Preparation and properties of some 1,2-dihydropyrimidinium salts

Abstract

Some 1,2-dihydropyrimidinium salts have been prepared and their spectra and chemical properties compared with those of 2,3-dihydro-1,4-diazepinium salts. They undergo deuteriation, halogenation, and possibly diazo-coupling, at the 5-position. The 5-bromo-derivatives are protodebrominated by thiourea but a 5-chloro-derivative was unaffected by this reagent. The 2,2-diethyl-4-methyldihydropyrimidinium salt reacted at the 6-position with piperidine to give a 1-amino-3-piperidinopropenylium salt and with ethylenediamine and its N-methyl- and NN′-dimethyl-derivatives to give dihydrodiazepinium salts.