Wittig olefination and thiol mediated 7-endo-trig radical cyclization: novel synthesis of oxepin derivatives
作者:K.C. Majumdar、Abu Taher
DOI:10.1016/j.tetlet.2008.10.134
日期:2009.1
Thiophenol-mediated 7-endo radical cyclization for the synthesis of seven-membered cyclic ethers is described. This method can be successfully applied to synthesize various benzoxepin derivatives, which are present in many natural products as building blocks. Alkenyl radicals are generated from easily available terminal alkynes and thiophenol.
[GRAPHICS]The Pauson-Khand reaction still has a relatively low scope with respect to the used carbon skeleton, while yields are low in many other cases. We have observed that the addition of molecular sieves improves yields remarkably, Experimental protocol is extremely easy, and it has been applied to several substrates including the less favorable ones.