Abstract
1. 2-Methyl-1, 4-naphthoquinone (K3) reacted with sulfhydryl compound to form a thioether linkage at 3-position of K3 with an absorption maximum at 420-430mμ. 2. For this reaction, molecular oxygen and alkaline metal ions such as Na+ and K+ were essential. One half mole of oxygen was consumed for the reaction of one mole of K3 with one mole of sulfhydryl compound. 3. The reaction product of K3 with cysteine was unstable and gradually turned to the insoluble amorphous polymer. By methylation of intermediate, it was identified to be methyl 5-methyl-6-methoxy-3H-naphtho [2, 1-b] [1, 4]-thiazine-2-carboxylate.
