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Photoinduced electron transfer , nitrile ylide

The ring opening of azirines under conditions of photoinduced electron transfer (PET) gives, not a nitrile ylide, but the short-lived 2-azaallenyl radical cation 108... [Pg.489]

The formation of the [3 + 2] cycloadduct 89 can be explained by two different reaction pathways (Scheme 36). Irradiation at 300 nm leads to ring opening of the azirine 88 to the nitrile ylide as an intermediate which adds to C6o yielding the observed product 89. No product formation is observed at wavelengths > 400 nm. Instead, under photoinduced electron transfer conditions in the presence of... [Pg.706]

Various other [3 + 2] cycloadditions, affording chiral, anellated C6o derivatives with stereogenic centers in the addends are reported in literature. The products were generally obtained as racemates and resulted from reaction of buckminsterfullerene with species like 2,3-disubstituted 2//-azirincs (via nitrile ylides [under direct irradiation] or via 2-azaallenyl radical cations [sensitization by photoinduced electron transfer]),365 1-substituted 5-diazopentane-1,4-diones (via cyclic carbonyl ylides),366 7-alkylidene-2,3-diazabicyclo[2.2.1] hept-2-ene (via a diradicaloid trimethylenemethane derivative),367 1-benzylpy-razolidine-3-ones in the presence of aldehydes (via pyrazolidinium ylides),368 2-trifluoromethyl-2,5-dihydro-l,3-oxazol-5-ones (via nitrile ylides),369 nitro-alkanes in the presence of triethylamine and trimethylsilyl chloride (via N-silyloxynitrones),370 or dv-HOCH2 CH=C H C H 2 OCO 2 H( in the presence of... [Pg.88]


See other pages where Photoinduced electron transfer , nitrile ylide is mentioned: [Pg.7]    [Pg.18]   


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