Recycling the tert-Butanesulfinyl Group in the Synthesis of AminesUsing tert-Butanesulfinamide

摘要

A practical process for recycling the tert-butanesulfinyl group upon deprotection of N-tert-butanesulfinylamines has been achieved. Treatment of N-tert-butanesulfinyl amines with HC1 in cyclopentyl methylether results in complete conversion to tert-butanesulfinyl chloride and the corresponding aminehydrochloride salt, which is isolated by filtration in analytically pure form and in quantitative yield.Treatment of the resulting sulfinyl chloride solution with aqueous ammonia then provides analyticallypure tert-butanesulfinamide in 97% yield. Alternatively, the tert-butanesulfinyl chloride solution can betreated with ethanol and catalytic quinidine as a sulfinyl transfer catalyst to provide a cyclopentyl methylether solution of ethyl tert-butanesulfinate with 88% ee. Addition of NaNH2 in ammonia followed bysimple trituration of the product with octane provides tert-butanesulfinamide with 99% ee and in 67%overall isolated yield based upon the starting N-tert-butanesulfinyl amine.