Pyridine → 67838-56-6

Participants

Reaction Steps

The preparation of intermediate III is seen to involve the following steps: (1) the Grignard reaction of vinylmagnesium bromide with phenoxyacetaldehyde and subsequent acetylation of the complex to yield 4-benzyloxy-3-acetoxy-1-butene; (2) the free radical addition of thiolacetic acid to the double bond of the latter product to yield S-acetyl-3-acetoxy-4-benzyloxy-1-butanethiol; (3) the oxidation of the thiol with chlorine in aqueous acetic acid and reaction of the resulting sulfonyl chloride with ammonia to yield 4-benzyloxy-3-hydroxy-1-butanesulfonamide; (4) tosylation of this compound with p-toluenesulfonyl chloride in pyridine and ring closure with potassium carbonate in dimethylformamide; (5) hydrogenolysis of the protecting benzyl group over a palladium catalyst to yield 3-(hydroxymethyl)isothiazolidine 1,1-dioxide; and (6) alkylation of the latter compound with a lower alkyl ester of 7-bromo-5-heptynoic acid, preferably ethyl 7-bromo-5-heptynoate in dimethylformamide in the presence of potassium carbonate to yield intermediate III.

Provenance & Evidence