Reactions of allyl alcohols of the pinane series and of their epoxides in the presence of montmorillonite clay

The reactivity of allyl alcohols of the pinane series and of their epoxides in the presence of montmorillonite clay in intra- and intermolecular reactions was studied. Mutual transformations of (+)-trans-pino-carveol ((+)-2) and (-)-myrtenol ((-)-3a) were major reactions of these compounds on askanite-bentonite clay (Schemes 1 and 2). However, the two reactions gave different isomerization products, indicating that the reactivity of the starting alcohol (+)-2 or (-)-3a was different from that of the same compound (+)-2 or (-)-3 formed in the course of the reactions. (-)-cis- and (+)-trans-Verbenol ((-)-16 and (+)-12, resp.), as well as (-)-cis-verbenol epoxide ((-)-20) reacted with both aliphatic and aromatic aldehydes on askanite-bentonite clay giving various heterocyclic compounds (Schemes 4, 5 and 7); the reaction path depended on the structure of both the terpenoid and the aldehyde.