ANTI-HISTAMINICS OF THE FORMULA: ##SPC1## wherein R.sub.1 is alkyl, alkenyl or phenalkyl, R.sub.2 and R.sub.3 are hydrogen, alkyl or alkenyl, and R is an optional substituent, are prepared by reacting a 3,4-dihydro-1,3-dioxo-1H-pyrido [2,3-d][1,3]oxazine (a 3-azaisatoic anhydride) with a S-methyl-thiopseudourea.
公式为##
SPC1##其中R.sub.1为烷基,烯基或苯基甲基,R.sub.2和R.sub.3为氢,烷基或烯基,R为可选取代基团。通过将3,4-二氢-1,3-二氧杂-1H-
吡啶[2,3-d][1,3]噁嗪(3-氮杂异酸酐)与S-甲基
硫代伪
脲反应制备得到。