DEAMINATION REACTIONS .54. DECOMPOSITION OF 1-CYANO-1-PROPANEDIAZONIUM IONS

The nitrous acid deamination of 2-aminobutanenitrile (9) was studied w ith regard to product distribution and stereochemistry. The formation of 2-(hydroxyimino)butanenitriles (21, 22; 8-28%) indicates the interv ention of 1-cyanopropyl radicals (24) that are captured by NO. The pol ar reactions lead mainly to elimination (10-13) and nucleophilic subst itution (14-16), rearrangement playing a minor role. (R)-9 was prepare d from (R)-2-aminobutanoic acid. The nitrous acid deamination of (R)-9 afforded the cyanohydrin 16 with 81% net inversion. Owing to destabil ization of the carbocation 26 by CN, the S(N)2 route of nucleophilic d isplacement is preferred over S(N)1. The influence of CN is shown to b e smaller than that of CF3.