Practical and efficient methods for sulfonylation of alcohols using Ts(Ms)Cl/Et3N and catalytic Me3H·HCl as combined base: Promising alternative to traditional pyridine
1999; Elsevier BV; Volume: 55; Issue: 8 Linguagem: Inglês
10.1016/s0040-4020(99)00002-2
ISSN1464-5416
AutoresYoshihiro Yoshida, Yoshiko Sakakura, Naoya Aso, Shin Okada, Yoo Tanabe,
Tópico(s)Asymmetric Synthesis and Catalysis
ResumoSeveral alcohols were smoothly and practically tosylated by two methods A and B. Method A uses the TsCl / Et3N (1.5–2.5 equiv) / cat. Me3N·HCl (0.1–1.0 equiv) reagent. Compared with the traditional 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. Et3N (0.1 equiv) / cat. Me3N·HCl (0.1 equiv) as the reagent, which will be suited for practical and large scale production for primary alcohols. On both methods A and B, a clear joint action of Et3N and Me3N·HCl catalysts was observed. 1H NMR measurements support the proposed mechanism of the catalytic cycle. Related methanesulfonylation using Et3N and cat. Me3N·HCl in toluene solvent also successfully proceeded, wherein the clear joint action was also observed.
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