Selective monosulfonylation of internal 1,2-diols catalyzed by di-n-butyltin oxide
摘要:
The reaction of internal 1,2-diols with catalytic n-Bu2SnO, p-TsCl (1.05 equiv.) and Et3N (1.1 equiv.) led to selective monotosylation. In the case of cyclic substrates, the cis-1,2-diol moiety appeared best suited for optimal results, supporting the intermediacy of a five-membered chelate. (C) 2000 Elsevier Science Ltd. All rights reserved.
Catalytic Regioselective Sulfonylation of α-Chelatable Alcohols: Scope and Mechanistic Insight
作者:Michael J. Martinelli、Rajappa Vaidyanathan、Joseph M. Pawlak、Naresh K. Nayyar、Ulhas P. Dhokte、Christopher W. Doecke、Lisa M. H. Zollars、Eric D. Moher、Vien Van Khau、Berta Košmrlj
DOI:10.1021/ja016031r
日期:2002.4.1
This paper describes a convenient protocol for the regioselective sulfonylation of alpha-chelatable alcohols. Typically, the reaction of alpha-heterosubstituted alcohols with 1 equiv of p-TsCl and 1 equiv of Et3N in the presence of 2 mol % of Bu2SnO leads to rapid, regioselective, and exclusive monotosylation. The pKa of the amine was correlated to the reaction rate. A plausible mechanism for this reaction has been proposed on the basis of Sn-119 NMR studies.