Pyrolysis of (R)-(-)-(E)-1, 4-diphenyl-3-penten-l-ol (3) at 460 “C leads to benzaldehyde and (R)-(-)-3-phenyl-1-butene, formed in 25.6% enantiomeric excess. While the results support a concerted cyclic reaction, the direction of asymmetric induction is not that expected on the basis of a transition state conformation resembling chair cyclo-hexane. It is concluded that the chair model is a poor one for thermal reactions involving hydrogen transfer.
