Alternatives to N,N‐Diethyl‐2,4‐dimethoxybenzamide as a Precursor for the Synthesis of 6,8‐Dimethoxy‐3‐methyl‐3,4‐dihydro‐1H‐isochromen‐1‐one

Abstract

Although the amide group of N,N‐diethyl‐2,4‐dimethoxybenzamide facilitates directed ortho‐metallation and subsequent allylation of the aromatic ring, it is not readily hydrolyzed prior to conversion into the title isochromenone. This article describes the use of 1‐(2‐allyl‐4,5‐dimethoxybenzoyl)‐4‐methylpiperazine and N,N‐diethyl‐2‐(2‐hydroxypropyl)‐4,6‐dimethoxybenzamide as alternative substrates for conversion into 6,8‐dimethoxy‐3‐methyl‐3,4‐dihydro‐1H‐isochromen‐1‐one.

Keywords:

• 3,4‐dihydro‐1H‐isochromen‐1‐one
• directed ortho metallation
• N,N‐diethyl arylamide

Acknowledgments

This material is based upon work supported by the National Research Foundation under grant number 2053652. Support from the University of the Witwatersrand (University Research Council) is also gratefully acknowledged. W. A. L. V. O thanks African Explosives and Chemical Industries (AECI) (Modderfontein, South Africa) for a postgraduate fellowship.