A Ru-catalyzed tandem alkyne-enone coupling/Michael addition: synthesis of 4-methylene-2,6-cis-tetrahydropyrans.

[reaction: see text] A Ru-catalyzed tandem alkyne-enone coupling/Michael addition reaction is reported. It provides an efficient, atom-economic entry to 4-methylene-2,6-cis-tetrahydropyrans from simple, readily available homopropargylic alcohols and beta,gamma-unsaturated enones in good yields. Further functionalization of the resultant vinylsilane leads to the synthesis of either geometrically defined trisubstituted alkene exocyclic to the 2,6-cis-dihydropyran.