Practical and Effficient Methods for Sulfonylation of Alcohols Using Ts(Ms)Cl/Et3N and Catalytic Me_3Ncentre dotHCl as Combined Base:Promising Alternative to Traditional Pyraditional Pyridine

摘要

Several alcohols were smooghly and practically tosylated by two methods A and B. Method A uses the TsCl/Et_3N(1.5-2.5 equiv)/cat. Me_3Ncenter dot HCl(0.1-1.0 equiv)reagent. Compared with the traditonal Py-solvent method,the method A has merits of its much higher reaction rate,operational simplicity, economy in the use of the amine, and circumvention of the undesirable side reaction from R-OTs to R-Cl. Method B uses TsCl/KOH [or Ca(OH)_2]/cat. Et_3N(0.1 equiv)/cat. Me_3Ncentre dot HCl(0.1 equiv)as the reagent, which will be suited for practical and large scale procuction for primary alcohols. On both methods A and B,a clear joint action of Et_3N and Me_3Ncentre dot HCl catalysts was observed. ~1H NMR measurements suport the proposed mechanism of the catalytic cycle. Related methanesulfonylation using Et_3N and cat. Me_3Ncentre dotHCl in toluene solvent also successfully proceeded, wherein the clear joint action was also observed.