or ethyl acetoacetate), hydroxy, carboxy, esterified carboxy, azido, triazolyl, tetrazolyl, cyano, halogeno, acyloxy (e.g. formyloxy or lower alkanoyloxy) or etherified hydroxy groups. Examples of such acyl groups are α-aminophenylacetyl and pecarboxyphenylacetyl. It can be seen that if X is amino, this group will normally be blocked before an acid containing this particular acyl group can be used in the process of the invention.

It can be seen that the basic formula II includes in its structure compounds which are not specifically identified by the groups (a) and (b), e.g., 2β-acetoxymethylpenicillins, 2-methyl- and 2-methylencephalosporins, 6c * -methoxypenicillins and 7 "-methoxycephalosporins.

Compounds of the formula (lib) in which Y ^{1 is} the radical of a nucleophile can be prepared by reacting the. Connection of

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Formula (lib) wherein Y ^{1 is} acetoxy with a nucleophile such as pyridine or a tertiary amine as described in British Patent 912 541; a sulfur-bound, nitrogen-bound, or inorganic nucleophile as described in British Patent 1,012,943; a sulfur-linked nucleophile as described in British Patent 1,059,562; a nitrogen-bonded nucleophile as described in British Patents 1,030,630, 1,08294-3 and 1,082,962; or a sulfur-bound nucleophile as described in British Patents 1,101,423 and 1,206,305. This list is for illustrative purposes and is not a restriction.

Compounds of formula (Ub) in which Y 'is a hydroxyl group can be prepared according to the methods described in British patent specification 1,121,308; Compounds in which Y ^{1 is} a carbamoyloxy group are described in Belgian patent 764 160.

If Y in the formula (lib) is a methyl group, the compound can by the method described in British Patent 957,569. t

The following examples serve to illustrate the invention. All temperatures are in ⁰ C.

example 1

3 »96 g (10 mmol) of 3-acetoxymethyl-7β- (2-thienylacetamido) -ceph-3-em-4-carboxylic acid were in 50 ml of acetonitrile and 5 ml of dinethylacetamide solved. To this solution, a mixture of 2.4 g (27 mmol) of isopropyl nitrite and 2.21 g (12 mmol) of diphenyl

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- ■ - 12 -

methylamine, dissolved-suspended in 20 ml of acetonitrile added. The resulting slurry was stirred at 35 for three hours after which time a solution was obtained. The solvents were removed in vacuo and the gummy mass redissolved in 50 ml of chloroform. The solution obtained was with 50 ml 55 & Lger sodium bicarbonate solution and then with Washed 50 ml of water and the chloroform was removed in vacuo. The gummy mass became from 28 ml of hot Isopropyl alcohol crystallized, the crystals were with 25 ml of cold isopropyl alcohol and then washed in vacuo at room temperature to give 3 »19 g (56.8%, based on the acid used) of the title compound dried. The melting point and the mixed melting point with a authentic sample of the ester were at 140-140.5 °. The bicarbonate extract was washed with 10 ml of ethyl acetate and then acidified with 2N sulfuric acid at 5 ° to pH 1.2. The suspension was stirred for 30 minutes, filtered and washed with? 0 ml of cold water. The recovered Starting material was dried in vacuo at room temperature (0.9 g, a single spot in the thin layer chromatogram, UV determination).

Recovering some starting material gave the corrected 73-5 % yield of diphenylmethyl ester.

Example 2

carbojcjlat

3 »50 g (10 mmol) of 6β-phenoxyacetamido-2,2-diinethylpenam-3-xcarboxylic acid were added to a mixture of 2.40 g (27 mmol) of isopropyl nitrite and 2.21 g (12 mmol) of diphenylmethylamine in 50 ml of tetrahydrofuran were added at 35 ° and the mixture was stirred for three hours. The solution was removed in vacuo and the gummy mass dissolved in 50 ml of chloroform; the solution was with 50 ml

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5% sodium bicarbonate solution and then with 50 ml Washed with water, leaving a gummy mass of the title eater stayed behind. Yield 2.11 g (40.8%, based on the amount used Fenicillic acid).

Example 3

3 * 50 g (10 mmol) of 6β-? Enylacetamido-2,2-aimetliylpenam-3otcarbonsäure-1ß-oxide were added to a mixture of 2.40 g (27 mmol) isopropyl nitrite and 2.21 g (12 mmol) biphenylmethylamine and 50 ml Tetrahydrofüren added and stirred for two hours at 35 °. The solvent was evaporated _$ 50 ml of chloroform were su added to the rubber-like cash, and the resulting solution was washed with 50 ml of 5% Katriumbicarbonatlosung and then washed with 30 ml of water "After removal of the chloroform the gusnniartige Hasse from 25 ml of hot isopropyl alcohol was crystallized 3i33 B (64.5 %, based on the penicillic acid used) of the title compound was obtained; The melting point and melting point with an authentic sample of the ester were about - 146 °.

The bicarbonate wash water was treated and acidified as described in Example 4, 2.08 mmol of the acid used being obtained.

Taking into account the acid recovered, a corrected yield of 81.5 % of the ester based on the acid consumed was obtained.

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Example 4

0.97 g (12 raMol) furfurylamine and 2.4 g (27 mmol) isopropyl nitrite, dissolved in 10 ml acetonitrile, added at 35 °. The slurry was held at 35 ° with stirring for two hours, a solution forming after the first hour. After removing the solvent iac vacuum, 50 ml of the ethyl acetate did solution of the residue with 50 ml of 5% sodium bicarbonate and then washed with 200 ml of water. The partially solid organic residue was crystallized from 100 ml of isopropanol after evaporation of the solvent, giving 2.19 g (4.6, BiMoI, 46 % yield) of the previously unknown title ester of P> 161 °. An analytical sample of the ester, crystallized from methanol, had a melting point of 163 °; ν max (1% CHBr ^ solution) 3370 (-NHCO-), 1772 (β-lactam), 1730 + 1220 (acetate), 1720 parts by weight of β-unsaturated ester), 1672 + 1502 cm " ¹ (amide-carbonyl ); T (10 % CDCl ₅ ) 2.65-3.10 (multiplet, thienyl ring), 6.17 (singlet, thienylmethylene acetamido group Hp), 3.55 (doublet, J 9 Hz, amide nitrogen proton H. ), 4.19 (double doublet, J 9.5 Hz, C-7 H), 5.05 (doublet, J 5 Hz, C-6 H), 6.33, 6.72 (two doublets / "branches of one Quartet /, J 18 Hz, C-2 H ₅ ), 4.90, 5.22 (two doublets / branches of a quartet /, J 14 Hz, 3-acetoxymethyl), 7.97 (sinsulet, 3-acetoxyethyl H, ), 4.75 (singlet, furylmethyl group H ₂ ), 2.57 (multiplet, 5-furyl H) and 3.45-3.70 (Kultiplette, 3,4-furyl H ₃ ).

Analysis: (C ₂₁ H ₂₀ N ₂ O ₇ S ₂ )

Calculated: C 52.9 H 4.2 N 5.9% found: 53.1 4.3 5th, 7th

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Acidification of the bicarbonate extract gave 1.27 g (3.11 mmol) of the starting material acid of F * 149.5 ° »whereby a corrected yield of 66.8% based on the really used acid, calculated.

Example 5 .

4-carboxy_lat

A solution of 2.4? g (24 mmol) of isobutyl nitrite and 1.20 g (12 mmol) of cyclohexylamine are added to 20 ml of acetonitrile. The resulting slurry was stirred for two hours at 45 °, after which 15 nil more dimethylacetamide was added and stirred for 17 hours at 35 °. To the organic residue, after evaporation of the solvent, 50 ml of ethyl acetate was added, and the organic layer was washed with 40 ml of 5% sodium bicarbonate solution and with 50 ml of water. The organic residue was crystallized from 25 nil isopropanol, 1.10 g (2.29 mmol, 22.9 % yield) of the hitherto unknown title ester having a melting point of 165 ° -166 °. An analytical sample of the ester had a melting point of 169 °; v> max (1 % CHBr ^ solution) 3420 (-! 5HCO-.), 1790 (ß-lactam), - 1740 + 1245 (acetate), 1725 + 1228 (* ß-unsaturated ester), 1686 + 1515 cm "* ¹ (amide-carbonyl); τ (5 % CDC1,) 7.95 (singlet, 3-acetoxymethyl), 5.38, 6.73 (two doublets ΓΖν / one quartet], J 18 Hz), 6 , 18 (singlet, Tliienvlmethylpn-aee + a!? Dio-e: rupne), 4.88, 5.22 (two doublets / branches of a quartet /, J 14 Hz), 4.18 (double doublet, ■ J 9, 5 Hz, C-7), 5.05 (doublet, J 5 Hz, C-6), 3.52 (doublet, amide nitrogen proton), 2.67 - 3.03 (multiplet, thienyl ring) and 8 , 0 - 8.80 (inclusion, cyclohexyl).

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BATH ORIGINAL

Analysis ( ^C ₂ 2 ^H 26 ^N 2 ° 6 ^S 2 ^

calculated: C 55.2 H 5.5 N 5.9% found: 55.4 5.5 5.6

Acidification of the bicarbonate extract gave 2.24 g (5.64 mmol) of the starting material acid at F «149 °, whereby a corrected yield of 52.6% based on the really used acid.

Example 6

5.50 g (10 mmol) of Gβ-phenylacetamido- ^, 2-dimethylpena ^r n-3tfcarboxylic acid 1β-oxide were mixed with 2.21 g (12 mmol) of diphenylmethylamine and 2.14 g (24 mmol) of isopropyl nitrite in 50 ml of dioxane 6 hours at 35 °. warmed up. The solvent was removed in vacuo, replaced by 50 ml of ethyl acetate, and the reaction mixture was washed as described in Example 1. Crystallization from 25 ml of hot isopropanol of the gummy residue obtained after evaporation of the organic solvent gave 3.85 g (74.6%, based on the acid used) of the title ester, which was found to be pure by thin layer chromatography.

Acidification of the bicarbonate extract gave 2.08 mmol of the starting material acid, which is a corrected yield of 94.2% of the ester, based on the acid actually consumed.

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Example 7

carboxjlat

To a solution of 3.96 g (10 mmol) of 3-ethoxymethyl-7β- (2-thienylacetamido) -ceph-3-em-4-carboxylic acid in 70 ml of acetonitrile and 5 ml of dimethylacetamide were 1.28 g (12 mmol) Benzylamine and 2.47 g (24 mmol) of isobutyl nitrite added, and the mixture was heated to 45 ° for two hours. Initially, a solid formed in the mixture, but it did dissolved with vigorous stirring as the reaction progressed after 1-1.25 hours. After removing the solvent in vacuo, the gummy mass in 50 ml of ethyl acetate added, with 25 ml of dilute HpSO ^ ,, 50 ml of 5% NaHCO, solution and washed with 50 ml of water, and the organic. Residue became after evaporation of the organic solvent from hot isopropanol under BHctog of 2.40 g of the itel ester (42%, based on the acid used) from F = 135-139 ° crystallized. The thin layer chromatogram showed the presence from some traces of impurities.

Acidification of the bicarbonate extract gave 1.85 g (4.67 mmol) of the starting material acid, which resulted in a corrected yield of 78.8 % of the ester based on the acid actually consumed.

Example 8

carboxy_lat

3.48 g (10 mmol) 3-methyl-7ß-phenoxyacetamidoceph-3-em-4-carboxylic acid, 3.20 g (17.5 mmol) of diphenylmethylamine and 3.12 g (35 mmol) of isopropyl nitrite were in 50 ml of acetonitrile heated to 35 °. The solvent was removed in vacuo, replaced by 50 ml of ethyl acetate and, as in the

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Example 7 described, washed. The organic residue was extracted from 30 ml of hot isopropanol to give 4.25% (82.6%, based on the acid used) of the title ester with a melting point of 155 ° which is identified by thin layer chromatography as proved pure, crystallized.

Example 9

3.48 g (10 mmol) of 3-methyl-7β-phenoxyacetamidoceph-3-em-4-carboxylic acid were dissolved with 17.5 mmol of 9-aminofluorene in 50 ml of dichloromethane together with 3.62 g (35 mmol) of isobutyl nitrite and 18 Heated to 35 ° for hours. The reaction mixture was worked up as in Example 7, but a small amount of ester (0.24 g, 0.48 mmol) was filtered off from the solution after the acidic aqueous wash. After the solvent had been removed, the crystalline ester was slurried with 50 ml of warm isopropanol, cooled and filtered, giving 2.60 g of the previously unknown title compound with a melting point of 214 °, which was found to be pure by thin layer chromatography. Including the previously filtered solid, the weight of the isolated ester represents a yield of 56.8%, based on the acid used. An analytical sample of the ester, crystallized from acetone-methanol, had a melting point of 221-222.5 ° ; \> max (1 % CHBr, solution 3390 (-NHCO-), 1778 (ß-lactan) 1718

-1 («β-unsaturated ester), 1688 + 1520 cm (amide-carbonyl); Z (8% CDCl, solution), 2.2-3.2 (complex, phenoxy ring + (-NHCO-) + fluorenyl 9-C + fluorenyl ring), 5.47 (singlet, phenoxymethylene acetamido group, H ₂ ), 4.20 (doublet of doublets, J 10, 5 Hz, C-7, H), 5.04 (doublet, J 5 Hz, C-6, H), 6.45 + 6.89 (two doublets / Branches of a quartet /, J 18 Hz, H ₂ ), 7.84 (singlet, C-3, H,).

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H ₂₄ N 2 ° 5 ^S. ι) H 4.72 N 5.4 ' 2335083 Analysis (° 29 σ 67, 97 4.64 5.4 ' calculated: 67, 68 7% found: 7th

Acidification of the bicarbonate extract gave 0.37 g (1.05 mmol) of the starting material acid, which resulted in a corrected yield of 63.5% of the ester based on the acid actually consumed.

Example 10

TriOhenylmethyl-3 ~ ^{methyl-7.beta.-phenoxyacetamidoceph-3-em-I} l- carboxjlat

To 3.43 g (9.5 mmol) of 3-methyl-7β-phenoxyacetamidoceph-3-eia-4-carboxylic acid in 50 ml of dichloromethane were added 4.3 g (16.6 mmol) of triphenylmethylamine, 3.43 S (33, 2 mmol) of isobutyl nitrite and 5 g of anhydrous sodium sulfate were added, and the mixture was heated to 35 ° for two hours. The cooled solution was washed with 30% of 5% sodium bicarbonate and with 30% of water. The organic solution was evaporated to a solid, the solid slurried in 40 ml of toluene, cooled, filtered and washed in slurry with 15 ml of cold toluene to give 2.88 g (50.0 % yield based on acid used) hitherto unknown title compound with a melting point of 182 °, which was found to be pure by thin-layer chromatography. v? max (1% CHBr ^ solution) 3380 (NHCO), 1775 (β-lactam), 1723 (α-unsaturated star) 1686 - 1518 cm "" ¹ (amide-carbonyl); t (1% CDClj solution) 2.2 - 3.2 (complex, phenyl rings + phenoxy ring + -JK), 5.41 (singlet, phenoxymethylene acetamido group, H ₃ ), 4.09 ( Doublet of doublets J 4.5, 9 Hz, 0-7, H) 4.95 (doublet, J 4.5 Hz, H), 6.51 + 6.97 (two doublets / branches of a quartet / J 18 Hz , H ₅ ), 8.08 (singlet, C-3, H,).

■ 3 09885 / U15

Analysis: (C ₅₅ H ₅₀ N ₂ O ₅ S)

calculated: C 71.18 IT 5.09 N 4.75% found: 70.63 5.16 4.52

Acidification of the bicarbonate extract gave 1.25 g (3.60 mmol) of the starting acid, which gives a corrected yield of 84.8% of the ester based on the acid actually consumed.

Example 11

3.50 g (10 mmol) 6ß-Pher.ylacetamido-2,2-dimethylpenam - 3c> £ - carboxylic acid 1ß-oxide were mixed with 3.22 g (17.5 mmol) of diphenylmethylamine and 3.60 g (35 mmol) of tert-butyl nitrite in 50 ml Dissolved 1,2-dichloroethane and heated to 45 ° for two hours. the The cooled reaction mixture was worked up as in Example 7 and the organic residue from 35 nil isopropanol crystallized, washed with 25 nil cooled isopropanol. This gave 4.75 g (92%, based on the penicillic acid used) of the title ester with a melting point of 126 ° -127 °. In the thin layer chromatogram showed the presence of a trace of contamination.

Example 12

3.96 g (10 mmol) of 3-acetoxymethyl-7β- (2-thienylacetanido) -ceph-3-em-4-carboxylic acid were in a mixture of 4Ό ml of 1,2-dichloroethane and 3.5 ml of dimethylacetarcide dissolved. This solution became

■ 3 09885 / U15

1.78 g (20 mmoles) of pyridine and 3.66 g (20 mmoles) of diphenylmethylamine added, whereupon some solid precipitated. 0.92 ml (20 inMol) were added to this mixture at -30 °. Nitrosyl chloride in 1-5 ml of 1,2-dichloroethane added, whereupon gas evolution occurred and the solution turned from green to yellow. The plague gradually dissolved over the course of three hours when the temperature rises slowly to room temperature. The reaction mixture was diluted with 20 ml of sulfuric acid, 50 ml of 5% sodium bicarbonate solution and 50 ml of water and the organic residue from 25 ml of isopropyl alcohol Formation of 1.39 g (2.4-7 mmol, 24.7% yield) of the title ester crystallizes with a melting point of 142 °.

Acidification of the bicarbonate solution gave 2.68 g (6.78 mmol) of the starting material acid at F * 144 °, whereby a corrected yield of 76.6% of the ester, based on the acid actually consumed, results.

Example 13

2.25 g (10 mmol) of D - (-) - N- (2,2,2-trichloroethoxycarbonyl) -2-phenylglycine, 4.58 g (25 mmoles) of diphenylmethylamine, 5 g of anhydrous sodium sulfate and 6.7 g of potassium carbonate added. 12.5 ml (iO% solution in Dichloromethane, 25 mmol) nitrosyl chloride were used during Added 10 minutes at -5 ° with vigorous stirring. The mixture was allowed to warm to about room temperature over 50 minutes, and 80 ml of water was added. The solid was filtered off and the organic solvent with 20 ml 1N sulfuric acid and 50 ml of water. The semi-solid, which remained after the evaporation of the solvent was rubbed with 50 ml of ether and the then pure solid was' combined with the previously filtered solid, in

309885/1415

slurry washed with 30 ml. ether and filtered, whereby one 3 »33 S (85%! Based on the acid used) of the title ester vom F »176, which can be identified by thin-layer chromatography proved to be pure, received.

Example 14

3 »50 g (10 mmol) of 6β-phenylacetamido-2,2-dimethylpenam-3cocarboxylic acid 1β-oxide were added to 50 ml of dichloromethane, the 4.77 g (25 mmoles) of diphenylmethylamine, 5 g of anhydrous sodium sulfate and 6.7 g of potassium carbonate. 12.5 ml (iO% ige Solution in dichloromethane, 25 mmol) nitrosyl chloride were added over 10 minutes with vigorous stirring at -5, and after the addition, the reaction mixture was allowed to warm to room temperature over 50 minutes. The mix was as described in Example 7, worked up and the organic residue recrystallized from 25 ml of hot isopropanol, wherein one 4.45 g (86.2%, based on the penicillic acid used) of the title ester from F »146 °, which can be determined by thin-layer chromatography proved to be pure, received.

Acidification of the alkaline extract gave 0.48 mmol of the starting material acid, which is a corrected yield of 90.5% »based on the acid actually used, results.

Example 15

carboxjlat

3.48g (10mMoI) 3-methyl-7ß-phenoxyacetamidoceph-3-em 4-carboxylic acid in 50 ml of dichloromethane with 3 »43 g

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(25 mmol) p-methoxy-benzylamine, along with 5 g of anhydrous Dissolved sodium sulfate and 6.7 S potassium carbonate. 12.5 ml CiO% solution in Di chlorine than, 25 mmol) nitrosyl chloride was en added over about 10 minutes at -5 ° with vigorous stirring. Some partial gel formation occurred which, however, dissolved again while the mixture was heated for another 50 minutes to room temperature was stirred. The reaction mixture was worked up as described in Example 7, and the organic residue was removed 25 ml of hot isopropanol to yield 2.38 g (50.6% yield, based on the acid used) of the title compound of P = 151-152 ° crystallized.

Acidification of the alkaline extractor gave 1.37 g (3,94-CiMoI) the starting material acid, which results in a corrected yield of 83.5% based on the real spent acid, yields.

Example 16

carbox ^ lat

3.28 g (9.4-2 mmol) of 3-methyl-7β-phenoxyacetamidoceph-3-em-4-carboxylic acid were in 50 ml of dichloromethane with 25 mmol of p-nitrobenzylamine, along with 6.7 g of potassium carbonate and 5 g of anhydrous Dissolved sodium sulfate. 12.5 ml (10% solution in dichloromethane, 25 mmol) nitrosyl chloride were added for about 10 minutes added with vigorous stirring at -5 °, and then the reaction mixture was allowed to counteract for 50 minutes Warm up to room temperature. The reaction mixture was worked up as described in Example 7 and the residue was removed crystallized from 25 ml of methanol, 0.78 g (17.9%, based on the acid used, the Ti-oelester from F * 176 - 181 °.

• 3 0 9.885 / U1 &

2 3 3. ^ Π 8

Acidification of the alkaline extract gave 2.56 g (7 »35 mmol) of the starting material acid, resulting in a ■ corrected yield of 82.2%, based on the actually consumed Acid.

09885 / 1AIb

Claims (20)

Claims 1. Process for the preparation of an ester of an N-blocked Amino acid, characterized in that the N-blocked Amino acid or a salt thereof with an amine of the formula RNHo (where R is an organic group) and a nitrosating agent to form an N-blocked amino acid ester in which the ester group has the formula -COOR. 2. The method according to claim 1, characterized in that R is an aralkyl group or an alkyl group with 1-6 carbon atoms + which carries a 5- or 6-membered heterocyclic ring which contains one or more of the atoms 0, N or S, where these groups can be unsubstituted or can be substituted by a 'halogen atom or a cyano, nitro, C ^^ ₆ -alkyl, C ^ _-6 -alkoxy-, alkoxycarbonyl- (which carries a C ^ c -alkoxy part) or C 1-4 alkylsulfonyl group. 3. The method according to claim 2, characterized in that R is an alkyl group formed by at least one aromatic carbocyclic or aromatic heterocyclic group is substituted. 4. The method according to claim 1, characterized in that R is a diphenylmethyl, benzyl, triphenylmethyl, 2-thienylmethyl or 2-furylmethyl group. 5; Method according to one of the preceding claims, characterized in that a nitrosyl halide is used as the nitrosating agent. 6. The method according to any one of claims 1 to 4, characterized characterized in that a C. g nitrite is used. -3 0 98 8 57 U1 5 7. The method according to "claim 5 or 6, characterized in that that nitrosyl chloride or isoporpyl nitrite is used as the nitrosating agent. 8. The method according to any one of the preceding claims, characterized in that it is in an inert organic Solvent is carried out. 9. The method according to any one of the preceding claims, characterized in that it is carried out at a temperature of ⁰ C to +100 -jō. 10. The method according to any one of the preceding claims, characterized in that an excess of the amine and the Nitrous oxide is used. 11. The method according to any one of the preceding claims, characterized in that the amine and an alkyl nitrite in a solvent and then brought into contact with the N-blocked amino acid. 12. The method according to any one of claims 1 to 10, characterized in that a mixture or a salt of the N-blocked Amino acid and the amine are treated with the nitrosating agent. 13 · The method according to any one of the preceding claims, characterized in that the N-blocked amino acid is a Penicillin or a cephalosporin is used. 14. The method according to claim 13, characterized in that the sulfur atom of penicillin or cephalosporin in the Sulphide form is present. 15 * Ester of an N-blocked amino acid, * available after Method according to claim 1. • 3 09885 / U15 16. 2 ceph-3-em-4-carboxylate. 17 · Cyclotiexyl 3-acetoxymethyl-7β- (2-thienyl acetamido) -ceph-3-ene-4-carboxylate. 18. Benzyl 3-acetoxymethyl-7β- (2- "chienyl8uctaniido) -ceph-3" -em ~ 4-carboxylate. 19.9-fluorenyl-3-ethyl-7ß-phenoxyacetamidoceph-3-ei3-4-carboxylate. 20. TΓiphenylπlethyl-3-πlethyl-73- · phenoxyacetalnidoceph-3-eπl-4-carboxylate. 309885/1 A1