Yttrocene-catalyzed asymmetric cyclization–hydrosilylation of α,ω-dienes

(R,S)-BnBpY-H (BnBp={(OC10H6C10H6O)Si(C5H2-2-SiMe3-4-CMe3)2}) is an effective catalyst for the cyclization–hydrosilylation of α,ω-dienes. The cyclization of 1,5-hexadienes and 1,6-heptadienes results in the formation of five- and six-membered rings, respectively, with low to moderate enantioselectivities. Deuterium labeling studies revealed that β-hydride elimination of the cycloalkylmethyl intermediate prior to σ-bond metathesis with the silane did not occur.