The Metal-Ammonia Reduction of 1-Naphthoic Acid

Abstract

The reduction of aromatic compounds with alkali metals in liquid anhydrous ammonia (Birch Reduction and its modifications) has developed as an effective method for the synthesis of 1,4-cyclohexadiene derivatives, and has been the subject of several reviews.^1,2 In many cases, particularly with polynuclear compounds,² the reaction is complicated by subsequent isomerizations, and/or the reduction of initial products which are often themselves subject to reduction under the reaction conditions. Recently, we have shown that inverse quenching techniques can provide a substantial improvement in this reduction reaction by minimizing the effect of excess metal during the quenching process.³ Application of these methods to 1-naphthoic acid 1 have not only provided an excellent synthesis of 1,4-dihydro-1-naphthoic acid, but we believe will furnish a much improved general technique f o r the reduction of polynuclear aromatic carboxylic acids.