15051-88-4Relevant articles and documents
Regioselective, borinic acid-catalyzed monoacylation, sulfonylation and alkylation of diols and carbohydrates: Expansion of substrate scope and mechanistic studies
Lee, Doris,Williamson, Caitlin L.,Chan, Lina,Taylor, Mark S.
supporting information; experimental part, p. 8260 - 8267 (2012/07/14)
Synthetic and mechanistic aspects of the diarylborinic acid-catalyzed regioselective monofunctionalization of 1,2- and 1,3-diols are presented. Diarylborinic acid catalysis is shown to be an efficient and general method for monotosylation of pyranoside derivatives bearing three secondary hydroxyl groups (7 examples, 88% average yield). In addition, the scope of the selective acylation, sulfonylation, and alkylation is extended to 1,2- and 1,3-diols not derived from carbohydrates (28 examples); the efficiency, generality, and operational simplicity of this method are competitive with those of state-of-the-art protocols including the broadly applied organotin-catalyzed or -mediated reactions. Mechanistic details of the organoboron-catalyzed processes are explored using competition experiments, kinetics, and catalyst structure-activity relationships. These experiments are consistent with a mechanism in which a tetracoordinate borinate complex reacts with the electrophilic species in the turnover-limiting step of the catalytic cycle.
Catalytic regioselective sulfonylation of α-chelatable alcohols: Scope and mechanistic insight
Martinelli, Michael J.,Vaidyanathan, Rajappa,Pawlak, Joseph M.,Nayyar, Naresh K.,Dhokte, Ulhas P.,Doecke, Christopher W.,Zollars, Lisa M. H.,Moher, Eric D.,Khau, Vien Van,Kosmrlj, Berta
, p. 3578 - 3585 (2007/10/03)
This paper describes a convenient protocol for the regioselective sulfonylation of α-chelatable alcohols. Typically, the reaction of α-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 119Sn NMR studies.
Selective monosulfonylation of internal 1,2-diols catalyzed by di-n- butyltin oxide
Martinelli, Michael J.,Vaidyanathan, Rajappa,Van Khau, Vien
, p. 3773 - 3776 (2007/10/03)
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.
INTRINSIC MIGRATION APTITUDES OF ALKYL GROUPS IN A PINACOL REARRANGEMENT
Wistuba, Eckehardt,Ruechardt, Christoph
, p. 4069 - 4072 (2007/10/02)
From rates of solvolysis of substituted cis-2-tosyloxy-cyclopentanols 3 in sodium acetate buffered acetic acid the following relative migration aptitudes were deduced: H(171); CH3(6.7); C2H5(9.7); 2-C3H7(5.2); t-C4H9(2.5); C6H5(62).
