CA1268780A - N-hydroxyl protecting groups and process for the preparation of 3-acylamino-1-hydroxy-2-azetidinones - Google Patents

Abstract

ABSTRACT
This invention relates to novel intermediates of the formula which are useful in the preparation of compounds of the formula

Description

~268~

NOVEL N-HYDROXYL PROTECTING GROUPS AND
PROCESS FOR THE PREPARATION OF
3-ACXhAMINO-l-HYDROXY-2-AZETIDINONES

United States patent 4,337,197, issued June 29, 1982, discloses as antibacterial agent~, 3-acylamino-2-oxo-1-azetidinyl sulfates. A3 inter-medi.ates for the preparation of these products, Unit.ed States patent 4,337,197 discloqes, inter alia, compounds having the formula Xl-NH -CH - C - X3 l l ~ N-OH , wherein Xl is acyl and X2 and X3 are hydroge~ or organic substituents including alkyl.

-2- GC222 This invention is directed to novel chemical compounds having the formula I ~H3 H2N-O-C-O-lower alkyl and II Rl-NH R2 . 0~ ~C\ O lower alkyl, and to processes for using compounds of formula I
and II to obtain compounds having the formula III Rl-NH ~ 2 C~ CH
~ ~ ~-OH .

The compounds of formula III are useful as intermediates for the preparation of antibacterial agents; i.e., 3-acylamino-2-oxoazetidin-1-yloxy acetic acids, which are disclosed in Belgium - patent 897,466, issued February 6, 1984, and

3-acylamino-2-oxo-1-azetidinyl sulf~tes, as disclosed in United 5tates patent 4,337,197, issued June 29, 1~82-In formulas I, II and III, and throughout the specification, the symbols are as defined below.
Rl is an acyl group derived from a carboxylic acid; and R2 is hydrogen, lower alkyl or carbamoyloxy-methyl.
The terms "lower alkyl" and "lower alkoxy", as used throughout the specification, refer to alkyl groups having 1 to 4 carbon atoms.
The compounds of formula II can be converted to the corresponding compound of formula III by simple 12687~0 GC222 treatment with a mild acid.
Alternatively, in those instances wherein R
is an acyl group derived from a carboxylic acid that is also an amino protecting group removable S under neutral or basic conditions (referred to hereinafter as "A1"), the compounds of formula II
can be converted to the corresponding compound of formula III using the following reaction sequence:

IV Al-NH C~ 2 CH H
C - N-O/C-O-lower alkyl CH ~ 1 H
- ~ C~ N-~ C\O-lower alkyl C~3 CH3 II Rl-NH cfJR2 CH
~ 1 N- ~ C ~O-lower alXyl o C~3 H3 III Rl-NH ~ 2 ~I
~ OH

The expression "an amino protecting group that is removable under neutral or basic conditions"
refers to any group which will protect the 1268~780

-4-nitrogen atom to which it is attached from reacting in the above sequence, and which, at the end of the above-described reaction sequence can be cleaved from the nitrogen atom at a pH equal S to, or greater than, 7Ø Exemplary of such groups are phenylmethoxycarbonyl and substituted phenylmethoxycarbonyl (e.q., phenylmethoxycarbonyl substituted with 4-methoxy, 4-chloro, 4-methyl, 2-methyl, 3-methyl, 2,4,6-trimethyl, 3,5-dimeth-oxy, 2-nitro, or 4-nitro), allyloxycarbonyl, cinnamyloxycarbonyl, vinyloxycarbonyl, 1,1-dimethylpropynyloxycarbonyl, 2-furanyl-methyloxycarbonyl, 2-methylthioethyloxycarbonyl, 2-trimethylsilylethyloxycarbonyl, 2-methylsulfonyl-ethyloxycarbonyl, 9-fluorenylmethyloxycarbonyl, 2,2,2-trichloroethyloxycarbonyl, 2-cyanoethyloxy-carbonyl, and 1,1-dimethyl-2-cyanoethyloxycarbonyl.

~2687ao The term "acyl" refers to all organic radicals derived from an organic acid (i.e., a carboxylic acid) by removal of the hydroxyl group. Certain acyl groups are, of course, preferred but this preference should not be viewed as a limitation of the scope of this invention. Exemplary acyl groups are those acyl groups which have been used in the past to acylate ~-lactam antibiotics including 6-aminopenicillanic acid and derivatives and 7-aminocephalosporanic acid and derivatives;
see, for example, Cephalosporins and Penicil-lins, edited by Flynn, Academic Press (1972), German Offenlegungsschrift 2,716,677, published October 10, 1978, Belgian patent 867,994, pu~-lished December 11, 1978, United States pat-ent 4,152,432, issued May 1, 1979, United States patent 3,971,778r issued July 27, 1976, United States patent 4,172,199, issued ~ctober 23, 1979, and British patent 1,348,894, pub-lished March 27, 1974. The portions of these references describe various acyl groups. The following list of acyl groups is presented to further exemplify the term "acyl"; it should not be regarded as limiting that term. Ex-emplary acyl groups are:
(a) Aliphatic groups having the formula O
Il R -C-wherein Ra is alkyl; cycloalkyl; alkoxy; alkenyl;

126~780 GC222 _6 --cycloalkenyl; cyclohexadienyl; or alkyl or alkenyl substituted with one or more halogen, cyano, nitro, amino, mercapto, alkylthio, or cyanomethyl-thio groups.
(b) Carbocyclic aromatic groups having the formula b~(CH2 ~ n~C~ ' Rc - ~ CH-C-Re Rb ~Rd )--CH2-O-C-, b ~ CH2 C

. ~ 268780 GC222 b ~ S-CH2-C- or b~ ~H2-S-C-wherein n is 0, 1, 2 or 3; Rb, Rc, and Rd each is independently hydrogen, halogen, hydroxyl,.
nitro, amino, cyano, trifluoromethyl, alkyl of l to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms or aminomethyl; and Re is amino, hydroxyl, a carboxyl salt, protected carboxyl, formyloxy, a sulfo salt, a sulfoamino salt, azido, halogen, hydrazino, alkylhydrazino, phenylhydrazino, or [(alkylthio)thioxomethyl]thio.
Preferred carbocyclic aromatic acyl groups include those having the formula HO ~ CH2-C-, o H2 -C--, GC~
8 ~.26~37~3~

HO ~ H-C- (Re is preferably a carboxyl salt or sulfo salt) and ~ CH-C- (Re is preferably e a carboxyl salt or sulfo salt).
(c) Heteroæ omatic groups having the formula Rf (CH2)n C , o Rf-CH-C-Rf--O--CH2--C--Rf--S--CH2--C-, O O
Rf-C -C-wherein n is 0, 1, 2 or 3; Re is as defined above; and Rf is a substituted or unsubstituted

5-, 6- or 7-membered heterocyclic ring containing 1,2,3 or 4 (preferably 1 or 2~ nitrogen, oxygen and sulfur atoms. Exemplary heterocyclic - 9 - lZ68780 GC222 rings are thienyl, furyl, pyrrolyl, pyridinyl, pyrazolyl, pyrazinyl, thiazolyl, pyrimidinyl, thiadiazolyl and tetrazolyl. Exemplary substituents are halogen, hydroxyl, nitro, amino, protected amino, cyano, trifluoromethyl, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, or HOOC-CH-CH2-0-C-NH- .

Preferred heteroaromatic acyl groups include those groups of the above formulas wherein R~ is 2-amino-4-thiazolyl, 2-amino-5-halo-4-thiazolyl, 4-aminopyrimidin-2-yl, 5-amino-1,2,4-thiadiazol-3-yl, 2-thienyl, 2-furanyl, or 6-aminopyridin-2-yl.
(d) ~(4-Substituted-2,3-dioxo-1-piper-azinyl)carbonyl]amino]arylacetyl groups having the formula ll 1l r~~\
: -C-ICH-NH-C-N N-Rh g O O
wherein Rg is an aromatic group (including carbocyclic aromatics such as those of the formula Rc and heteroaromatics as included within the definition of Rf); and Rh is alkyl, substituted lo- ~26~7ao GC222 alkyl (wherein the alkyl group is substituted with one or more halogen, cyano, nitro, amino or mercapto groups), arylmethyleneamino (i.e., ~N=CH~Rg wherein Rg is as defined above), O
arylcarbonylamino (i e., ~NH~C~Rg wherein R
i as defined above) or alkylcarbonylamino.
Preferred 1[(4-substituted-2,3-dioxo-1-piperazinyl)carbonyl]amino]arylacetyl groups include those wherein ~ is ethyl, phenylmethylene-amino or 2-furylmethyleneamino.
(e) (Substituted oxyimino)arylacetyl groups having the formula o -C -C=N-O--R
Rg wherein Rg is as defined above and Ri is hydrogen,-alkyl, cycloalkyl, alkylaminocarbonyl, arylamino-carbonyl (i.e., ~C~NH~Rg wherein Rg is as defined above~ or substituted alkyl (wherein the alkyl group is substituted with one or more halogen, cyano, nitro, amino, mercapto, alkylthio, aromatic group (as defined by Rg), carboxyl (including salts thereof), amido, alkoxycarbonyl, phenylmethoxycarbonyl, diphenylmethoxycarbonyl, hydroxyalkoxyphosphinyl, dihydroxyphosphinyl, hydroxy(phenylmethoxy)phosphinyl, or dialkoxy-phosphinyl substituents).

2 ~ ~ 7 8 0 GC222 Preferred (substituted oxyimino)arylacetyl groups include those wherein Rg is 2-amino-4-thiazolyl. Also preferred are those groups wherein Ri is methyl, ethyl, carboxymethyl, l-carboxy-l-methylethyl, 2,2,2-trifllloroethyl or l-carboxycyclopropyl.
(f) (Acylamino)arylacetyl groups having : the formula o O
-C-CH-NH-C-R
Rg wherein R is as defined above and Rj is R

Rb ~ (CH2)n-O-, amino, alkylamino, (cyanoalkyl)-amino, amido, alkylamido, (cyanoalkyl)amido, -CH2 -NH-C~N -CH-CH2 -C -NH-CH3, : ~ ~o2-N (CH2-CH2 ~H)2 ~ ~CH3 OH

~ 0 HO ~ ICI-O O

. GC222 _12 ~26~

Preferred (acylamino)arylacetyl groups of the above formula include those groups wherein Rj ls amino or amido. Also preferred are those groups wherein R is phenyl or 2-thienyl.
(g) ~[3-Substituted-2-oxo-1-imidazoli-dinyl]carbonyl]amino]arylacetyl groups having the formula O O "C~
-C-CH-NH-C-N N-Rk Rg CH2 -C~2 wherein Rg is as defined above and Rk is hydrogen, alkylsulfonyl, arylmethyleneamino ~i.e., ~N~CH~Rg wherein Rg is as defined above), -C-Rm (wherein Rm is hydrogen, alkyl or halogen substituted alkyl~, aromatic group (as defined by Rg above), alkyl or substituted alkyl (wherein the alkyl group is substituted with one or more halogen, cyano, nitro, amino or mercapto groups).
Preferred [[3-substituted-2-oxo-1-imidazoli-dinyl]carbonyl]amino]arylacetyl groups of the above formula include those wherein Rg is phenyl or 2-thienyl. Also preferred are those groups wherein Rk is hydrogen, methylsulfonyl, phenyl-methyleneamino or 2-furylmethyleneamino.

1268~8~ GC222 The novel chemical compounds of formula I, II
and IV, and the processes of this invention, are useful for the preparation of the hydroxamates of formula III. These hydroxamates can be used to prepare 3-acylamino-2-oxoazetidin-1-yloxy acetic acids and 3-acylamino-2-oxo-1-azetidinyl sulfates. As described in Belglum patent 897,466, is8ued February 6, 1984 and 10 United States patent 4,337,197, issued June 29, 1982, these compounds are ~-lactam antibiotics useful for combating bacterial infect~ons (including urinary tract infections and re~piratory infections) in mammalian species, such as domesticated animals and humans.
The novel carboxy protecting group (derived from a compound o formula I) used in compounds of formulas II, IV and V is extremely acid labile, and because of this, its removal from a compound of formula II or IV is a simple operation.
- The compounds of formula I can be prepared by first reacting N-hydroxyphthalimide with a 2-(lower alkoxy)propene to yield a compound having the formula o VI ~ N-O-C-O-lower alkyl The reaction is preferably run in the presance of - phosphorous oxychloride or pyridinium tosylate and an organic amine such as triethylamina or pyridine.
Co~version of an N-hydroxyphthalimide derivative of formula VI to the corresponding compound of formula I can be accomplished by treating the compound with hydrazine or an alkylhydrazine.

.

1 2 61847 8 ~ GC222 The compounds of formula II and IV can be obtained by first reacting a protected amino acid having the formula VII ~l-NH OH
CH ~H~R2 ~--0~

with a [(l-alkoxy-l-methyl)ethoxy]amine of formula I to yield the corresponding amide having the formula VIII Al-NH OIH
CH ~ CH~R2 NH-~ C~O-lower alkyl.
CH3 ~3 The reaction proceeds most readily if the protected amino acid of formula VII is first activated.
Activated forms of carboxylic acids are well known in the art and include acid halides, acid an-hydrides (including mixed acid anhydrides), activated acid amides and activated acid esters.
Mixed acid anhydrides for use in the process of this invention can be formed from an amino acid of formula VII and a substituted phosphoric acid (such as dialkoxyphosphoric acid, dibenzyloxyphosphoric acid or diphenoxyphosphoric acid), a substituted phosphinic acid (such as diphenylphosphinic acid or dialkylphosphinic acid), dialkylphosphorous acid, sulfurous acid, thiosulfuric acid, sulfuric acid, a carboxylic acid such as 2,2-dimethylpropanoic acid, a carboxylic acid halide such as 2,2-dimethyl-propanoyl chloride, and others. Exemplary of theactivated amides which can be used in the process of this invention are those formed from an amino acid of formula VII and imidiazole, 4-substituted imidazoles, dimethylpyrazole, txiazole, tetrazole or dimethylaminopyridine. Exemplary of the ~268~8~ ~C222 activated esters which can be used in the process of this invention are the cyanomethyl, methoxy-methyl, dimethyliminomethyl, vinyl, propargyl, 4-nitrophenyl, 2,4-dinitrophenyl, trichlorophenyl, pentachlorophenyl, mesylphenyl, phenylazophenyl, phenylthio, 4-nitrophenylthio, ~-cresylthio, carboxymethylthio, pyranyl, pyridinyl, piperidyl, and ~-quinolylthio esters. Additional examples of activated esters are esters with an N-hydroxy compound such as N,N-dimethylhydroxylamine, l-hydroxy-2(lH)pyridone, N-hydroxysuccinimide, N-hydroxyphthalimide, and 1-hydroxy-6-chloro-lH-benzotriazole.
The amides of formula VIII which result from the coupling of an amino acid of formula VII and a ~(1-alkoxy-1-methyl)ethoxy]amine of formula I
can be cyclized by first converting,the hydroxyl group to a leaving group, yielding a compound having the formula IX Al-NH l SO2 2 CH C~~R2 ~ C N~- ~ C ~ lower alkyl .

The conversion is accomplished by reacting a compound of formula VIII with a compound having the formula wherein X is chlorine or bromine and A2 is alkyl, phenyl or substituted phenyl (preferably methyl or p-methylphenyl). The reaction can be run in an organic solvent (e q., pyridine or dichloro-methane) in the presence of an organic base (e.q., triethylamine).

~268 7~0 GC222 Cyclization of a compound of formula IX to the corresponding 2-azetidinone of formula IV can be accomplished by treating a compound of formula IX with a base such as an alkali metal carbonate, bicarbonate or hydroxide; or a quaternary ammonium carbonate, bicarbonate, or hydroxide. The reaction is preferably carried out in water or a mixture of water and an organic solvent.
Alternatively, the 2-azetidinones of formula IV can be prepared directly from the corresponding compounds of formula VIII withou~ first converting the hydroxyl group to a leaving group. Treatment of a compound of formula VIII with triphenyl-phosphine and diethylazodicarboxylate yields a compound of formula IV.
Both of the methods disclosed above for ring closure of a compound of formula VIII result in the inversion of the stereochemistry of the R2 substituent.
Deprotection of the amino group of a compound of formula IV to obtain the corresponding compound of formula V can be accomplished using known procedures that will depend on the particular protecting group (A1) being removed.
Treatmen~ with hydrogen (using a catalyst such as palladium) cleaves a phenylmethoxycarbonyl or substituted phenymethoxycarbonyl protecting group.
Well known acylation techniques can be used to convert a compound of formula V to a compound of formula II. Exemplary techniques include reaction with a carboxylic acid (R1-O~) or corresponding carboxylic acid halide or carboxylic acid anhydride. The reactions with a carboxylic acid proceed most readily in the presence of a carbodiimide such as dicyclohexylcarbodiimide and ~2~i;878~) a substance capable of forming a reactive inter-mediate in situ such as N-hydroxybenzotriazole or 4-dimethylaminopyridine. In those instances wherein the acyl group (Rl) contains reactive functionality tsuch as amino or carboxyl groups) it may be necessary to first protect these functional groups, then carry out the acylation reaction, and finally deprotect the resulting product.
The [(1-alkoxy-1-methyl)ethoxy]amino protecting group can be readily cleaved from a compound of formula II or IV by treatment of the compound with acid.
Additional methodology for preparing the novel compounds of formulas II and IV will be apparent to the practitioner of this invention.
For example, a compound of formula IX can have its amino protecting group ("Al") cleaved and the resulting amino compound acylated prior to cyclization and cleavage of the [(1-alkoxy-1-methyl)ethoxy]amino protecting group. Still additional methodology comprises starting with an acylated amino acid having the formula XI Rl-NH OH
~H CH~R2 ~ C OH

reacting it with a [(l-alkoxy-1-methyl)ethoxy]-amine of formula I, cyclizing the resulting amide and the cleaving the [(l-alkoxy-1-methyl)ethoxy]-amino protecting group.
The following examples are specific embodiments of this invention.

~26878~ GC222 Example 1 [(l-~ethoxy-l-methyl)ethoxylamine A) N-[l-MethoxY-l-methyl)ethoxv]phthalimide N-Hydroxyphthalimide (40.7 g, 0.25 mol) was suspended in 160 ml of dry tetrahydrofuran. 2-Methoxy-propene (36 ml, 0.375 mol) was added followed by 1 drop of phosporous oxychloride. After 40 minutes, the solid had dissolved. Triethylamine (2 ml) was added and the tetrahydrofuran was evaporated. The residue was taken up in 500 ml of ethyl acetate, filtered, washed with aqueous sodium bicarbonate and then saturated aqueous sodium chloride, and dried over sodium sulfate.
The solvent was removed and the white solid residue wa~ dried under vacuum to afford 53.6 g of the title compound.

B) ~ Methoxv-l-methYl)ethoxylamine N-[l-Methoxy-l-methyl)ethoxy]phthalimide (80.4 g, 0.342 mol) was dissolved in 500 ml of dichloromethane. The mixture was cooled in an ice/water bath and stirred mechanically. Methyl hydrazine (27.5 ml, 0.513 mol) was added over 15 minutes. After an additional 15 minutes, the cold bath was removed and the mixture was stirred for 1 hour. The mixture was filtered, concentrated to a small volume, filtered again, and distilled under vacuum (60-70C, 20 mm of ~g) to afford 27.3 g of the title compound as a colorless liquid.

lZ~378~

Example 2 [3S-[3~Z),4~]]-3-[[(2-Amino-4-thiazolyl)(methoxy-imino)acetyl]amino]-l-hydroxy-4-methyl-2-azetidinone -A) N2-[(Phenylmethoxy)carbonyl]-N-[(l-methoxy-l-methYl)ethox~l-L-threoninamide A solution of 111.5g (0.677 mole) of N-[(phenylmethoxy)carbonyl]-L-threonine, 68.7g (O.679 mole) of triethylamine and 6.8g (O.086 mole) of pyridine in 1600 ml of dichloromethane was coled to -20C and 82.0g (0.680 mole~of pivaloyl chloride was added dropwise. After stirring for 15 minutes, 85.3g (0.812 mole) of [(l-methoxy-l-methyl)ethoxy]amine was added dropwise. After stirring for 30 minutes, the mixture was warmed to -15C and a solution of 101.7g (1.211 mole) of sodium carbonate in 1 liter of waker was added. The reaction mixture was allowed to warm to room temperature and the organic layer was separated. The aqueous solution was extracted with 400 ml of dichloromethane and the combined organic layers were dried with sodium sulfate. The solvent was concentrated to 400 ml and 1.5 liters of ethyl acetate was added. The solution was concentrated to 500 ml and after the addition of 50 ml of petroleum ether, the title compound started to crystallize. It was filtered of, washed with petroleum ether and dried ln vacuo, yielding 215.2g of the title compound, melting point 88C.

126~780 GC222 B) (3S-trans)-3-[[(Phenylmethoxy)carbonyl]amino]-1-[(1-methoxy-1-methyl)ethoxyl-4-methYl-2-azetidinone A solution of 20.4g (60 mmole) of N2-[(phenylmethoxy)carbonyl]-N-[(1-methoxy-1-methyl)-ethoxy]-L-threoninamide and 6.lg (60 mmole) of triethylamine in 200 ml of ethyl acetate was cooled to -2C, and 6.9g (60 mmole) of methane-sulfonyl chloride was added dropwise. After stirring for one hour, the mixture was washed with ice-cold water, sodium bicarbonate and brine. The solution was filtered over ~yflo, and 24g (174 mmole) of potassium carbonate was added. After stirring overnight at ambient temperature, the potassium carbonate was filtered off, and the filtrate washed with ice-cold sodium bicarbonate and brine, dried wi~h sodium sulfate and evaporated to dryness, yielding 17.8g of the title compound as a slightly yellow oil.

C~ [3S-[~a(Z),4~]-3-[[(2-Amino-4-thiazolyl)-(methoxyimino)acetyl]amino]-1-[(1-methoxy-1-methvl)ethoxYl-4-methyl-2-azetidinone (3S-trans)-3-[[(Phenylmethoxy)carbonyl]amino]-1-[(1-methoxy-1-methyl)ethoxy]-4-methyl-2-azetidinone (9.Og, 27.9 mmole) was dissolved in 100 ml of dimethylformamide, and 2.0g of 10% palladium on charcoal was added. Hydrogen was bubbled through the mixture for one hour at ambient temperature and the catalyst filtered off. (Z)-2-Amino-4-thiazoleacetic acid (5.7g, 27.9 mmole), 0.5g (3 mmole) of N-hydroxybenzotriazole and 6.3g (30.6 mmole) of dicyclohexylcarbodiimide were added to the filtrate and the resulting mixture was stirred for three hours at amibent temperature. The solvent was evaporated ln vacuo and the residue 12~8785~ GC222 was taken up in ethyl acetate. After washing with cold sodium bicarbonate and brine, the organic layer was dried with sodium sulfate and evaporated in vacuo. The residue was purified by column chromatography on silica gel using ethyl acetate as solvent, and yielding 4.0g of the title compound, melting point 101C, dec.

D ) [3S- [3a ( Z ), 4~ ] ] -3- [ [ ( 2-Amino-4-thiazolyl)-(methoxyimino)acetyl]amino]-1-hydroxy-4-methyl-2-azetidinone [3s-[3a(z),4~]]-3-[[(2-Amino-4-thiazolyl)-(methoxyimino)acetyl]amino]-l-[(1-methoxy-1-methyl)ethoxy]-4-methyl-2-azetidinone (O.5 3 g) was dissolved in 2 ml of methanol, and 10 ml of water was added. The pH was adjusted to 3 . O by adding lN hydrochloric acid, and the mixture was stirred for 10 minutes at room temperature. The methanol was evaporated ln vacuo, and the resulting aqueous solution freeze-dried yielding 0.43g of the title compound, melting point 188C, dec.

Exam~le 3 (3S)-3-[[(Phenylmethoxy)carbonyl]amino]-l-hydroxy-2-azetidinone A) NZ-[(Phenylmethoxy)carbonyl]-N-[(l-methoxy-1-methYl)ethoxYlserinamide N-t(Phenylmethoxy)carbonyl]serine (47.8 g, 0.2 mol) was dissolved in 440 ml of dichloro-methane by the addition of triethylamine (20.2 g, 0.2 mol) and pyridine (2 g, 0.025 mol).
The mixture was cooled to -20C and pivaloyl chloride (24.2 g, 0.2 mol) was added dropwise within 20 minutes. After 15 minutes, stirring at ~26a~80 -20~C, [(l-methoxy-l-methyl)ethoxy]amine (25.2 g, 0.24 mol) was added at -20C. The mixture was stirred for 30 minutes at -20C and then added to a solution of sodium bicarbonate (30 g, 0.36 mol) in 300 ml of water. The temperature rose to 5C
and the pH was greater than 7.2. After 15 minutes, the organic layer was separated and the agueous layer was extracted with 50 ml of dichloro-methane. The solvent was removed in vacuo to a 10 50 ml volume, 400 ml of ethyl acetate was added and the solvent was removed again to a 100 ml volume. Addition of some seeds was followed by evaporating to a 50 ml volume. The resulting whi~e crystals were isolated by filtration and dried to afford 45.9 g of the title compound, melting point 96-98C.

B) (3S)-3-[[(Phenylmethoxy)carbonyl]amino]-l-hYdroxv-2-azetidinone N2-[(Phenylmethoxy)carbonyl]-N-[(1-methoxy-l-methyl)ethoxy]serinamide (32.6 g, 0.1 mol) was su~pended in 500 ml of ethyl acetate. After cooling to 0 to -5C, triethylamine (13.1 g, 0.13 mol) was added followed by dropwise addition 25 of methanesulfonyl chloride (14.7 g, 0.12 mol) within 15 minutes. The temperature did not exceed 0C. After l hour at 0C to -5C, the reaction was complete.
~ydrazine hydrate (3.3 ml) was added and the mixture was stirred for 30 minutes at 0C. The mixture was washed with 200 ml of water, two 180 ml portions of aqueous monobasic sodium phosphate solution (lOOg/l) and 80 ml of brine.
Potassium carbonate (40 g) was added to the solution of mesylated material in ethyl acetate ~Z68780 GC222 and the mixture was stirred overnight at 20C.
When the reaction had finished, it was filtered clear. water (16 ml) and 21 ml of methanol were added to the solution. The mixture was acidified to pH 1 with lN hydrochloric acid (ca. 25 ml), and about 40 ml of methanol was added to get a clear solution. After stirring for 4 hours at 20C, the reaction had finished. The mixture was washed twice with 100 ml of brine, then extracted with three 140 ml portions of aqueous potassium hydroxide (lOOg/l) at 20C. The aqueous layer was acidified with conc. hydrochloric acid (ca. 50 ml) to get a pH of 2.3 and stirred for 30 minutes.
The precipitate was filtered, washed with water and dried at 40C to afford 17.2 g of the title compound, melting point 122-123C, dec.

Exam~le 4 (3S-cls)-3-[[(Phenylmethoxy)carbonyl]amino]-l-[(1-methoxy-1-methyl)ethoxy]-4-methyl-2-azetidinone A) N2-~(Phenylmethoxy)carbonyl]-N-[(1-methoxy-l-methYljethoxv1allothreoninamide Following the procedure of example 2A, but substituting allothreonine for L-threonine, yielded the title compound.

B) (3S-cis)-3-[[(Phenylmethoxy)carbonyl]amino]-l-t(l-methoxy-1-methyl)ethoxy]-4-methyl-2-azetidinone N2-[(Phenylmethoxy)carbonyl]-N-[(1-methoxy-l-methyl)ethoxy]allothreoninamide (238.6 g, O.731 mol) was suspended in 2.5 1 of ethyl acetate. After cooling to -2C, triethylamine ~2~i~78~

(103.5 g, 1.022 mol) was added followed by the dropwise addition of methanesulfonyl chloride (117.2 g, 1.022 mol). After 1 hour at 0C, hydrazine hydrate (14.2 ml) was added and the mix~ure was stirred for 45 minutes at 0C. The mixture was washed with water, aqueous monobasic sodium phosphate solution (lOOg/l) and brine.
Potassium carbonate (292.5 g) was added to the solution and the mixture was stirred overnight at ambient temperature. After filtration~ 290 ml of water and 3~0 ml of methanol were added, and the mixture was adjusted to p~ 1 by adding 2N
hydrochloric acid. After stirring for two hours at ambient temperature, the mixture was washed with brine and water. Water ~800 ml) was added and the p~ was adjusted to 8.5 by the addition of an aqueous potassium hydroxide solution (lOOg/1).
The agueous solution was separated and adjusted to pH 2.5 by the addition of concentrated hydro-ch.loric acid. The precipitate was filtered off,washed with water and dried ~n vacuo, yielding 95.2 g of the title compound, melting point 133C.
.

Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are de-fined as follows:

1. A compound having the formula

2. The compound in accordance with claim 1, which is [(1-methoxy-1-methyl)ethoxy]amine.