Treatment of 4-chloro-2, 2-dimethylbutanal, prepared in high yield by means of a three-step procedure starting from ethyl isobutyrate, with successively sodium bisulphite, a primary amine and potassium cyanide in water afforded novel 1-alkyl-and 1-aryl-3, 3- dimethylpyrrolidin-2-carbonitriles in a convenient and environmentally benign way.