Transannular Diels–Alder cyclization of substituted 13-membered trienes. An approach to the B.C.D.[6.6.5] rings of the 14β-hydroxysteroids

The transannular Diels-Alder strategy has been applied to three 13-membered macrocyclic trienes whose characteristics are: a cis-trans diene and a cis methoxymethyl enol ether as the dienophile. The successful trials led to three 6.6.5 tricyles having a trans-syn-cis geometry exactly as in the B.C.D. rings of the 14 beta-hydroxysteroids.