| Abstract
| - A one-pot method for the direct preparation of enantioenriched (Z)-disubstituted allylic alcoholsis introduced. Hydroboration of 1-halo-1-alkynes with dicyclohexylborane, reaction with t-BuLi, andtransmetalation with dialkylzinc reagents generate (Z)-disubstituted vinylzinc intermediates. In situ reactionof these reagents with aldehydes in the presence of a catalyst derived from (−)-MIB generates(Z)-disubstituted allylic alcohols. It was found that the resulting allylic alcohols were racemic, most likelydue to a rapid addition reaction promoted by LiX (X = Br and Cl). To suppress the LiX-promoted reaction,a series of inhibitors were screened. It was found that 20−30 mol % tetraethylethylenediamine inhibitedLiCl without inhibiting the chiral zinc-based Lewis acid. In this fashion, (Z)-disubstituted allylic alcoholswere obtained with up to 98% ee. The asymmetric (Z)-vinylation could be coupled with tandemdiastereoselective epoxidation reactions to provide epoxy alcohols and allylic epoxy alcohols with up tothree contiguous stereogenic centers, enabling the rapid construction of complex building blocks with highlevels of enantio- and diastereoselectivity.
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