Synthesis of Helical Molecules Based on 5,6,6a,7,8,12b-Hexahydrobenzo[c]phenanthrene-5,8-dione

Abstract

Synthetic routes based on Newman's^1-7 synthesis of a number of polycyclic aromatic hydrocarbons were modified and developed to give a convenient preparation (Scheme 1) of 11 helical molecules formally based on hexalindione (1). In contrast to Newman's work determined the stereochemistry at C6a-C12b in (1a-k) and in some cases, were able to control it. We also investigated the competitive formation of six- and seven- membered rings in the reaction yielding the hexacyclic derivatives (1d, e). In addition, we report an unusual fragmentation (Scheme 2) leading to the unexpected by-product 4-methoxyacetophenone (16) in the synthesis of (1h).