Stereoselective synthesis of functionalised carbocyclic amides: construction of the syn-(4aS,10bS)-phenanthridone skeleton.

Sajjad Ahmad, Michael D Swift, Louis J Farrugia, Hans Martin Senn, Andrew Sutherland

Index: Org. Biomol. Chem. 10(19) , 3937-45, (2012)

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Abstract

A new synthetic approach has been developed for the preparation of 7-deoxypancratistatin analogues bearing a syn-(4aS,10bS)-phenanthridone ring junction. A one-pot tandem process involving a substrate-directed Overman rearrangement and ring closing metathesis reaction was developed for the stereoselective synthesis of a carbocyclic allylic trichloroacetamide. Conversion to a 6-bromopiperonyl amide, followed by a Heck reaction generated a homoallylic alcohol and completed the syn-(4aS,10bS)-phenanthridone carbon skeleton. Stereoselective epoxidation and dihydroxylation of the syn-(4aS,10bS)-phenanthridone framework was then investigated leading to the preparation of new analogues of 7-deoxypancratistatin.