Long chain phenols. Part 15. Synthesis of 6-n-alkylsalicylic acids (and isomeric acids) from fluoroanisoles with alkyl-lithium

Abstract

Various n-alkyl-lithiums have been prepared in ether. They react with both 2- and 3-fluoroanisoles to give, after carbonation, mainly 6-alkyl-2-methoxybenzoic acids. 4-Fluoroanisole gives 2-alkyl-4-methoxybenzoic acids. These reactions probably involve methoxybenzynes and the factors affecting orientation of addition of LiR to these are discussed. Interaction of alkyl-lithium addition products, from 2- and 3-fluoroanisole, with water gave the 3-alkylanisole and, in the case of 4-fluoroanisole, this was accompanied by a small proportion of the 4-alkylanisole. Demethylation of the 6-alkyl-2-methoxybenzoic acids provided syntheses of several naturally occurring anacardic acids.