TRANSANNULAR DIELS-ALDER REACTIONS ON 14-MEMBERED MACROCYCLIC TRIENES.1. STEREOSELECTIVE SYNTHESES OF THE MACROCYCLIC TRIENES PRECURSORS

Transannular Diels-Alder reactions on 14-membered macrocycles containi ng properly located diene and methyl-substituted dienophile units lead to A.B.C.[6.6.6] tricycles related to steroids. To study the influenc e of the olefin and diene geometry on the stereochemical outcome of th e Diels-Alder reaction it was necessary to prepare macrocyclic trienes of well-defined stereochemistry. Eight different types of macrocyclic trienes might be obtained by the coupling of appropriate dienophiles arid dienes, namely, TTC, TTT, TCC, TCT, CTC, CTT, CCC, and CCT. In th is paper (first in a series of two), the synthesis of appropriately fu nctionalized dienophile and diene synthons, as well as their coupling reaction affording macrocyclic triene precursors, is described.