Synthesis and reactions of 2-bis(methylthio)methylene-1-methyl-3-oxoindole: A facile access to benzo- and heterocyclo-fused carbazoles and indoles

✍ Scribed by M.V.Basaveswara Rao; U.K Syam Kumar; H Ila; H Junjappa

• Publisher: Elsevier Science
• Year: 1999
• Tongue: French
• Weight: 845 KB
• Volume: 55
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(99)00655-9

✦ Synopsis

The synthesis and reactions of 2-bis(methylthio)methylene-l-methyl-3-oxoindole 5 as a novel 3-carbon 1,3-bielectrophilic component are described. Thus cycioaromatization of 5 with allyi, methallyl and crotyl Grignard reagents affords substituted carbazoles 12a-e in good yields. Cycloaromatization of 5 with various anions derived from aryl / heteroaryl acetonitriles and antipyrine gives novel benzoic]-( 16), naphtho[1,2-c]-(19), indoio[3,2-a]-(21), thieno[2,3-c]-(23), pyrroio[2,3c]-(25) and pyrazolo[4,3-b]-(29) carbazole ring systems in good yields. Similarly heterocycio[b]fused indoles like pyrido[3,4-b]-(36), pyrido[3,2-b]-(39) indoles and indolo[3,2-b]quinolizinium salt 42 were synthesized by cyclization of $ with lithioacetonitrile, lithioaminocrotonitrile, and 2-picolyl lithium respectively v/a our heteroaromatic annelation protocol.