title: Photoinduced cyclization of 3-acyl-2-halo-1-[(ω-phenylethynyl)alkyl]indoles to azaheterocyclo[1,2,3-lm]-fused benzo[c]carbazoles.
abstract: A one-pot synthesis of azaheterocyclo[1,2,3-lm]-fused benzo[c]carbazoles (2 and 3) has been developed by photocyclization of 3-acyl-2-halo-1-[(ω-phenylethynyl)alkyl] indoles (1) in good to excellent yields. All products are formed from 1 via two sequential photocyclization reactions. Two products, 9-chloro-7,8-dihydro-6H-benzo[c]pyrido[1,2,3-lm]carbazole (2a-h) and 7,8-dihydro-6H-benzo[c]pyrido[1,2,3-lm]carbazole (3a-h), are produced in the photocyclization of 2-halo-1-[(ω-phenylethynyl)alkyl]indole-3-carbaldehydes (1a-h). In contrast, only products 2a-h are produced in the photocyclization of 3-acetyl-2-chloro-1-[(ω-phenylethynyl)alkyl]indole-3-carbaldehydes (1o-t). The 9-H in 3a-h (n = 2) does originate from the formyl group in 1a-h via 1,5-hydrogen shift. The structures of three new products, 9-bromo-7,8-dihydro-6H-benzo[c]pyrido[1,2,3-lm]carbazole (2b), 9-chloro-10-methyl-7,8-dihydro-6H-benzo[c]pyrido[1,2,3-lm]carbazole (3h) and 12-chloro-7,8-dihydro-6H-benzo[c]pyrido[1,2,3-lm]carbazole (2w), have been corroborated by single-crystal X-ray structural analyses.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, People's Republic of China.
authors.forename: Shenci
authors.initials: S
authors.lastname: Lu
authors.forename: Ren
authors.initials: R
authors.lastname: Wang
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Zongjun
authors.initials: Z
authors.lastname: Shi
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Tu
mesh_terms: D001372:Aza Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D002227:Carbazoles / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D003500:Cyclization; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D007211:Indoles / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D055668:Photochemical Processes; D013237:Stereoisomerism
chemical_list: D001372:Aza Compounds; D002227:Carbazoles; D006571:Heterocyclic Compounds; D007211:Indoles