An ebselen like catalyst with enhanced GPx activity via a selenol intermediate

The reaction of KSeO^tBu with 2-iodo-arylbenzamides gave benzamide ring-substituted, quinine-derived isoselenazolones 1b–1d. The reaction of PhSH with ortho-methyl-substituted isoselenazolone 1b gave selenol 3b, which is oxidized by H₂O₂ to regenerate 1b. Isoselenazolone 1b shows a high rate (0.33 × 10³ μM min⁻¹) of oxidation of PhSH with H₂O₂, which is ∼10³-fold more active than ebselen (1a) and ≥30-fold more active than the other isoselenazolones of this study. Compound 1b shows less inhibition of the growth of yeast cells than 1a.