Transition-Metal-Mediated Cascade Reactions: The Water-Accelerated Carboalumination−Claisen Rearrangement−Carbonyl Addition Reaction

A three-step cascade reaction involving a water-accelerated catalytic carboalumination, a Claisen
rearrangement, and a nucleophilic carbonyl addition converts terminal alkynes and allyl vinyl ethers
into allylic alcohols containing up to three contiguous asymmetric carbon centers. Stoichiometric
quantities of water as an additive increase the rate of the [3,3] sigmatropic rearrangement as well
as the diastereoselectivity of the carbonyl addition process. Reaction products contain 1,6-diene
functionalities that are readily cyclized to substituted cyclopentenes. An extension of this
methodology to a sequence involving a [1,3] sigmatropic shift was feasible with a cyclopropylmethyl
vinyl ether substrate.