Polysubstituted enynes have been lithiated on the propargylic position, and transmetalation to the corresponding zinc reagents promotes an easy cyclization reaction leading to polysubstituted cyclopentylmethylzinc derivatives. This cyclization is stereospecific, and a single diastereoisomer is formed, even when a tertiary and a quaternary center are linked in the process. The reaction is considered to take place via a metallo-ene-allene process.
