No abstract

In this report, the synthesis and properties of an ester-functionalized macrocyclic sexifuran (C6FE) are presented.

Ac oncise route for construction of the ACDE ring skeleton in calyciphyllineA type alkaloids was developed using an intramolecular [5+ +2] cycloaddition reaction of an oxidopyrylium species bearing at etrasubstituted olefin. Key to the successo ft his reactionw as the combination of acid and base, which accelerated the construction of this skeleton containing as piro ring and vicinal quaternaryc arbon centers. The resultant tricyclicA DE ring compound was converted to an ACDE ring model through CÀHo xidation anda na za-Wittig reaction.

A concise synthesis of the ACDE tetracyclic ring system of calyciphylline A-type alkaloids was investigated. The intramolecular Diels–Alder reaction of a tetrasubstituted olefin with furan enabled the construction of the ACD ring system bearing two contiguous quaternary carbons in one step, and subsequent intramolecular [3+2] cycloaddition successfully gave the E ring.