2-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.
CHEMOSELECTIVE N-ALKYLATION OF 2-HYDROXYCARBAZOLE AS A MODEL FOR THE SYNTHESIS OF N-SUBSTITUTED PYRROLE DERIVATIVES CONTAINING ACIDIC FUNCTIONS / D. ALBANESE, D. LANDINI, M. PENSO, G. SPANO, A. TREBICKA. - In: TETRAHEDRON. - ISSN 0040-4020. - 51:19(1995), pp. 5681-5688.
CHEMOSELECTIVE N-ALKYLATION OF 2-HYDROXYCARBAZOLE AS A MODEL FOR THE SYNTHESIS OF N-SUBSTITUTED PYRROLE DERIVATIVES CONTAINING ACIDIC FUNCTIONS
D. ALBANESEPrimo
;D. LANDINISecondo
;
1995
Abstract
2-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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