ChemInform Abstract: Unusual 1,2‐Migration in Organoaluminum Chemistry, Promoted by BF3·OEt2.

Abstract

184ChemInform Abstract Lithiation of dihydropyran (I) and subsequent treatment with trimethylaluminum (IV) generates the intermediate salt (V) which is coupled with cyclohexene oxide (VI) in the presence of boron trifluoride etherate, yielding the 3-cyclohexyl-2-methyltetrahydropyran (VII). The analogous reaction of (V) with benzaldehyde (VIII) gives the corresponding 2,3-disubstituted tetrahydropyran (X), whereas (III) and (VIII) produce the 2-hydroxybenzyldihydropyran (IX). The lithiated dihydrofuran (XI) reacts consecutively with the trialkylaluminum compounds (XII) and (VI) in the presence of boron trifluoride etherate to form the stereoisomeric 2-alkyl-3-cyclohexyltetrahydrofurans (XIII) and (XIV).