Stereochemistry of the formation of 4-alkoxyimino-5,6-dihydro-6-alkoxyaminopyrimidin-2(1H)-ones from cytosines and hydroxylamines

Abstract

High resolution ¹H and ¹⁹F n.m.r. data together with deuterium labelling studies are presented which reveal that the addition of hydroxylamines across the 5,6-double bond of cytosines is predominantly trans. The 4-alkoxyimino-5,6-dihydro-6-alkoxyaminopyrimidin-2(1H)-one products show syn/anti isomerism about the 4-alkoxyimino-group dependent on the substituent at N(3)(H or Me, respectively) and conformational changes throughout the molecules which are dependent on the substituents at N(1)(H or Me) and C(5)(H or F).