Cyclopropyl azides azetines

Thermal ring expansion of cyclopropyl azides provides a general route (95 — 96) to alkyl- and aryl-azetines (79CB3914). 

In contrast, the photolysis of these azides at 350 nm leads only to the corresponding nitriles and olefins in yields of 90 l-(Alkylthio)cyclopropyl azides (164), readily accessible from the corresponding chlorides and bromides, are smoothly decomposed at ITC with nitrogen evolution. The main process is a ring enlargement to 2-(alkylthio)azetines (165), accompanied by cleavage to an alkyl thiocyanate and an alkene (equation 114). ... 

Cyclopropyl azides undergo thermal ring expansion to azetines in good yields, but photolysis leads only to cleavage into olefin, nitrogen, and a nitrile (Eq. 126).454 ... 

A number of 1-azetines have been obtained from thermolysis of cyclopropyl azides, nitriles and alkenes being side products. The cyclopropyl azides were obtained by transfer of a diazo-group from tosyl azide to cyclopropylamine anions or from carbene/carbenoid additions to vinyl azides. The azetine (1) was oxidized... 

Thermal or photochemical decomposition of cyclopropyl azides may give rise to 1-azetines and/or stereospecific fragmentation to olefin plus nitrile. In contrast to the photochemical reaction, substituents have a pronounced effect on the thermal reaction pathway. In general, substitution in the 2-position of the cyclopropyl azide... 

Azetines from cyclopropyl azides Regiospecific ring expansion... 

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