Prof. Manas Chakrabarty http://192.168.1.40:8080/xmlui/handle/123456789/1105 2026-05-31T12:08:43Z An expedient, regioselective synthesis of 2-alkylamino- and 2-alkylthiothiazolo[5,4-e]indoles http://192.168.1.40:8080/xmlui/handle/123456789/2423 An expedient, regioselective synthesis of 2-alkylamino- and 2-alkylthiothiazolo[5,4-e]indoles Chakrabarty, Manas; Kundu, Taraknath; Arima, S.; Harigaya, Y. 1-Benzenesulfonyl-5-aminoindole 5, prepared from 5-nitroindole 3, was condensed with alkyl isothiocyanates and separately with carbon disulfide and alkyl bromides/iodides to furnish efficiently the corresponding N-alkyl-thioureidoindoles 6a-c and the alkyl N'-(indol-5'-yl)dithiocarbamates 9a-e, respectively. Their cyclisation using N-bromosuccinimide (NBS) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), in the cold, followed by indolic N-deprotection, furnished regioselectively the 2-alkylamino- and the 2-alkylthiothiazolo[5,4-e]indoles 8a-c and 11a-e, respectively, in good overall yields. DOI: 10.1016/j.tetlet.2005.02.125 2005-04-18T00:00:00Z A new catalytic application of a keggin acid in the synthesis of symmetrical bis(indolyl)alkanes http://192.168.1.40:8080/xmlui/handle/123456789/2421 A new catalytic application of a keggin acid in the synthesis of symmetrical bis(indolyl)alkanes Chakrabarty, Manas; Mukherji, Ajanta; Karmakar, Sulakshana; Arima, S.; Harigaya, Y. Silicotungstic acid, H4SiW12O40, an important Keggin heteropoly acid, efficiently catalysed the reaction of indoles with aryl aldehydes in ethyl acetate solution at room temperature to furnish symmetrical bis(indolyl)alkanes expeditiously. DOI: 10.3987/COM-05-10587 2006-02-01T00:00:00Z A facile clay-mediated synthesis of 3,3-diindolyl-2-indolinones from isatins http://192.168.1.40:8080/xmlui/handle/123456789/2419 A facile clay-mediated synthesis of 3,3-diindolyl-2-indolinones from isatins Chakrabarty, Manas; Sarkar, Sandipan; Harigaya, Y. Dry reaction of isatins (3a, 3b) with indoles (4a-e) on montmorillonite K10 clay at room temperature furnished within minutes 3,3-bis(3'-indolyl)-2-indolinones (1a-f) in high yields. 5-Nitroisatin (3c) furnished, in addition to the expected indolinone 1h, 3-hydroxy-3-(3'-indolyl)-5-nitro-2-indolinone (6), a likely intermediate to 1h. 2005-08-01T00:00:00Z A novel, expedient synthesis of thiazolo[4,5-c]- and -[5,4-b]carbazoles http://192.168.1.40:8080/xmlui/handle/123456789/2417 A novel, expedient synthesis of thiazolo[4,5-c]- and -[5,4-b]carbazoles Chakrabarty, Manas; Ghosh, Nandita; Harigaya, Y. A new synthesis of thiazolo[4,5-c]- and -[5,4-b]carbazoles (6a-e, 7a, 8b-e) was accomplished from 3-aminocarbazoles (3a-e) by separate condensations with methyl and phenyl isothiocyanates, followed by oxidative cyclization of the resulting thioureidocarbazoles (4a-e, 5a). 2004-01-01T00:00:00Z