Sc. Berk et al., DEVELOPMENT OF A TITANOCENE-CATALYZED ENYNE CYCLIZATION ISOCYANIDE INSERTION REACTION, Journal of the American Chemical Society, 116(19), 1994, pp. 8593-8601
The first early transition metal-catalyzed enyne cyclization reaction
is described. The system converts enyne substrates to bicyclic iminocy
clopentenes through the use of 10 mol % of Cp(2)Ti(PMe(3))(2) in the p
resence of a silyl cyanide. Subsequent hydrolysis produces the corresp
onding bicyclic cyclopentenones in good overall yield. The cyclization
reaction is tolerant of polar functional groups such as ethers, amine
s, and esters and is diastereoselective with certain chiral enyne subs
trates.