One-Pot Ring-Closing Metathesis-Alkene Cross Metathesis Reactions of Sulfamide-Linked Enynes

Ring‐closing metathesis (RCM) of sulfamide‐linked enynes 7, 11 and 12 containing disubstituted alkynes afforded a series of novel 7‐membered cyclic sulfamides 13−15 in good yield. Substrates 5, 9 and 10 containing mono‐substituted alkynes gave either simple RCM products 18a−c or those arising from combinations of enyne RCM and olefin cross metathesis 16/17a−c depending on the reaction conditions. Notably, in the presence of two equivalents of styrene or ethyl acrylate, substrates 5, 9 and 10 containing terminal alkynes underwent selective enyne‐RCM‐olefin‐cross metathesis to provide cyclic sulfamides 17a−c and 19b,c in yields of 54−83%. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)