Abstract
Nickel catalyst promotes the homoallylation of aldehydes and ketones with 1, 3-dienes in the presence of triethylborane and diethylzinc as reducing agents to provide bishomoallyl alcohols with high regio-and stereoselectivities. In place of diethylzinc, dimethylzinc serves as a methylating agent to evoke the three-component coupling reaction of methyl group, 1, 3-dienes, and carbonyls to provide 3-hexenols in excellent yields. Furthermore, nickel catalyzes the four-component connection reaction of carbonyls, 1, 3-dienes, alkynes, and dimethylzinc in this order to furnish 3, 6-octadien-1-ols.
A combination of palladium catalyst and triethylborane induces allylic alcohols to undergo the nucleophilic allylation of aromatic aldehydes to provide homoallyl alcohols. By the addition of lithium chloride and triethylamine to the Pd catalyst/triethylborane system, aliphatic aldehydes undergo the electrophilic allylation with allylic alcohols at the α-carbon of aldehydes to give α-allylated aldehydes. Under similar conditions, 2-methylenepropane-1, 3-diol can be utilized as a synthetic equivalent of a zwitterionic trimethylenemethane species to bring about the sequential amphiphilic allylation.
