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  • Synthesis of carbazoles by intramolecular arylation of diarylamide anions.

Synthesis of carbazoles by intramolecular arylation of diarylamide anions.

The Journal of organic chemistry (2009-05-23)
María E Budén, Victoria A Vaillard, Sandra E Martin, Roberto A Rossi
ABSTRACT

The synthesis of a series of substituted 9H-carbazoles by the photostimulated S(RN)1 substitution reaction with diarylamines as starting substrate was performed. The diarylamines were obtained by two approaches, the Pd-catalyzed reactions (Buchwald-Hartwig) or Cu-catalyzed reactions of 2-haloanilines with aryl halides, or 2-bromoiodobenzene with anilines, with moderate to very good isolated yields (45-89%). Through an intramolecular C-C bond formation of diarylamines by the S(RN)1 mechanism, carbazoles were achieved. These reactions proceeded synthetically in very good to excellent yields (81-99%) in liquid ammonia and DMSO. The reaction of N-(2-bromophenyl)-2-phenylbenzenamine gave 1-phenyl-9H-carbazole (38%) and the isomer 9H-tribenz[b,d,f]azepine (58%). By using this methodology, 9H-carbazoles, substituted 9H-carbazoles, benzocarbazoles, and even 3,3'-bi(9H-carbazole) were obtained by a double S(RN)1 reaction with benzidine.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
2-Bromoiodobenzene, 99%
Sigma-Aldrich
Benzidine, ≥98.0% (N)
Sigma-Aldrich
Benzidine dihydrochloride, ≥99% (titration)
Supelco
Benzidine, analytical standard