Competitive cyclisations of singlet and triplet nitrenes. Part 9. 2-(2-Nitrenophenyl)-benzothiazoles and -benzimidazoles

Abstract

M 5 4WT 2-(2-Nitrophenyl) benzothiazole, produced by deoxygenation of the corresponding nitro-compound or by thermolysis or photolysis of the related azide, gives indazolo [3,2-61 benzothiazole by attack on the benzothiazole nitrogen. Similar attack of the nitrene in 2-(2-nitrophenyl) benzimidazoles gives benzimidazoindazoles in good yield. However, with an appropriate l-substituent in the benzimidazole (e.g. M e or CHMe,) the nitrene in its triplet state (generated by acetophenone-sensitised photolysis or by thermDlysis of the azide bearing a 4-dimethylamino-group) preferentially attacks this substituent giving benzimidazoquinazolines.

Inter‐ and Intramolecular Photoinduced Electron Transfer of Flavin Derivatives with Extremely Small Reorganization Energies

“…The synthesis of DMA-Fl was carried out according to the literature. [47][48][49] The structure of DMA-Fl, which is optimized by DFT calculation with Gaussian 03 at B3LYP/6-31G(d) level (see Experimental Section), is shown in Supporting Information S13a. The dihedral angle made by aromatic ring planes was found to be approximately perpendicular (89.88).…”

The Conversion of 4-Anilinoquinazoline- and 3-Aryl-4-imino-3,4-dihydro-quinazoline-2-carbonitriles into Benzo[4,5]imidazo[1,2-c]quinazoline-6-carbonitriles via Oxidative and Nonoxidative C–N Couplings

“…4,5-Dichloro-1,2,3-dithiazolium chloride (11), 42 tetracyanoethene (TCNE), 43 21 4-(arylamino)quinazoline-2-carbonitriles 4a-c,e,f,i,j, 22b and 4-imino-3-phenyl-3,4-dihydroquinazoline-2-carbonitrile (5a) 22a were prepared according to literature procedures. (10) (14). (9), 309 (12), 307 (7).…”

“…These metal free conditions worked well for the parent, the 4-Me and the 4-MeO substituted analogues (Table 1, entries 1-3), however, the reactions with 4-anilinoquinazolines that hosted inductively electron withdrawing halogen substituents on the aniline moiety (Table 1, entries [6][7][8][9][10][11][12][13][14][15][16][17] required prolonged reaction times. As such, we re-optimized the reaction conditions Table 1.…”

“…Most syntheses of benzo­[4,5]­imidazo­[1,2- c ]­quinazolines focus on building the pyrimidine ring starting from 2-(2-aminophenyl)­benzimidazoles 2 ,,,, or via structurally related precursors, e.g., 2-(2-nitrophenyl)­benzimidazoles, N -[2-(benzimidazol-2-yl)­phenyl]­phosphanimines, 2-(2-azidophenyl)­benzimidazoles, N -[2-(benzimidazol-2-yl)­phenyl]­methanimines, ,, and 2-(2-halophenyl)­benzimidaz-oles . A second major synthetic route of benzo­[4,5]­imidazo­[1,2- c ]­quinazolines is via construction of the imidazole ring which has been limited to treatment of 4 H -benzo­[ d ]­[1,3]­oxazin-4-ones 3 with 1,2-benzenediamines either directly ,,,,, or via the isolable intermediate 3-(2-aminophenyl)-3 H -quinazolin-4-ones , or structurally related benzo­[1,3]­thiazin-4-ones …”

“…Benzo [4,5]imidazo [1,2-c]quinazolines also have hole transporting properties. 10 Most syntheses of benzo [4,5]imidazo [1,2-c]quinazolines focus on building the pyrimidine ring starting from 2-(2aminophenyl)benzimidazoles 2 1,3b,4b,6,11 or via structurally related precursors, e.g., 2-(2-nitrophenyl)benzimidazoles, 12 N- [2-(benzimidazol-2-yl)phenyl]phosphanimines, 13 2-(2-azidophenyl)benzimidazoles, 14 N- [2-(benzimidazol-2-yl)phenyl]methanimines, 5c,d,15 and 2-(2-halophenyl)benzimidazoles. 16 A second major synthetic route of benzo [4,5]imidazo- [1,2-c]quinazolines is via construction of the imidazole ring which has been limited to treatment of 4H-benzo [d] [1,3]oxazin-4-ones 3 with 1,2-benzenediamines either directly 5a,b,e,7b,11i,17 or via the isolable intermediate 3-(2-aminophenyl)-3H-quinazolin-4-ones 7b,18 or structurally related benzo [1,3]thiazin-4-ones.…”