SYNTHESES WITH PYRIDINIUM AND SULFONIUM SALTS OF ACYLATED BETA-ENAMINONITRILES

Pyridinium and sulfonium salts 2a-e which can be prepared from 3-amino -2-(alpha-haloacetyl)-crotonitriles and mino-2-(alpha-halo-acetyl)-3-p henyl-acrylonitriles react with malononitrile in the presence of a bas e to 3-amino-2-pyridinio-phenolates 3a,b and 3-amino-2-sulfonio-phenol ates 3c-e. In an analogous way, 3-amino-2-(diethyloxyphosphoryl)-pheno l 5a and 3-amino-2-(p-tolyl-sulfonyl)phenol 5b have been prepared. 2,3 -Diamino-phenoles 6a,b are formed from the pyridinium salts 3a,b. The behaviour of the pyridinium salts 2a,b towards heterocumulenes has bee n investigated. Cyanamide leads to the (2-amino-4-hydroxy-pyrid-3-yl)- pyridinium salt 8c. Phenylisothiocyanate gives the 3-pyridinio-2-thiox o-pyridin-4-olates 9a,b. Carbon disulfide gives rise to 3-pyridinio-2- thioxo-pyridin-4-olate 10 or 3-pyridinio-2-thioxo-thiopyran-4-olate 11 , depending on the substituent at the g-position. Phenylisocyanate rea cts to the pyrimidin-2,4-dione 12 with loss of N-methyl-pyridinium chl oride. S-methylation of 9a and cleavage of the pyridine moiety yields the 3-amino-2-methylthio-pyrid-4-one 14. The structures were investiga ted by H-1 and C-13 NMR spectroscopy.