A study of several different reductions of α, β-unsaturated nitriles by NaBH4shows that these proceed by way of a 1:4 addition to form saturated nitriles. At long reaction times, hydrolysis products or those of substitution of the saturated nitrile are observed. The relative rates of reduction follow the order: 2-phenyl-2-butenenitrile1 > 2,3-diphenyl-2-propenenitrile2 > 3-phenyl-2-propenenitrile3 > 2-butenenitriIe4. [Journal translation]