Unified enantioselective total syntheses of (?)-scholarisine G, (+)-melodinine E, (?)-leuconoxine and (?)-mersicarpine?

Chemical Communications Pub Date: 2019-02-26 DOI: 10.1039/C8CC09949A

Abstract

A unified strategy enabled the enantioselective syntheses of (?)-scholarisine G, (+)-melodinine E, (?)-leuconoxine and (?)-mersicarpine from a common 2-alkylated indole intermediate bearing an all-carbon quaternary stereogenic center. The Smith-modified Madelung indole synthesis was used to couple simple o-toluidine with chiral lactone (+)-8, incorporating the key elements for further cyclizations. Lactone (+)-8 was prepared via a palladium-catalyzed intermolecular asymmetric allylic alkylation. The unified and protecting-group-free reaction sequences allowed the synthesis of these alkaloids in a maximum of 10 steps and with high efficiency.

Graphical abstract: Unified enantioselective total syntheses of (?)-scholarisine G, (+)-melodinine E, (?)-leuconoxine and (?)-mersicarpine
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