Isomerization valence, diazoalkanes

Valence isomerization of diazoalkanes into diazirines and vice versa is possible by photolysis, although it is always accompanied by dediazoniation. The photolysis of diazirines was investigated intensively in recent years (e.g., by O Gara and Dailey, 1992, and by Modarelli and Platz, 1993 see also the book of Michl and Bonacic-Koutecky, 1990). An electronically excited state is obtained that can, in principle, decay by at least four competitive pathways (Scheme 5-16) a) fluorescence, b) intersystem crossing with the production of triplet carbene, c) formation of an excited diradical followed by internal conversion and production of singlet carbene, and d)... 

Cycloaddition of diazoalkanes to diazabicyclo[2.2.0]hexanes (134) and subsequent extrusion of nitrogen affords diazatricyclo[3.2.0.02,4]heptanes (135) that are easily valence-isomerized to novel dihydrodiazepines (136) (84TL297). 

Diazoalkanes (305) can undergo valence isomerization to diazirines (306) upon photolysis, but reversal to the diazoalkane occurs both photochemically and thermally. 46,236cd Diazirines can be photolyzed back to the diazoalkane or directly to the carbene.247... 

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See also in sourсe #XX -- [ ]

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