Novel sulfur containing 1 , 4-disubstituted-1 , 2 , 3-triazoles catalyzed by CuI in water

A new one-pot three component reaction of thiols, propargyl bromide and organic azide for the synthesis of novel sulfur containing 1,4-disubstituted-1,2,3-triazoles was demonstrated. The protocol is simple, mild and green. The reactions are performed under aerial condition and at room temperature using CuI as a cheap and available catalyst.


Results and discussion
Initially, we investigated the effect of solvent on the model reaction of thiophenol, propargyl bromide and benzyl azide using CuI and Et 3 N for 24 h in air and at ambient temperature (Table 1).As can be seen from Table 1, the best result was obtained when water was used as solvent.
Moreover, in comparison with Et 3 N and DIPEA, Et 3 N performed the reaction better.Our further attempts to improve the yield by increasing temperature or adding sodium dodecylsulfate (SDS) additive to the reaction mixture, proved to be unsuccessful.In addition, the As clear from Table 2, the reaction was performed smoothly with thiols bearing both electrondonating and electron-withdrawing groups (3b-d, 3j, Table 2).However, due to their hydrogen's lower acidity, aliphatic thiol gave weak result (Table 2, 3e) and even in the case of n-octanethiol, no product was isolated (Table 2, entry 11).It was also indicated that the presence of electronwithdrawing groups on the azides used, could decrease the yield (Table 2, 3f and 3g).Finally, steric effect was observed comparing the results obtained for 2-and 4-methyl thiophenol reactions (Table 2, entries 3 and 10).

Conclusion
In summary, we have demonstrated a new one-pot three component reaction of thiols, propargyl bromide and organic azides for the synthesis of novel sulfur containing-1,4disubstituted-1,2,3-triazoles.The protocol is simple, green and mild using a cheap and available CuI.Moreover, the reactions could be performed in air without further considerations.

Synthesis of organic azides
Azides were synthesized according to the procedure reported by Campbell-Verduyn et al. [31].
To a stirred solution of the corresponding benzyl bromide (1 eq.) in a 50 mL water/acetone mixture (1:4) was added NaN 3 (1.5 eq).The resulting suspension was stirred at room temperature for 24 h.Dichloromethane was added to the mixture and the organic layer was separated.The aqueous layer was extracted with 3 × 10 mL aliquots of dichloromethane and the combined organic layers were dried over MgSO 4 .Solvent was removed under reduced pressure, and the azide was sufficiently pure to use without further work up.
Gereral procedure for the synthesis of sulfur containing-