First stereospecific total synthesis of (-)-affinisine oxindole as well as facile entry into the C(7)-diastereomeric chitosenine stereochemistry

The first synthesis of (-)-affinisine oxindole was completed in an enantiospecific fashion from commercially available D-(+)-tryptophan in 10% overall yield. The asymmetric Pictet-Spengler reaction, diastereo-specific oxidative-rearrangement of a tetrahydro-beta-carboline, and stereospecific enolate-mediated palladium-catalyzed cross coupling process were key steps in the sequence. This represents the first example of a total synthesis via stereospecific entry into either the alstonisine related or epimeric chitosenine related oxindole stereochemistry depending on the presence or absence of an N-b-benzyl protecting group. (C) 2014 Elsevier Ltd. All rights reserved.