64485-82-1

Basic information

• Product Name: Ethyl 2-(2-aminothiazole-4-yl)-2-hydroxyiminoacetate
• Synonyms: Ethyl 2-amino-α-(hydroxyimino)-4-thiazoleacetate, predominantly syn;Ethyl (2Z)-2-(2-amino-1,3-thiazol-4-yl)-2-hydroxyiminoacetate;Ethyl 2-(2-Aminothiazol-4-yl)-2-hydroxyimino acetate ,98%;ETHYL 2-(2-AMINOTHIAZOL-4-YL)-2-HYDROXYIMINOACETATE, 97%, PREDOMINANTLY SYN, PURE;(2-Aminothiazol-4-yl)[(Z)-hydroxyimino]acetic acid ethyl ester;Ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate,97%,pure,predominantly syn;Ethyl 2-amino-α-(hydroxyimino)-4-thiazoleacetate;2-(2-AMinothiazole-4-yl)-2-hydroxyiMinoacetate
• CAS NO: 64485-82-1
• Molecular Formula: C₇H₉N₃O₃S
• Molecular Weight: 215.23
• EINECS: 264-910-1
• Product Categories: Building Blocks;Heterocyclic Building Blocks;Thiazoles;Intermediates;Intermediates & Fine Chemicals;Pharmaceuticals;Sulfur & Selenium Compounds;Pharmaceutical Intermediates;Cephalosporins
• Mol File: 64485-82-1.mol
• Article Data: 7

Chemical Properties

• Melting Point: 195-197 °C(lit.)
• Boiling Point: 426.8 °C at 760 mmHg
• Flash Point: 211.9 °C
• Appearance: light yellow to beige fine powder
• Density: 1.4565 (rough estimate)
• Vapor Pressure: 4.8E-08mmHg at 25°C
• Refractive Index: 1.6630 (estimate)
• Storage Temp.: -20?C Freezer, Under Inert Atmosphere
• Solubility: DMSO (Slightly), Methanol (Slightly)
• PKA: 9.53±0.70(Predicted)
• CAS DataBase Reference: Ethyl 2-(2-aminothiazole-4-yl)-2-hydroxyiminoacetate(CAS DataBase Reference)
• NIST Chemistry Reference: Ethyl 2-(2-aminothiazole-4-yl)-2-hydroxyiminoacetate(64485-82-1)
• EPA Substance Registry System: Ethyl 2-(2-aminothiazole-4-yl)-2-hydroxyiminoacetate(64485-82-1)

Safety Data

• Hazard Codes: Xi
• Statements: 36/37/38
• Safety Statements: 26-37/39-24/25
• WGK Germany: 3
• Hazardous Substances Data: 64485-82-1(Hazardous Substances Data)

Usage

Uses

Ethyl 2-amino-α-(hydroxyimino)-4-thiazoleacetate may be used in chemical synthesis.

InChI:InChI=1/C7H9N3O3S/c1-2-13-6(11)5(10-12)4-3-14-7(8)9-4/h3,12H,2H2,1H3,(H2,8,9)/b10-5-

Synthetic route

thiourea (17356-08-0) + ethyl 4-chloro-2-hydroxyimino-3-oxo-butyrate (66338-95-2) → (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1)

Conditions	Yield
In ethanol; water at 20℃; for 1h;
In N,N-dimethyl acetamide at 20℃; for 3h;	8.9 g

ethyl 2-(hydroxyimino)-3-oxybutyrate (66508-93-8) → (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1)

Conditions	Yield
Multi-step reaction with 2 steps 1: SO2Cl2; glac. AcOH / 1 h / 58 - 60 °C 2: 8.9 g / N,N-dimethyl-acetamide / 3 h / 20 °C View Scheme
With sulfuryl dichloride; thiourea; 2,3-Dimethylaniline In diethyl ether; ethanol; dichloromethane

ethyl acetoacetate (141-97-9) + 3,7,8,8-tetramethyl-non-6ξ-en-1-yn-3-ol → (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1)

Conditions	Yield
Multi-step reaction with 3 steps 1: aq. NaNO2; glac. AcOH / 0.5 h / 10 °C 2: SO2Cl2; glac. AcOH / 1 h / 58 - 60 °C 3: 8.9 g / N,N-dimethyl-acetamide / 3 h / 20 °C View Scheme

ethyl acetoacetate (141-97-9) → (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1)

Conditions	Yield
Multi-step reaction with 2 steps 1.1: sodium nitrite; acetic acid / water / 3.7 h / 20 °C 2.1: sulfuric acid / water; methanol; ethanol / 15 - 20 °C 2.2: 3407 / 2.5 h / 20 - 28 °C View Scheme

ethyl 2-(hydroxyimino)-3-oxybutyrate (66508-93-8) + thiourea (17356-08-0) → (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1)

Conditions	Yield
Stage #1: ethyl 2-(hydroxyimino)-3-oxybutyrate With sulfuric acid In methanol; ethanol; water at 15 - 20℃; Stage #2: thiourea With tetrabutylammomium bromide; potassium carbonate In methanol at 20 - 28℃; for 2.5h;

trityl chloride (76-83-5) + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → ethyl 2-(2-tritylaminothiazol-4-yl)-(Z)-2-(tritylhydroxyimino)acetate (69689-86-7)

Conditions	Yield
Stage #1: (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate With triethylamine In acetonitrile at 20 - 25℃; for 0.166667h; Stage #2: trityl chloride In acetonitrile at 55 - 60℃; for 1h;	99.2%
With triethylamine In N,N-dimethyl-formamide at 50℃;	85%
With triethylamine In N,N-dimethyl-formamide at 50℃;	85%

sodium hydrogencarbonate (144-55-8) + 3-bromopropylamine tert-butylcarbamate (83948-53-2) + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → ethyl (2Z)-2-(2-aminothiazol-4-yl)-2-(3-N-tert-butoxycarbonylaminopropoxyimino)acetate

Conditions	Yield
With potassium carbonate In water; ethyl acetate; N,N-dimethyl-formamide	96%
With potassium carbonate In water; ethyl acetate; N,N-dimethyl-formamide	96%

triphenylmethyl alcohol (76-84-6) + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → ethyl (2-aminothiazol-4-yl)-2-(Z)-(trityloxyimino)acetate (128438-00-6)

Conditions	Yield
Stage #1: triphenylmethyl alcohol; (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate With boron trifluoride diethyl etherate; acetic acid In water; ethyl acetate at -5 - 45℃; for 25.5h; Inert atmosphere; Stage #2: With sodium hydrogencarbonate In water	92%

chloroacetyl chloride (79-04-9) + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → 4-<(Z)-1-Carbethoxy-1-hydroxyimino>methyl-2-chloroacetamidothiazole (94418-08-3)

Conditions	Yield
In N,N-dimethyl acetamide 1) 30 min., 0 deg C, 2) 30 min., room temper.;	88%

Cyclopentyl bromide (137-43-9) + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → ethyl (Z)-2-(2-aminothiazol-4-yl)-2-(cyclopentyloxyimino)acetate (74439-94-4)

Conditions	Yield
With potassium carbonate In dimethyl sulfoxide at 50℃; for 20h;	81%

benzimidazo[2,1-a]benz[de]isoquinoline-7-one-12-carboxylic acyl chloride + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → ethyl (Z)-2-(hydroxyimino)-2-(2-(benzimidazo[2,1-α]benz[de]isoquinoline-7-one-12-carboxamido)thiazol-4-yl)acetate

Conditions	Yield
In chloroform; N,N-dimethyl-formamide at 20℃; for 0.5h;	21%

trityl chloride (76-83-5) + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → ethyl (Z)-2-hydroxyimino-2-(2-triphenylmethylaminothiazol-4-yl)acetate (66338-99-6)

Conditions	Yield
With triethylamine In N,N-dimethyl-formamide for 1h;
With triethylamine In N,N-dimethyl-formamide at 20℃;

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → 2-(2-Amino-1,3-thiazol-4-yl)-2-(hydroxyimino)acetic acid (66338-96-3)

Conditions	Yield
With sodium hydroxide In ethanol at 45℃; for 0.5h;
With sodium hydroxide In ethanol
With sodium hydroxide In ethanol

N,N-dimethyl acetamide (127-19-5) + trityl chloride (76-83-5) + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → (Z)-(2-aminothiazol-4-yl)-2-trityloxyiminoacetic acid N,N-dimethylacetamide solvate

Conditions	Yield
Yield given. Multistep reaction;

trityl chloride (76-83-5) + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → ethyl 2-(2-tritylaminothiazol-4-yl)-(Z)-2-(tritylhydroxyimino)acetate (69689-86-7) + ethyl (2-aminothiazol-4-yl)-2-(Z)-(trityloxyimino)acetate (128438-00-6)

Conditions	Yield
With potassium tert-butylate In tetrahydrofuran 1.) r.t., 2 h, 2.) 40 deg C, 4 h; Yield given. Yields of byproduct given. Title compound not separated from byproducts;

trityl chloride (76-83-5) + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → (Z)-2-(2-aminothiazol-4-yl)-2-(triphenylmethoxyimino)acetic acid (128438-01-7) + (Z)-2-(trityloxyimino)-2-(2-tritylamino-4-thiazolyl)acetic acid (68786-47-0)

Conditions	Yield
With potassium tert-butylate 1.) THF, r.t., 2 h; 40 deg C, 4 h, 2.) EtOH, reflux, 4 h; Multistep reaction. Yields of byproduct given. Title compound not separated from byproducts;
With potassium tert-butylate 1.) THF, r.t., 2 h; 40 deg C, 4 h, 2.) EtOH, reflux, 4 h; Yield given. Multistep reaction. Title compound not separated from byproducts;

trityl chloride (76-83-5) + (Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → ethyl (2-aminothiazol-4-yl)-2-(Z)-(trityloxyimino)acetate (128438-00-6)

Conditions	Yield
With potassium tert-butylate In tetrahydrofuran
In tetrahydrofuran; chloroform; mineral oil

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → cefdinir (91832-40-5)

Conditions	Yield
Multi-step reaction with 5 steps 1: 52.2 percent / TEA / CHCl3 / 1.5 h / 20 °C 2: 97.6 percent / aq. NaOH / dioxane / 2 h / 100 - 110 °C 3: 92.4 percent / N,N-dimethylaniline; POCl3 / CH2Cl2 / 1.5 h / -15 - -10 °C 4: TFA; anisole / CH2Cl2 / 0 - 5 °C 5: 2.54 g / aq. HCOOH / 3 h / 20 °C View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → 7β-[(Z)-2-(2-amino-4-thiazolyl)-2-(trityloxyamino)acetamido]-3-vinylcephem-4-carboxylic acid (128454-32-0)

Conditions	Yield
Multi-step reaction with 4 steps 1: 52.2 percent / TEA / CHCl3 / 1.5 h / 20 °C 2: 97.6 percent / aq. NaOH / dioxane / 2 h / 100 - 110 °C 3: 92.4 percent / N,N-dimethylaniline; POCl3 / CH2Cl2 / 1.5 h / -15 - -10 °C 4: TFA; anisole / CH2Cl2 / 0 - 5 °C View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → sodium 2-(2-tritylaminothiazol-4-yl)-(Z)-2-(tritylhydroxyimino)acetate

Conditions	Yield
Multi-step reaction with 2 steps 1: 52.2 percent / TEA / CHCl3 / 1.5 h / 20 °C 2: 97.6 percent / aq. NaOH / dioxane / 2 h / 100 - 110 °C View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → diphenylmethyl 7β-[2-(2-tritylaminothiazol-4-yl)-(Z)-2-tritylhydroxyimino]-3-vinyl-3-cephem-4-carboxylate (123201-39-8)

Conditions	Yield
Multi-step reaction with 3 steps 1: 52.2 percent / TEA / CHCl3 / 1.5 h / 20 °C 2: 97.6 percent / aq. NaOH / dioxane / 2 h / 100 - 110 °C 3: 92.4 percent / N,N-dimethylaniline; POCl3 / CH2Cl2 / 1.5 h / -15 - -10 °C View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → (Z)-2-(2-aminothiazol-4-yl)-2-(triphenylmethoxyimino)acetic acid (128438-01-7)

Conditions	Yield
Multi-step reaction with 2 steps 1: T-BuOK / tetrahydrofuran 2: KOH / ethanol / Saponification View Scheme
Multi-step reaction with 2 steps 1.1: boron trifluoride diethyl etherate / acetic acid / ethyl acetate; water / 25.5 h / -5 - 45 °C / Inert atmosphere 2.1: potassium hydroxide; water / ethanol / 20 - 30 °C / Reflux 2.2: pH 4 - 5 View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → (Z)-2-(2-amino-5-chlorothiazol-4-yl)-2-(triphenylmethoxyimino)acetic acid (189449-52-3)

Conditions	Yield
Multi-step reaction with 3 steps 1: T-BuOK / tetrahydrofuran 2: KOH / ethanol / Saponification 3: 71 percent / N-chlorosuccinimide / dimethylformamide / 20 °C View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → MC-02,479

Conditions

Yield

Multi-step reaction with 7 steps 1.1: T-BuOK / tetrahydrofuran 2.1: KOH / ethanol / Saponification 3.1: 71 percent / N-chlorosuccinimide / dimethylformamide / 20 °C 4.1: 65 percent / pyridine; POCl3 / tetrahydrofuran / 0.5 h / cooling 5.1: 95 percent / sodium hydrogen sulfide hydrate / dimethylformamide / 0.25 h / -20 °C 6.1: 26 percent / dimethylformamide / 20 °C 7.1: trifluoroacetic acid / CH2Cl2 / 1.5 h 7.2: formic acid / H2O / 4 h / 20 °C View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → (7R)-7-[(Z)-2-(2-amino-5-chlorothiazol-4-yl)-2-(triphenylmethoxyimino)acetamido]-3-chloro-3-cephem-4-carboxylate diphenylmethyl ester (189449-54-5)

Conditions	Yield
Multi-step reaction with 4 steps 1: T-BuOK / tetrahydrofuran 2: KOH / ethanol / Saponification 3: 71 percent / N-chlorosuccinimide / dimethylformamide / 20 °C 4: 65 percent / pyridine; POCl3 / tetrahydrofuran / 0.5 h / cooling View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → (7R)-7-[(Z)-2-(2-amino-5-chlorothiazol-4-yl)-2-(triphenylmethoxyimino)acetamido]-3-mercapto-3-cephem-4-carboxylate diphenylmethyl ester (189449-55-6)

Conditions	Yield
Multi-step reaction with 5 steps 1: T-BuOK / tetrahydrofuran 2: KOH / ethanol / Saponification 3: 71 percent / N-chlorosuccinimide / dimethylformamide / 20 °C 4: 65 percent / pyridine; POCl3 / tetrahydrofuran / 0.5 h / cooling 5: 95 percent / sodium hydrogen sulfide hydrate / dimethylformamide / 0.25 h / -20 °C View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → (7R)-7-[(Z)-2-(2-amino-5-chlorothiazol-4-yl)-2-(triphenylmethoxyimino)acetamido]-3-[3-(N-tert-butoxycarbonylaminoethylthiomethyl)pyrid-4-ylthio]-3-cephem-4-carboxylate diphenylmethyl ester (189449-58-9)

Conditions	Yield
Multi-step reaction with 6 steps 1: T-BuOK / tetrahydrofuran 2: KOH / ethanol / Saponification 3: 71 percent / N-chlorosuccinimide / dimethylformamide / 20 °C 4: 65 percent / pyridine; POCl3 / tetrahydrofuran / 0.5 h / cooling 5: 95 percent / sodium hydrogen sulfide hydrate / dimethylformamide / 0.25 h / -20 °C 6: 26 percent / dimethylformamide / 20 °C View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → S-(2-benzothiazolyl) 2-(2-aminothiazol-4-yl)-2(Z)-trityloxyiminothioacetate (143183-03-3)

Conditions	Yield
Multi-step reaction with 2 steps 2: 1.) Ph3P / 1.) CH2Cl2, r.t., 40 min, 2.) r.t., 1.5 h View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → (6R,7R)-7-{2-(2-Amino-thiazol-4-yl)-2-[(Z)-trityloxyimino]-acetylamino}-3-methoxymethyl-8-oxo-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid (S)-1-(2,2-dimethyl-propionyloxy)-ethyl ester (152401-10-0)

Conditions	Yield
Multi-step reaction with 3 steps 2: 1.) Ph3P / 1.) CH2Cl2, r.t., 40 min, 2.) r.t., 1.5 h 3: dimethylformamide; propan-1-ol / 2 h / Ambient temperature View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → (6R,7R)-7-{2-(2-Amino-thiazol-4-yl)-2-[(Z)-hydroxyimino]-acetylamino}-3-methoxymethyl-8-oxo-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylic acid (S)-1-(2,2-dimethyl-propionyloxy)-ethyl ester; compound with toluene-4-sulfonic acid

Conditions	Yield
Multi-step reaction with 4 steps 2: 1.) Ph3P / 1.) CH2Cl2, r.t., 40 min, 2.) r.t., 1.5 h 3: dimethylformamide; propan-1-ol / 2 h / Ambient temperature 4: 86 percent / propan-1-ol / 1.5 h / 80 °C View Scheme

(Z)-ethyl 2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetate (64485-82-1) → (Z)-2-(2-aminothiazol-4-yl)-2-(cyclopentyloxyimino)acetic acid (74439-96-6)

Conditions	Yield
Multi-step reaction with 2 steps 1: 81 percent / potassium carbonate / dimethylsulfoxide / 20 h / 50 °C 2: 80 percent / aq. NaOH / H2O; ethanol / 16 h / Ambient temperature View Scheme

Upstream product

• 17356-08-0 thiourea 
• 66338-95-2 ethyl 4-chloro-2-hydroxyimino-3-oxo-butyrate 
• 66508-93-8 ethyl 2-(hydroxyimino)-3-oxybutyrate 
• 141-97-9 ethyl acetoacetate 

Downstream Products

• 69689-86-7 ethyl 2-(2-tritylaminothiazol-4-yl)-(Z)-2-(tritylhydroxyimino)acetate 
• 66338-99-6 ethyl (Z)-2-hydroxyimino-2-(2-triphenylmethylaminothiazol-4-yl)acetate 
• 66338-96-3 2-(2-Amino-1,3-thiazol-4-yl)-2-(hydroxyimino)acetic acid 
• 128438-00-6 ethyl (2-aminothiazol-4-yl)-2-(Z)-(trityloxyimino)acetate 
• 128438-01-7 (Z)-2-(2-aminothiazol-4-yl)-2-(triphenylmethoxyimino)acetic acid 
• 68786-47-0 (Z)-2-(trityloxyimino)-2-(2-tritylamino-4-thiazolyl)acetic acid 
• 91832-40-5 cefdinir 
• 128454-32-0 7β-[(Z)-2-(2-amino-4-thiazolyl)-2-(trityloxyamino)acetamido]-3-vinylcephem-4-carboxylic acid 
• 123201-39-8 diphenylmethyl 7β-[2-(2-tritylaminothiazol-4-yl)-(Z)-2-tritylhydroxyimino]-3-vinyl-3-cephem-4-carboxylate 
• 189449-52-3 (Z)-2-(2-amino-5-chlorothiazol-4-yl)-2-(triphenylmethoxyimino)acetic acid 
• 189449-54-5 (7R)-7-[(Z)-2-(2-amino-5-chlorothiazol-4-yl)-2-(triphenylmethoxyimino)acetamido]-3-chloro-3-cephem-4-carboxylate diphenylmethyl ester 
• 189449-55-6 (7R)-7-[(Z)-2-(2-amino-5-chlorothiazol-4-yl)-2-(triphenylmethoxyimino)acetamido]-3-mercapto-3-cephem-4-carboxylate diphenylmethyl ester 
• 189449-58-9 (7R)-7-[(Z)-2-(2-amino-5-chlorothiazol-4-yl)-2-(triphenylmethoxyimino)acetamido]-3-[3-(N-tert-butoxycarbonylaminoethylthiomethyl)pyrid-4-ylthio]-3-cephem-4-carboxylate diphenylmethyl ester 
• 143183-03-3 S-(2-benzothiazolyl) 2-(2-aminothiazol-4-yl)-2(Z)-trityloxyiminothioacetate 

Relevant articles and documents

Synthetic method for ceftazidime side chain acid ethyl ester

The invention belongs to the technical field of medicine, and particularly relates to a synthetic method for ceftazidime side chain acid ethyl ester. The method comprises the following steps: adding sodium nitrite and ethyl acetoacetate into water, adding acetic acid for a reaction, performing extraction, and collecting the organic phase; performing distillation on the collected organic phase under normal and reduced pressure to obtain an oxime compound, performing dehydration treatment on the oxime compound, adding an alcohol, a catalyst and chlorine gas, and performing a chlorination reaction to obtain a chloride; performing a reaction on methanol, thiourea, a phase transfer catalyst, a buffer salt solution and the chloride to obtain an ethyl 2-(2-aminothiazole-4-yl)-2-hydroxyiminoacetate solution; and performing distillation on the ethyl 2-(2-aminothiazole-4-yl)-2-hydroxyiminoacetate solution under reduced pressure to obtain ethyl 2-(2-aminothiazole-4-yl)-2-hydroxyiminoacetate solution and a buffer salt, adding tert-butyl 2-bromoisobutyrate, a condensation catalyst and a solvent, and performing a reaction to obtain the ceftazidime side chain acid ethyl ester. The method is moreefficient, simpler, and more environmentally friendly and has higher quality and yield than a previous processes, and is suitable for large-scale industrial production.

7-[2-(2-Aminothiazol-4-yl)-2-(syn)-methoxyiminoacetamido] cephalosporins

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Cephalosporin antibiotics of the general formula STR1 (wherein Ra and Rb, which may be the same or different, each represent a C1-4 alkyl group or Ra and Rb together with the carbon atom to which they are attached form a C3-7 cycloalkylidene group; and R4 represents hydrogen or a 3- or 4-carbamoyl group) exhibit broad spectrum antibiotic activity, the activity being unusually high against gram-negative organisms such as strains of Pseudomonas organisms. A particular antibiotic compound of formula (I) possessing excellent antibacterial activity against strains of Pseudomonas organisms, as well as other valuable therapeutic properties, is (6R,7R)-7-[(Z)-2-(2-aminothiazol-4-yl)-2-(2-carboxyprop-2-oxyimono) acetamido]-3-(1-pyridiniummethyl)-ceph-3-em-4 carboxylate. The invention also includes the non-toxic salts and non-toxic metabolically labile esters of compounds of formula (I). Also described are compositions containing the antibiotics of the invention and processes for the preparation of such antibiotics.