Conjugate addition of lithium phenylthio- and cyano-[2-(4-chlorobut-1-enyl)]cuprate to cyclic enones. An efficient methylenecyclopentane annulation process

Reaction of the cyclic enones (6)–(11) with the structurally interesting cuprate reagent (2) and (3) provides very good yields of the conjugate addition products (12)–(17); treatment of the latter substancesh with potassium hydride in tetrahydrofuran affords the methylenecyclopentane annulation products (18)–(23), respectively.