Bromonium-Initiated Epoxide-Opening Cascades : total Synthesis of ent-Dioxepandehydrothyrsiferol and Synthetic Studies toward (+)-Scholarisine A

Abstract

CHAPTER I. Bromonium-Initiated Epoxide-Opening Cascades: Total Synthesis of ent-Dioxepandehydrothyrsiferol Our foray into the total synthesis of ent-dioxepandehydrothyrsiferol has led to the discovery and development of the bromonium-initiated epoxide-opening cascade. This transformation constructs the signature trans-anti-trans tricyclic portion of the natural product containing the bromo-oxepane in a single step. Further explorations into this cascade also revealed feasibility of incorporation of exogenous trapping nucleophiles into the reaction. [chemical formulae] CHAPTER 11. Synthetic Studies toward (+)-Scholarisine A. A concise and scalable route toward the monoterpene indole alkaloid (+)- scholarisine A has been developed. Synthetic highlights of the route include: 1) cisselective Diels-Alder cycloaddition reaction to construct strained 5,6-fused hydrindanones, 2) a novel indole formation via an in-situ aza-Wittig reaction, and 3) a selective enolization and hydrolysis sequence of a diketone substrate to provide rapid access to a key tetracyclic intermediate. Studies to access the natural product via latestage intramolecular indole alkylations are presented. [chemical formulae]