Organic Letters 2006-03-02

Synthesis of multi ring-fused 2-pyridones via an acyl-ketene imine cyclocondensation.

Nils Pemberton, Lotta Jakobsson, Fredrik Almqvist

Index: Org. Lett. 8(5) , 935-8, (2006)

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Abstract

Polycyclic ring-fused 2-pyridones (5a-e and 9a-e) have been prepared via a microwave-assisted acyl-ketene imine cyclocondensation. Starting from 3,4-dihydroisoquinolines (4a-b) or 3,4-dihydroharman (8), fused 2-pyridones could be prepared in a one-step procedure. By using either Meldrum's acid derivatives (1a-d) or 1,3-dioxine-4-ones (7a-b) as acyl-ketene sources, mono- or disubstitution of the fused 2-pyridone ring could be accomplished. As an application of the method, a formal synthesis of the indole alkaloid sempervilam was performed.