Regioselective Alkylation of Carbohydrate Derivatives Catalyzed by a Diarylborinic Acid Derivative
作者:Lina Chan、Mark S. Taylor
DOI:10.1021/ol200990e
日期:2011.6.17
Regioselective, catalyst-controlled monoalkylations of cis-vicinal diol motifs in carbohydrate derivatives, using a diphenylborinic ester precatalyst, are described. Selective installation of benzyl, naphthylmethyl, 4-bromobenzyl and benzyloxymethyl protective groups at a single secondary hydroxy group of ten representative carbohydrate derivatives illustrates the scope of this method. This new mode
Novel benzoxaborole derivatives were designed as efficient catalysts for the highly site‐selective and protecting‐group‐free modification of polyols, such as carbohydrate. Additionally, the benzoxaborolecatalyst could tolerate diverse modifications of polyols, including acylation, sulfonylation, alkylation, and glycosylation.
An efficient one‐pot method for the selective benzylation of diols and polyols using 0.1 equiv. of organotin reagents and tetrabutylammonium bromide as catalyst has been developed. The diols and polyols containing a cis‐vicinal diol were regioselectively benzylated in 70–94% isolated yields. A catalytic reaction mechanism was also proposed.
9-Hetero-10-boraanthracene-derived borinic acid catalysts for regioselective activation of polyols
作者:Elena Dimitrijević、Mark S. Taylor
DOI:10.1039/c3sc51172c
日期:——
Heteraborinine-derived borinic acids serve as efficient catalysts for regioselective monofunctionalization of di- and polyols. Arylborinic acids of this type, wherein the B–OH group is incorporated into a 6π electron system, display both improved catalytic activity for functionalization of diols and enhanced stability towards air oxidation relative to the ‘parent’ diphenylborinic acid (Ph2BOH). These properties enable their applications at loadings as low as 0.1 mol% and without the need for a stabilizing precatalyst ligand (e.g., ethanolamine). Complexation studies, computation and kinetic data suggest that while the heteraborinine-derived borinic acids show significantly lower association constants with substrates than Ph2BOH, this effect is more than compensated for by the increased nucleophilicity of their tetracoordinate diol adducts.
Regio/site-selective alkylation of substrates containing a <i>cis</i>-, 1,2- or 1,3-diol with ferric chloride and dipivaloylmethane as the catalytic system
作者:Jian Lv、Yu Liu、Jia-Jia Zhu、Dapeng Zou、Hai Dong
DOI:10.1039/c9gc04126e
日期:——
In this study, we reported the regio/site-selective alkylation of substrates containing a cis-, 1,2- or 1,3-diol with FeCl3 as a key catalyst. A catalytic system consisting of FeCl3 (0.01–0.1 equiv.) and dipivaloylmethane (FeCl3/dipivaloylmethane = 1/2) was used to catalyze the alkylation in the presence of a base. The produced selectivities and isolated yields were similar to those obtained by methods