“…Where both of these methods involved specialized equipment (microwave oven, ultrasonic processor) and high temperature, we have previously reported simple, room temperature synthesis of various 2,3-diaryl-2,3-dihydro-4H-1,3-thiazin-4-ones [5,[12][13][14], including a few 2-aryl-3-phenyl-2,3-dihydro-4H-pyrido[3,2-e][1,3]thiazin-4-ones [4,5,15], using amide coupling agent 2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphorinane-2,4,6-trioxide (T3P). T3P has several advantages over other amide-forming reagents, including that the reagent is safe, the by-products are water soluble and easily removed, and in combination with pyridine epimerization at the carbon alpha to the carboxylic acid is minimized [16].…”