Generation of Biradicals and Subsequent Formation of Quinolines and 5H-Benzo[b]carbazoles from N-[2-(1-Alkynyl)phenyl]ketenimines

Synthesis of aromatic heterocycles

“…124 The thermal ring closure of N-arylketenimines 82 to benzo-[b]carbazoles 83 is proposed to involve a diradical intermediate. 125, 126 Cyclisations of this type can also lead to the formation of quinolines, depending on the nature of the substituents (Section 14). Examples of the formation of carbazoles by oxidative cyclisation of diphenylamines 127 and from pentacarbonylchromium carbene complexes 128 have also been reported.…”

Tandem Synthesis of Benzo[b]carbazoles and Their Photoluminescent Properties

“…Exceptionally, Schmittel et al 8a. and Shi and Wang8b independently reported a strategy in which three of the four fused rings of benzo[ b ]carbazoles could be constructed in a single step through a biradical cyclization reaction of the isolated N ‐(2‐ a lkynylphenyl) ketenimines. Although this reaction offers high bond‐formation efficiency, the diversity of the products is much limited, owing to the instability of the ketenimines.…”

Synthesis of o-isotoluenes, o-quinodimethanes, and benzoenynyl carbodiimides and their cyclizations to polycyclic and heterocyclic compounds

“…Our group recently reported the use of iminophosphoranes 109, readily prepared from treatment of 2-(1-alkynyl)anilines 108 with dibromotriphenylphosphorane Ph 3 PBr 2, for the aza-Wittig reaction with diphenylketene to produce N- [2-(1-alkynyl)phenyl]ketenimines 110 (Scheme 23). 46 The ketenimines 110 then were converted to the quinolines 112 and/or the 5H-benzo [b]carbazoles 115 depending on the nature of the substituent at the acetylenic terminus under mild thermal conditions.…”

“…H NMR spectra of 6-butyl-5-dibutylmethylene-1,3-cyclohexadiene (34) C NMR spectra of 6-butyl-5-dibutylmethylene-1,3-cyclohexadiene 34H NMR spectra of 5-dibutylmethylene-6-pentyl-1,3-cyclohexadiene 35C NMR spectra of 5-dibutylmethylene-6-pentyl-1,3-cyclohexadiene 35H NMR spectra of 5-dibutylmethylene-6-isopropyl-1,3-cyclohexadiene (36) C NMR spectra of 5-dibutylmethylene-6-isopropyl-1,3-cyclohexadiene (36) H NMR spectra of 5-dibutylmethylene-6-phenyl-1,3-cyclohexadiene 37C NMR spectra of 5-dibutylmethylene-6-phenyl-1,3-cyclohexadiene 37H NMR spectra of 6-(1-cyclohexenyl)-5-dibutylmethylene-1,3-cyclohexadiene (38) C NMR spectra of 6-(1-cyclohexenyl)-5-dibutylmethylene-1,3-cyclohexadiene (38) H NMR spectra of 5-dibutylmethlene-6-(methoxymethyl)-1,3-cyclohexadiene 39C NMR spectra of 5-dibutylmethlene-6-(methoxymethyl)-1, 3-cyclohexadiene (39) H NMR spectra of 6-(cyclohexylmethyl)-5-dibutylmethylene-1,3-cyclohexadiene (40) C NMR spectra of 6-(cyclohexylmethyl)-5-dibutylmethylene-1,3-cyclohexadiene (40) H NMR spectra of 9-butyl-2,2-dimethyl-3,5,7,8-tridecatetraene (41a) C NMR spectra of 9-butyl-2,2-dimethyl-3,5,7,8-tridecatetraene (41a) H NMR spectra of 2-heptyn-1-ol 44C NMR spectra of 2-heptyn- 1-ol (44) H NMR spectra of 3-butyl-1,2-heptadiene (45) C NMR spectra of 3-butyl-1,2-heptadiene (45) H NMR spectra of 1-iodo-2-(trimethylsilyl)acetylene (46) viii C NMR spectra of 1-iodo-2-(trimethylsilyl)acetylene (46) H NMR spectra of 1-(trimethylsilyl)-5-butyl-3,4-nonadien-1-yne 47C NMR spectra of 1-(trimethylsilyl)-5-butyl-3,4-nonadien-1-yne 47H NMR spectra of 5-butyl-3,4-nonadien-1-yne 48C NMR spectra of 5-butyl-3,4-nonadien-1-yne 48H NMR spectra of allenyldicyclohexylborane (74) C NMR spectra of allenyldicyclohexylborane (74) H NMR spectra of 4-(1-cyclohexenyl)-3-methylphenol 80C NMR spectra of 4-(1-cyclohexenyl)-3-methylphenol 80H NMR spectra of 1-(1-cyclohexenyl)-5-iodo-2-methyl-4-(2-propenyl)benzene 81C NMR spectra of 1-(1-cyclohexenyl)-5-iodo-2-methyl-4-(2-propenyl)benzene…”

“…The iminophosphorane 205 was also allowed to react with the isocyanates 133, producing 209 as the major isomer and 212 as the minor isomer (Scheme 46). The results are summerized in Table 3.…”