Formation of pyrimidine-5-carboxaldehydes, 1-aminoethylene-2,2-dicarboxaldehyde and 2-amino-4-anilino-1,3,5-triazine from triformylmethane and amidines

Triformylmethane (1) reacted with benzamidine, guanidine and S-methyl- isothiourea to give the corresponding 2-substituted pyrimidines-5-car- boxaldehydes. However, reactions of (1) with acetamidine (or formami- dine) and phenylbiguanide gave the unexpected 1-aminoethylene-2,2-di- carboxaldehyde (5) and 2-amino-4-anilino-1,3,5-triazine (9), respecti- vely