Benzo 6 selenophene lithiation

The l-methylbenzo[A]thieno[2,3-/)]pyrrole (149) and benzo[6]selenolo[2,3-6]pyrrole (150) were prepared (83JHC49) and the influence of annelation and of the heteroatom upon the reactivity towards acetylation and lithiation was investigated <83JHC6l>. The sulfur and selenium analogues with [h,2-b (75)-(77) and [2,3-b (149) and (150) annelation were acetylated at C-2 and C-3. No reaction at all was observed with butyllithium except in the case of 1 -methylbenzo[6]selenolo[2,3-/ ]pyrrole (150), where the opening of the selenophene nucleus, after car-boxylation and the action of diazomethane, gave l-methyl-2-methoxycarbonyl-3-(2 -methyl-selenophenyl)pyrrole (151) and the positional isomer (152). 

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