Preparation and novel reduction reactions of vinamidinium salts

Substituted acetic acids and formamides react in the presence of phosphorus oxychloride to yield the vinamidinium hexafluorophosphate salts 5a-d, 6a-d , and 7 in moderate to good unoptimized recrystallized yields (40-67%) as e asily handled nonhygroscopic solids. The 1,3-differentially substituted vin amidinium salts 8 was prepared by amine exchange in 81% yield as are the cy clic diazapinium salts 9 and 10 in > 76% yield. The symmetrical 2-chlorovin amidinium 11 was prepared by displacement of 3 in 71% yield. The 2-chlorovi namidinium salts are cleanly reduced to the parent vinamidinium salts 12-16 using HI or PPh3/pTSA in up to 99% assay yield.