[1,4]-SIGMATROPIC AND [2,3]-SIGMATROPIC REARRANGEMENTS OF YLIDES GENERATED FROM PHA-CYANO)ALLYL-N-CYANOMETHYL-N,N-DIMETHYLAMMONIUM PERCHLORATES

pha-Cyano)allyl-N-cyanomethyl-N,N-dimethylammonium perchlorates 3a-c w hen treated with solid K2CO3-DMSO (system A) afforded the alpha-cyano enamines 6a-c by a [1,4] shift of the alpha-cyano allylides 4a-c(+-); when treated with solid NaHCO3-DMF (system C), however, these gave a-a mino nitriles 8a-c, by a [2,3] shift of the cyano methylides 5a-c(+-). Reaction of the salts 3a,b with aq. NH3-CH2Cl2 (system B) led to the formation of 8a,b, while the salt 3c, under the same conditions, yield ed a mixture of 6c and 7c. It is postulated that the high tendency of 3a-c to undergo a [1,4] shift via the respective ylides, in contrast t o the corresponding benzylammonium salts, is due to a different charge distribution in the anionic parts of the allylides and benzylides.