Silyl-cupration of an acetylene followed by ring-formation

Abstract

The acetylenes 1a–e undergo silyl-cupration followed by cyclisation, the acetylenes 1f–1h react with the silyl-cuprate reagent more rapidly at the alternative electrophilic site, and the acetylenes 1i, 1j and 17 give relatively low yields of cyclic products amongst others. Ring-formation is, unusually, a not particularly favourable pathway.