Chemoselective N-alkylation of 2-Hydroxycarbazole as a Model for the Synthesis of N-Substituted Pyrrole Derivatives Containing Acidic Functions

Article abstract of DOI:10.1016/0040-4020(95)00232-W

2-Hydroxycarbazole (1) was chemoselectivity N-alkylated with several alkyl halides 3 by generating the corresponding N,O-dianion using excess sodium hydride in a suitable solvent, under anhydrous conditions.The highest yields, (87-96percent) of 9-alkyl-2-hydroxycarbazoles 4 and the mildest reaction conditions were reached in THF containing DMF as an additive (2 mol equiv), but other solvents (DMSO, diglyme, DME) or solvent-additive systems (THF-diglyme, THF-DMSO, DME-DMF, diglyme-DMF) are effective.