Simple unsaturated nitriles [acrylonitrile, crotononitrile, and 2-cyanobutadiene (I)] were shown to undergo well-defined photochemical reactions. Mechanistic aspects of these reactions were studied with the aid of quantitative measurements. The isolation of 1- cyanobicyclobutane (111) as the major product from the photolysis of I suggests a diradical intermediate (IV).
![bicyclo[1.1.0]butane-1-carbonitrile结构式](https://image.chemsrc.com/caspic/446/16955-35-4.png)