1-bromoethyl ethyl carbonate

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: A mixture of diethyl carbonate (35 g, 0.3 m) in carbon tetrachloride (50 ml) and alpha-azo-isobutyronitrile (AIBN) (0.1 g) was heated to gentle reflux and dibromodimethyl hydantoin (28.6 g, 0.1 m) was added in small aliquots over a period of 8 hours together with further additions of AIBN (8×0.05 g): care being taken to ensure that free bromine did not accumulate in the reaction mixture. At the end of the reaction the mixture was subjected to vacuum fractional distillation to afford pure ethyl alpha-bromoethyl carbonate (32.3 g, 82% yield) identical in all respects with the product of Examples 3 and 4. was heated to gentle reflux At the end of the reaction the mixture was subjected to vacuum fractional distillation

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

Procedure: Lithium bromide (17.4 g, 0.2 m) was dissolved in dimethy formamide (150 ml) and the mixture cooled to ambient temperature. Ethyl alpha-chloroethyl carbonate (30.5 g, 0.2 m) was added and the mixture stirred at ambient temperature for 24 hours. The precipitated lithium chloride was filtered off and the filtrate vacuum distilled to afford after careful re-fractionation, ethyl alpha-bromoethyl carbonate in 76% yield based upon recovered ethyl alphachloroethyl carbonate. The precipitated lithium chloride was filtered off the filtrate vacuum distilled

Conditions: temp:35.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of lithium bromide (43 g, 0.5 m), ethyl alphachloroethyl carbonate (15.3 g, 0.1 m); water (100 ml), dichloromethane (100 ml) and cetyl trimethyl ammonium bromide (1.5 g) was stirred at ambient temperature for 24 hours. The aqueous layer was removed and replaced by a fresh solution of lithium bromide (26 g, 0.3 m) in water (40 ml) containing cetyl trimethyl ammonium bromide (1 g). After stirring for a further 24 hours during which time the temperature was raised to 35° C., the organic layer was separated, dried and vacuum distilled to afford after repeated fractionation the new compound, ethyl alpha-bromoethyl carbonate (15.0 g, 76% yield) having a boiling point of 90°-92° C. at 35 mms of mercury pressure. The aqueous layer was removed containing cetyl trimethyl ammonium bromide (1 g) the organic layer was separated dried vacuum distilled to afford

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: (6R,7R)-3-Carbamoyloxymethyl-7-[(Z)-2-cyclopropylmethoxyimino-2-(2-tritylaminothiazol-4-yl)acetamido]ceph-3-em-4-carboxylic acid (1.1 g) was dissolved in N,N-dimethylformamide (5 ml) and stirred with potassium carbonate (105 mg) under nitrogen with ice-water cooling. After 10 minutes, 1-ethoxycarbonyloxy-1-ethyl bromide was added. After one hour, the mixtured was allowed to attain 21° and was stirred thus for three hours. The mixture was partitioned between ethyl acetate and aqueous hydrochloric acid. The aqueous layer was extracted with more ethyl acetate and the combined organic layers were washed twice with brine, dried with magnesium sulphate and concentrated. The residue was chromatographed on Sorbsil U30 (50 g) in ethyl acetate (10 to 60%) in petroleum ether (bp 40° to 60°) to give the title compound (930 mg); [α]D21 +44.0° (c 1.30, CHCl3); λmax (ethanol) 230 nm (E1 cm1% 312), λ infl 236 nm (ED1% 295) and λnm (E1 cm1% 226). After one hour to attain 21° The mixture was partitioned between ethyl acetate and aqueous hydrochloric acid The aqueous layer was extracted with more ethyl acetate the combined organic layers were washed twice with brine dried with magnesium sulphate concentrated The residue was chromatographed on Sorbsil U30 (50 g) in ethyl acetate (10 to 60%) in petroleum ether (bp 40° to 60°)

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

Procedure: A mixture of diethyl carbonate (35 g, 0.3 m) in carbon tetrachloride (50 ml) and alpha-azo-isobutyronitrile (AIBN) (0.1 g) was heated to gentle reflux and dibromodimethyl hydantoin (28.6 g, 0.1 m) was added in small aliquots over a period of 8 hours together with further additions of AIBN (8×0.05 g): care being taken to ensure that free bromine did not accumulate in the reaction mixture. At the end of the reaction the mixture was subjected to vacuum fractional distillation to afford pure ethyl alpha-bromoethyl carbonate (32.3 g, 82% yield) identical in all respects with the product of Examples 3 and 4. was heated to gentle reflux At the end of the reaction the mixture was subjected to vacuum fractional distillation

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

Procedure: Lithium bromide (17.4 g, 0.2 m) was dissolved in dimethyl formamide (150 ml) and the mixture cooled to ambient temperature. Ethyl alphachloroethyl carbonate (30.5 g, 0.2 m) was added and the mixture stirred at ambient temperature for 24 hours. The precipitated lithium chloride was filtered off and the filtrate vacuum distilled to afford after careful re-fractionation, ethyl alpha-bromoethyl carbonate in 76% yield based upon recovered ethyl alphachloroethyl carbonate. The precipitated lithium chloride was filtered off the filtrate vacuum distilled

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

Procedure: Lithium bromide (17.4 g, 0.2 m) was dissolved in dimethyl formamide (150 ml) and the mixture cooled to ambient temperature. Ethyl alphachloroethyl carbonate (30.5 g, 0.2 m) was added and the mixture stirred at ambient temperature for 24 hours. The precipitated lithium chloride was filtered off and the filtrate vacuum distilled to afford after careful re-fractionation, ethyl alpha-bromoethyl carbonate in 76% yield based upon recovered ethyl alphachloroethyl carbonate. The precipitated lithium chloride was filtered off the filtrate vacuum distilled