Aromatic derivatives of 2H-pyrimidino[5,6-b]-1,4-thiazine

5-R/sup 1/-3-(4-R-Phenyl)-2H-pyrimidino(5,6-b)-1,4-thiazines (R/sup 1/ = N(CH/sub 3/)/sub 2/) or OCH/sub 3/), which exist primarily in the 2H form, were synthesized by the reaction of omega-bromoacetophenones with 4-R/sup 1/-5-amino-6-thiopyrimidines. The electronic absorption spectra of ethanol solutions were recorded with a Specord UV-vis spectrophotometer. The electronic characteristics of the excited states of the Va molecule were calculated by the MO LCAO SCF CI method in the Pariser-Parr-Pople (PPP) variant with standard set of parameters; an estimate of the contribution of the fragments to the general molecular excitation was given for each electron transition with the use of quantitative locality criteria. The PMR spectra of solutions in CDCl/sub 3/ and (CD/sub 3/)/sub 2/SO were recorded.