A New Synthesis of 7-Ethyl-8-methyl-I,2-benzofluorene: Jacobs Hydrocarbon

A now synthesis of 7-ethyl-8-methyl-1,2-benzofluorene (Jacobs hydrocarbon) is described from 2,1- methoxycarbonylethyl.4,5-benzindan-1 -one (IV: R = Me), which has been prepared by two independent routes. The keto-ester (IV: R = Me) on the Stobbe condensation, followed by decarboxylation and esterification, affords the unsaturated di-ester (VIII). The saturated ester (IX: R= Me) or the corresponding acid on cyelisation provides a tetracyclie kotone (X), which on Grignard reaction, followed by dehydration and dehydrogena­tion, furnishes the desired hydrocarbon (I) in an excellent yield.