Diastereoselective Allylation and Crotylation Reactions of Aldehydes with Potassium Allyl- and Crotyltrifluoroborates under Lewis Acid Catalysis
作者:Robert A. Batey、Avinash N. Thadani、David V. Smil、Alan J. Lough
DOI:10.1055/s-2000-6303
日期:——
Potassium allyl- and crotyltrifluoroborates react with aldehydes in a process catalyzed by a variety of Lewis acids, to give the corresponding homoallylic alcohols. Of the Lewis acids examined, BF3 · OEt2, used either stoichiometrically or catalytically, was found to most efficiently catalyze this reaction. The air and moisture stable potassium organotrifluoroborate salts react with a variety of alkyl, α- or β-substituted alkyl, and aryl aldehydes, and lead to the adducts in high yield and with high diastereoselectivity.
Diastereoselective allylations and crotylations under phase-transfer conditions using trifluoroborate salts: an application to the total synthesis of (−)-tetrahydrolipstatin
作者:Avinash N Thadani、Robert A Batey
DOI:10.1016/j.tetlet.2003.09.053
日期:2003.10
A mild protocol for diastereoselective allylations and crotylations of α- and β-silyloxy substituted aldehydes utilizing potassium allyl/crotyltrifluoroborates is described. The reactions proceed to completion within 30 min at room temperature in biphasic or aqueousmedia in the presence of a phase transfer catalyst. The resulting homoallylic alcohols are obtained in high yields and moderate to excellent