LiBF<sub>4</sub>: A MILD AND EFFICIENT CATALYST FOR THE TETRAHYDROPYRANYLATION OF ALCOHOLS AND THEIR DETETRAHYDROPYRANYLATION
作者:F. Kazemi、A. R. Kiasat、S. Ebrahimi
DOI:10.1081/scc-120003397
日期:2002.1
ABSTRACT Catalytic amount of lithium tetrafluoroborate in dry acetonitrile catalyzes an efficienttetrahydropyranylation of different types of alcohols to afford the corresponding tetrahydropyranyl ethers in high yields. Deprotection of tetrahydropyranyl ethers can also be achieved efficiently in the presence of lithium tetrafluoroborate in methanol. The chemoselectivity was observed in the protection
trifluoromethanesulfonate, [V IV (TPP)(OTf) 2 ], in the tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) is reported. This new electron-deficient V(IV) compound was used as a highlyefficient catalyst for pyranylation of primary (aliphatic and benzylic), sterically-hindered secondary and tertiary alcohols with DHP. Tetrahydropyranylation of phenols with DHP was also performed to afford