DIHYDROPYRAN DERIVATIVES, PROCESSES FOR PREPARATION AND USE

摘要

The present invention relates to dihydropyran derivatives, processes for preparing, and processes of using the derivatives. The derivatives are prepared by condensation of lithium dienolate of prenal with an aldehyde or a ketone. The pyran derivative prepared from beta -ionylideneacetaldehyde when treated in the presence of a catalyst directly forms retinal.