A FACILE GENERAL-SYNTHESIS OF 9-POSITION FUNCTIONALIZED HETERONIUMANTHRACENE SALTS

Heteroniumanthracenes react selectively as the cations (1a) or as the corresponding carbinol bases (9b,c) with benzotriazole to give the cor responding 9H-(benzotriazol-1-yl)heterocycles (10a-c). As novel hetero cyclic anion precursors, (10a-c) undergo smooth lithiations at the pos itions a to the benzotriazol-1-yl function, corresponding to the 9-pos ition of the heterocycles (1a) and (9b,c). Subsequent trapping of the benzotriazolyl stabilised carbanions (11a-c) with various long chain a lkyl halides forms intermediates of type (12b) which are converted by treatment with mineral acid, into the corresponding 9-functionalised h eteroniumanthracene salts (13-16) (or their free bases (17-19)) in goo d to excellent yields.