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Synthesis, Stability, and Photoreactivity of Diazirinyl‐Substituted N‐ Heterocycles Based on Indole, Benzimidazole, and Imidazole
Author(s) -
Raimer Björn,
Wartmann Thomas,
Jones Peter G.,
Lindel Thomas
Publication year - 2014
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201402354
Subject(s) - chemistry , carbene , trifluoromethyl , benzimidazole , imidazole , thermal decomposition , singlet state , photochemistry , medicinal chemistry , diazirine , indole test , decomposition , silsesquioxane , thermal stability , organic chemistry , catalysis , polymer , alkyl , physics , nuclear physics , excited state
The synthesis, thermal stability, and photoreactivity of trifluoromethyl diazirines installed at the heterocyclic section of N ‐methylindole, N ‐methylbenzimidazole, and at N ‐methylimidazole were investigated. N ‐Tosyl‐3‐diazirinylindole and N ‐methyl‐2‐diazirinylbenzimidazole proved to be thermally stable, whereas the corresponding 2‐diazirinylindole was not. The least stable was 2‐diazirinylimidazole, which underwent rapid decomposition. Quenching with ethanol indicated that the corresponding carbene was formed. Decomposition is rationalized by exothermic coarctate ring‐opening of the carbene. Quantum mechanical calculations [B3LYP/6‐311G(2d,2p)] predict singlet ground states of all carbenes. Accordingly, Friedel–Crafts alkylation products were formed on irradiation (350 nm, Rayonet) of the N ‐methylbenzimidazole‐based diazirine in the presence of phenol.