3-trimethylsilyl-1,3-oxazolidin-2-one

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The clear solution obtained after refluxing a mixture consisting of 40 ml of dichloromethane, 608.7 mg (1.75 mmoles) of 3-methyl-7-phenylacetamido-3-cephem-4-carboxylic acid-1-oxide and 450 mg (2.83 mmoles) of N-trimethylsilyl-2-oxazolidinone for two hours was cooled in an ice-bath and 0.1 g of amidosulfonic acid (1 mmole) was added thereto. Bromination was carried out in half an hour using 469 mg (2.63 mmoles) of N-bromosuccinimide as the brominating agent to obtain a 46% yield of trimethylsilyl 3-bromomethyl-7-phenylacetamido-3-cephem-4-carboxylate-1-oxide. The clear solution obtained after refluxing a mixture was cooled in an ice-bath Bromination was carried out in half an hour

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture consisting of 753 mg (2.16 mmoles) of 3-methyl-7-phenylacetamido-3-cephem-4-carboxylic acid-1-oxide, 785 mg (4.94 mmoles) of N-trimethylsilyl-2-oxazolidinone and 70 ml of dichloromethane was refluxed for 2 hours, after which a clear, almost colorless solution was obtained. This was cooled in an ice-bath and bromination was carried out in half an hour using 624.5 mg (3.51 mmoles) of N-bromosuccinimide as the brominating agent to obtain a yield of 48% of trimethylsilyl 3-bromomethyl-7-phenylacetamido-3-cephem-4-carboxylate-1-oxide. was refluxed for 2 hours after which a clear, almost colorless solution was obtained This was cooled in an ice-bath bromination was carried out in half an hour

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To the above solution, there were added 0.28 mole of 3-trimethylsilyl-2-oxazolidinone (TMSO, 38.2 ml) and 0.02 mole of triethylamine p-toluenesulphonate (8.468 g). After stirring for 15 minutes, the mixture was heated under reflux for 120 minutes. Thereafter 0.1 mole of dimethylaniline p-toluene sulphonate (29.3 g) and 0.12 mole of thiourea (9.13 g) were added and heating was maintained for a further 60 minutes. Thereafter the mixture was concentrated at reduced pressure and water (100 ml) was added to the residue. The pH was adjusted to 8.5 in the presence of methylene chloride, the phenyl-pseudothio-hydantoin was filtered out and the water phase was decanted off. After further adjustment To pH 4.2, the mixture was filtered again to give 7-ADCA (14.9 g) with 70% yield. Identified by its IR spectrum, m.p. 232- 42 (d) and [α] D2 = 105.0° (C = 1%, 0.5 N HCL). the mixture was heated under reflux for 120 minutes heating was maintained for a further 60 minutes Thereafter the mixture was concentrated at reduced pressure and water (100 ml) was added to the residue the phenyl-pseudothio-hydantoin was filtered out the water phase was decanted off After further adjustment To pH 4.2, the mixture was filtered again