Allylation

A secondary homoallylic alcohol is created by the enantioselective, iridium-catalyzed addition of an allyl group to an aldehyde or an alcohol. When employing aldehyde reactants, the Krische allylation's method requires hydrogen transfer from 2-propanol or primary alcohol dehydrogenation. The Krische allylation, in contrast to other allylation techniques, does not require preexisting allyl metal reagents and allows for the direct conversion of primary alcohols into secondary homoallylic alcohols (precluding alcohol to aldehyde oxidation). For the manufacture of polyketide natural compounds, enantioselective carbonyl allylations are often used. Using a chiral allylmetal reagent, an allylborane produced from camphor, Hoffmann reported the first asymmetric carbonyl allylation in 1978.