Regioselective Addition of 5-Amino-l,2,4-Triazoles and Its Analogues with Arylsulfonyl Isocyanates

5-Amino-3-benzyl (aryl)thio-1,2,4-triazoles and its analogues (pyrazole) 1 are important intermediates for the syntheses of a lot of biological active compounds^1,2]. In our previous paper^3], we reported the regioselective addition of 1 with aryl isocyanates and the experimental results showed that the orientation of the addition of 5-amino-3-benzyl (aryl)thio-1,2,4-triazoles and its analogues with the aryl isocyanates can be directed by controlling the reaction temperature.The 1-position adduct 2 was obtained regiospecifically below 120℃, whereas the 5-position adduct 3 was obtained selectively when the reaction temperature was raised to 170℃ (Scheme 1).