REACTIONS OF NITROGEN CONTAINING AROMATIC ANIONS WITH CHLOROCARBENE

Article abstract of DOI:10.1016/S0040-4020(01)91924-6

It is shown that the 4-azapentalene anion (1) and the dipyrrolo<1,2c:2'1'e>imidazolyl anion (2) (Li salts) undergo eliminative ring fission upon reaction with chlorocarbene in tetrahydrofuran.Acetylenes (12 and 18) are the result.The reaction of 1 is accompanied by ring enlargement to indolizine (7).When the reaction of 1 with chlorocarbene is performed in diethylether, again 7 is produced, this time accompanied by a tetracyclic valence isomer, the pyrroloazabenzvalene (8).Mechanistic implications, based on the finding that the site of label incorporation in the enlarged products is solvent dependent, are discussed and compared with the corresponding reactions of carboaromatic anions.Use of intramolecular oxidative coupling for the synthesis of new pyrrolo annellated heterocyclic systems is made throughout this work.