Studies on Pyrimidine Derivatives and Their Related Compounds. XCI. On the Oxidation Products of 2-Substituted-1, 4-thiazin-3-one Derivatives

Abstract

On treatment of 2-p-chlorophenylthiazinothiamine (Ib) with hydrogen peroxide, 2-hydroxy-2-p-chlorophenylthiazinothiamine (IIb) was obtained. Similar reaction products of phenyl-and methylthiazinothiamine (Ia and Ie) were reinvestigated and found to be IIb analogues (IIa and IIe, respectively). Reactions of IIa, IIb or IIe with acetic anhydride afforded the corresponding N-(2-methyl-4-aminopyrimidin-5-yl) methyl-N-(2-acetylthio-4-amino-1-methyl-1-butenyl) aryl (or methyl) oxalamide (IIIa, IIIb or IIIe, respectively). Treatment of 2-o-tolylthiazinothiamine (Ic) with hydrogen peroxide gave N-[1-(2-oxido-1, 2-oxathiolan-3-ylidene) ethyl]-N-[(2-methyl-4-aminopyrimidin-5-yl) methyl]-o-tolyloxalamide (VIIIc) as a major product and similar treatment of o-methoxyphenylthiazinothiamine (Id) with hydrogen peroxide gave 1-(2-methyl-4-aminopyrimidin-5-yl) methyl-2-methyl-3-(2-hydroxyethyl)-4-hydroxy-4-(2-methoxyphenyl)-⊿²-pyrrolin-5-one (XV). Oxidations of Ia, Ic and Id with m-chloroperbenzoic acid also gave VIIIc and the corresponding VIIIc analogues (VIIIa and VIIId, respectively). The mechanisms of these reactions are discussed as shown in Chart 2.