7-, 8-, 9-, and 10-Methylbenzo[a]fluorene. Preparation of o-iodotoluic acids via the thallium(III) bistrifluoroacetates

Abstract

Iodination of m- and p-toluic acid by successive reaction with thallium(III) trifluoroacetate and aqueous potassium iodide afforded 2-iodo-5-methyl- and 2-iodo-4-methyl-benzoic acid respectively; with o-toluic acid 5- and 6-iodo-2-methylbenzoic acids were obtained. Reaction of the three o-iodo-acids with lithium diphenylcuprate and lithium di-(2-naphthyl)cuprate gave the corresponding aryltoluic acids. The naphthyl acids were used in the synthesis of 8-, 9-, and 10-methylbenzo[a]fluorene; the 7-methyl isomer was prepared by a separate procedure.