Azetidines and Azetines

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 

Nitrogen analogues (5) of o-xylylenes are produced as transient intermediates in the flash pyrolysis of o-amino-benzyl alcohols (4). They do not undergo ring-closure to benzazetines but cyclize to acridines via dihydroacridines. Possibly the same type of imine methide is involved in the thermal and photochemical extrusion of sulphur dioxide from the cyclic sulphones (6), which in this case does give the benzazetine.  

Other papers of interest in connection with azetidines include further details of the photochemical formation of azetidine derivatives from 2-cyanopyrroline N-oxide, syntheses of 2- and 3-pyridylazetidines (as nicotine analogues), the photochemical addition of the isoxazoline (7) to benzene, furan, and thiophen, and several examples of [3 + 1] addition of isocyanides to azomethine ylides.  

2 Systems containing One Nitrogen Atom Azetidines and Azetines. - A new synthesis of azetidine, allowing its preparation on a large scale, has been described. The new method involves the addition of sodium azide to acrolein and reduction of the addition product to 

3-azidopropanol (I), whose reaction with triphenylphosphine, followed by distillation, gave azetidine in 30% yield. 

An improved preparation of 3,3-dimethylazetidine has also been reported, permitting the rate of formation of the enamine (2) to be studied.  

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Azetidines and Azetines.- Interesting studies of the interconversions of cyclic nitrones and azetidines have been made. The... 

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