Effect of Crown Ethers on the Regioselectivity of Allylation of Benzaldehyde with Allylic Barium Reagents

Article abstract of DOI:10.1055/s-1997-1530

An increase of α-regioselectivity was observed in the reaction of allylic barium reagents with aldehydes employing crown ether as an additive. For example, an α/γ regioselectivity was improved to 98/2 from 92/8, when an equimolar amount of 18-crown-6 was added to geranylbarium reagent in THF at -78°C prior to the reaction with benzaldehyde.