Nitrenes and carbenes

Irradiation of l-(2-azidophenyl)-3,5-dimethylpyrazole affords the corresponding nitrene which cyclizes into the corresponding pyrazolo[l,2-u] benzotriazole 91JA6928 (compare with 84CHEC-I(5)167 formulae (341) and (342)). 

7 Reactions with Radicals and Electron-deficient Species Reactions at Surfaces 3.3.1.7.1 Carbenes and nitrenes 

The reaction of pyrrole with dichlorocarbene, generated from chloroform and strong base, gives a bicyclic intermediate which can be transformed to either 3-chloropyridine (155) or pyrrole-2-carbaldehyde (156). Indole gives a mixture of 3-chloroquinoline (157) and indole-3-carbaldehyde (158). The optimum conditions involve phase transfer (76S249, 76S798). Benzofuran reacts with dichlorocarbene in hexane solution to give the benzopyran (159), whereas benzothiophene fails to react. 

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Carbocations, Carbanions, Free Radicals, Carbenes, and Nitrenes... 

CARBOCATIONS, CARBANIONS, FREE RADICALS, CARBENES, AND NITRENES... 

Time-resolved spectroscopic techniques are important and effective tools for mechanistic photochemical studies. The most widely used of these tools, time-resolved UV-VIS absorption spectroscopy, has been applied to a variety of problems since its introduction by Norrish and Porter almost 60 years ago. Although a great deal of information about the reactivity of organic photochemical intermediates (e.g., excited states, radicals, carbenes, and nitrenes) in solution at ambient temperatures has been amassed with this technique, only limited structural information can be extracted from... 

Reactions of 1,3,4-oxadiazoles at the ring atoms with radicals, carbenes, and nitrenes or with other electron-deficient species are rather uncommon. CHEC(1984) and CHEC-II(1996) have reported very few examples of such reactions concerning oxadiazolinones and oxadiazolinethiones. This situation has not changed. 

Synthetic Reactions via C-H Bond Activation Carbene and Nitrene C-H Insertion... 

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