Addition of acyl and sulfonyl hypohalites generated from N-halogeno amides to alkenes: synthesis of trans-vic-halogeno esters and their conversion to cis-1,2-diols

Abstract

N-lodo- and N-bromo-p-nitrobenzamide have been shown to react with various organic acids to form the respective acyl or sulfonyl hypoiodites or hypobromites. These readily add to double bonds under mild conditions to yield trans-vic-halogeno esters. The stereochemistry, as well as the regioselectivity, of these additions have been rationalised in terms of an intermediate iodonium or bromonium ion. Alkaline hydrolysis of adducts from cyclohexene gave good yields of ciscyclohexane-1, 2-diols, suggesting this methodology to be a viable alternative to the Woodward–Prevost synthesis of cis-1, 2-diols.