Stereoelectronic factors in bridgehead C-H bond insertion: studies toward the total synthesis of maoecrystal V

摘要

A strategy for the total synthesis of maoecrystal V is presented. The key interior vicinal quaternary carbon centers will be formed via sequential bridgehead C-H bond insertion and enolate functionalization. Studies herein validate the C-H bond insertion as feasible in model studies, though there are significant effects on the selectivity for the bridgehead position from neighboring groups. Both inductive electron withdrawing elements and sterics play a role in deactivating that position, with the former having a greater effect. Forming the second quaternary carbon is possible via enolate acylation and alkylation. Lastly, an approach to synthesize the cyclohexenone ring of maoecrystal V is described. (C) 2016 Elsevier Ltd. All rights reserved.