Developing new procedures for the synthesis of tetrahydropyrans
in a very stereoselective manner is of great importance for the synthesis
of THP-containing natural products. Here, we report an interesting
protocol for the synthesis of polysubstituted halogenated tetrahydropyrans
by silyl-Prins cyclization of vinylsilyl alcohols, in which the nature
of the Lewis acid determines the outcome of the process. The methodology
has been applied to the synthesis of a known antinociceptive.