Ammonium 1,1,3-tricyano-2-methylprop-2-enide 1a and sodium 2-amino-1,1,3-tr
icyanoprop-2-enide 1b are treated with H2S in absolute ethanol to afford 3,
4,6-trisubstituted pyridine-2(1H)-thione 3a,b; their structures are confirm
ed by reaction with phenacyl bromide to give 4a,b; also 3a,b reacts with DM
FDMA to give 6a,b, and on treatment of 6a with phenacyl bromide affords 8;
reaction of 4b with DMFDMA gave 9 while methylation of 3a,b by methyl iodid
e in ethanolic sodium hydroxide gives 10a,b.