Convenient synthesis of highly optically active 2,3,4,6-tetrasubstituted tetrahydropyrans via Prins cyclization reaction (PCR) of optically active homoallylic alcohols with aldehydes

Prins cyclization reaction (PCR) of optically active homoallylic alcohols, RaC*H(OH)CH2CHCHCH3 (1-substituted but-2-en-1-ol), with aldehydes (RbCHO) in the presence of an acid-catalyst (HX) affords (2-Rb,3-CH3,4-X,6-Ra)-tetrasubstituted tetrahydropyrans highly stereoselectively in good yields.

Graphical Abstract