Dihydrocytosine and related compounds

Abstract

In connection with a study of chemically induced mutations, a number of 5,6-dihydrocytosines have been synthesised by sodamide-catalysed ring-closure of the corresponding 2-cyanoethylurea and by amination of 4-thio-5,6-dihydrouracils. U.v. and i.r. spectra and pK_a values of dihydrocytosine and its 1-methyl, 1-cyclohexyl, 1,3-dimethyl, and 1,N(4)-trimethyl derivatives are recorded. 1-Alkyl dihydrocytosines and the parent compound exist in the amino-form (K_T 25) in water and predominantly in the imino-form in chloroform. The kinetics and mechanism of their rapid hydrolysis to dihydrouracils are discussed.