Photochemical isomerisation of some diazo-compounds into diazirines

Abstract

SzcifimaryThe isomerisation of some diazo-acetamides into diazirinyl-aniides has been effected with visible light. DURING our investigations of the photochemistry of 01diazo-amides,l a study of the effect of wavelength revealed that irradiation of diazo-acetamides with visible light gave the isomeric diazirinyl-amides in about ZOO;, isolated yield.For example, N-diazoacetylpiperidine (1 ; R1 = C,H,,S, R2 = H), prepared from N-glycylpiperidine by treatment with nitrous acid, gave on irradiation with visible light for

Valence Isomerization between Diazo Compounds and Diazirines

“…It was thus postulated that α-keto-diazirines can be stabilized not only by conjugation [109] or by a neighboring amide moiety, [92,104] but also by some other still unknown factors. [88] Another stable spirodiazirine -compound 115 -was obtained from the diazocamphor 122 (Scheme 43).…”

“…98°C), each with only one substituent attached to a diazirine moiety. [104] Close analogues such as ethyl diazoacetate (160), diazoacetone (161), and diazoacetophenone (162) are also monosubstituted diazocarbonyls and might also have given monosubstituted diazirines, but did not. [92] In this they resemble the disubstituted diazoamides 153b, 158b, and 163 which gave no detectable diazirines upon irradiation.…”

“…Irradiation of the diazoamide 126e with visible light (Scheme 48) thus drove the reaction towards the diazirine 125e whereas use of UV light led to the formation of the cyclic lactams 165e and 166e. [104,111] Scheme 48. Photolysis of diazomonoamides.…”

“…[104] Irradiation of N-diazoacetylpiperidine (153a, Scheme 46) with visible light gave N-(diazirinylcarbonyl)piperidine (154a, IR: 1655 cm -1 ) in low yield. UV light caused nitrogen elimination and the formation of the azabicycle 155.…”

“…[104] The number of discovered isomerizations of diazo compounds remains rather limited to date. This might be due to a variety of difficulties.…”