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 dlkynes 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. Not-ably, 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%.