Nickel-Catalyzed Homoallylation of Aldehydes in the Presence of Water and Alcohols We thank Mr. Y. Ohhama, NMR Facility, for his outstanding technical assistance. Financial support from the Ministry of Education, Science, Sports, and Culture, Japanese Government, Grant-in-Aid for Scientific Research B, is acknowledged.

Bishomoallyl alcohols are obtained with excellent 1,2- and 1,3-asymmetric induction from reactions of unsymmetrical dienes with glutaraldehyde (50 % aqueous) or cyclic hemiacetals at room temperature see for example, Eq. (1). These homoallylations of aldehydes in the presence of water are promoted by the catalytic system Ni(acac)2/Et3B (acac=acetylacetone).