A highly enantio- and diastereoselective 1,3-dimethylallylation of aldehydes.

A highly enantio- and diastereoselective pentenylation of aldehydes is described. The homoallylic alcohol derived from 1,3-dimethylallylation of (-)-menthone undergoes an efficient allyl-transfer reaction with a wide range of aliphatic aldehydes in the presence of an acid catalyst to give rise to the corresponding 4-methyl-2(E)-penten-4-yl-5-ol products in good yields with high enantio- and 4,5-syn-selectivities.