Chemoselective N-alkylation of 2-hydroxycarbazole as a model for the synthesis of N-substituted pyrrole derivatives containing acidic functions
1995; Elsevier BV; Volume: 51; Issue: 19 Linguagem: Inglês
10.1016/0040-4020(95)00232-w
ISSN1464-5416
AutoresDomenico Albanese, Dario Landini, Michele Penso, Giovanni Spanò, Artan Trebicka,
Tópico(s)Porphyrin and Phthalocyanine Chemistry
Resumo2-Hydroxycarbazole (1) was chemoselectively 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 (87–96%) 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.
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