tert-butyl 2,3-dibromopropanoate

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

Procedure: Preferably, t-butyl 2,3-dibromopropionate prepared according to J. Perkin Trans I, p. 1321 (1973) is treated with 2-mercaptoethylamine and triethylamine in a suitable solvent, such as a mixture of chloroform and benzene, to provide t-butyl tetrahydro-2H-1,4-thiazine-3-carboxylate, which upon reaction with a compound of the formula V under suitable conditions, such as in the presence of triethylamine in dichloromethane solution at 25° C., provides compounds of the formula II-c. Oxidation of this material with a suitable oxidizer, such as sodium perborate or m-chloroperbenzoic acid, provides the corresponding sulfoxide, preferably as a single diastereomer.