The <sup>1</sup>H NMR Method for the Determination of the Absolute Configuration of 1,2,3-<i>p</i><i>rim</i>,<i>s</i><i>ec</i>,<i>s</i><i>ec-</i>Triols
作者:Enrique Lallana、Félix Freire、José Manuel Seco、Emilio Quiñoá、Ricardo Riguera
DOI:10.1021/ol0616135
日期:2006.9.1
comparison of the 1HNMR spectra of the tris-(R)- and the tris-(S)-MPA ester derivatives. An experimental demonstration of this correlation with 24 triols of known absolute configuration and a protocol using two parameters-Deltadelta(RS)(H3) and the difference between Deltadelta RS (H2) and Deltadelta RS (H3) = absolute value (Delta(Deltadelta RS))-for its application to the determination of the absolute
Chemoselective conversion of biologically sourced polyols into chiral synthons
作者:Laura L. Adduci、Trandon A. Bender、Jennifer A. Dabrowski、Michel R. Gagné
DOI:10.1038/nchem.2277
日期:2015.7
conversion of biomass into useful chemicals has often focused on either complete deoxygenation or the production of high-volume platform chemicals. Here, we describe the chemoselective partial reduction of silyl-protected C6O6-derived polyols to produce a diverse set of oxygen-functionalized chiral synthons. The combination of B(C6F5)3 and a tertiary silane efficiently generates a reactive equivalent of an
原油目前提供世界上大部分能源,但它也是许多原料化学品的来源。用于将生物质转化为有用化学物质的方法学通常集中在完全脱氧或大批量平台化学物质的生产上。在这里,我们描述了甲硅烷基保护的C 6 O 6衍生的多元醇的化学选择性部分还原,以产生各种不同的氧官能化手性合成子。B(C的组合6 ˚F 5)3和叔硅烷有效地产生亲电甲硅烷鎓离子(R的反应性等价物3的Si +)和氢化物(H -) 还原剂。氧损失的机理不涉及脱水消除,因此避免了立体化学的消融。相邻基团的参与和环状中间体的形成是在这些反应中实现选择性的关键,并且在同时存在伯和仲C-O键的情况下,该机理可以进一步控制。该方法在一个或两个合成步骤中提供了许多C 6 O n合成子以及几种先前未描述的产物的高度改进的合成方法。
Modulating Electrostatic Interactions in Ion Pair Intermediates To Alter Site Selectivity in the C−O Deoxygenation of Sugars
作者:Jared M. Lowe、Bekah E. Bowers、Youngran Seo、Michel R. Gagné
DOI:10.1002/anie.202007415
日期:2020.9.21
oligosaccharides. Computational methods helped identify this non‐intuitive outcome in low dielectric solvents to non‐isotropic electrostatic enhancements in the key ion pair intermediates, which influence the reaction coordinate in the reactivity‐/selectivity‐determining step. Molecular‐level models for these effects have far‐reaching consequences in stereoselective ion pair catalysis.
The asymmetric dihydroxylation of cis-allylic and homoallylic alcohols
作者:Michael S. VanNieuwenhze、K.Barry Sharpless
DOI:10.1016/s0040-4039(00)75978-8
日期:1994.1
The asymmetric dihydroxylation of several cis allylic alcohols is reported. The reactions proceed with moderate to good enantioselectivity. The enhanced enantioselection observed relative to other cis-olefin classes is believed to be dependent on the presence of the free hydroxyl group. A cis-homoallylic alcohol also gave a useful level of enantioselection in the AD.