Eb. Koroleva et al., PALLADIUM-CATALYZED STEREOCONTROLLED ENDO CYCLIZATION OF 3-HYDROXYPROPYL-1,3-CYCLOHEXADIENE LEADING TO VERSATILE FUSED TETRAHYDROPYRANS, Tetrahedron letters, 36(30), 1995, pp. 5397-5400
A palladium-catalyzed synthesis of stereodefined fused tetrahydropyran
s from 2-substituted 1,3-cyclohexadienes is presented. The reaction ta
kes place via an intramolecular 1,4-oxidation of the conjugated diene
via a (pi-allyl)palladium intermediate. The stereochemical outcome of
the reaction can be controlled to give either cis or trans 1,4-additio
n over the conjugated diene. The structure of the products was establi
shed by X-ray crystallography.