Enantioselective Henry reaction catalyzed with copper(II)–iminopyridine complexes
作者:Gonzalo Blay、Estela Climent、Isabel Fernández、Victor Hernández-Olmos、José R. Pedro
DOI:10.1016/j.tetasy.2007.06.023
日期:2007.7
Coppercomplexes of chiral iminopyridines prepared from camphane-derived ketones and picolylamine catalyzed the enantioselectiveHenry (nitroaldol) reaction between nitromethane and a number of aromatic and aliphatic aldehydes with high yields and good enantioselectivities. Iminopyridines derived from (1R)-(+)-camphor and (1S)-(+)-ketopinic acid gave the best results to afford the opposite enantiomers
to 90 % ee. The method was applied to the continuous‐flow synthesis of biologically active chiral 1,2‐amino alcohols (norephedrine, metaraminol, and methoxamine) through a two‐step sequence combining the nitroaldol reaction with a hydrogenation. To highlight potential industrial applications of this method, a multistep continuous synthesis of norephedrine has been realized. The product was isolated
Synthesis and application of new iminopyridine ligands in the enantioselective palladium-catalyzed allylic alkylation
作者:Maurizio Solinas、Barbara Sechi、Giorgio Chelucci、Salvatore Baldino、José R. Pedro、Gonzalo Blay
DOI:10.1016/j.molcata.2014.01.006
日期:2014.4
A variety of iminopyridines were obtained by condensation of chiral amines with pyridine-2-carboxaldehyde and quinoline-8-carbaldehyde, or of aminoalkylpyridine derivatives with chiral ketones. These ligands were assessed in the enantioselective palladium catalyzed allylic substitution of 1,3-diphenylprop-2-enyl acetate with dimethyl malonate affording the product dimethyl 1,3-diphenylprop-2-enylmalonate
Decoding the Mechanism of Intramolecular Cu-Directed Hydroxylation of sp<sup>3</sup> C–H Bonds
作者:Rachel Trammell、Yi Yang See、Aaron T. Herrmann、Nan Xie、Daniel E. Díaz、Maxime. A. Siegler、Phil S. Baran、Isaac Garcia-Bosch
DOI:10.1021/acs.joc.7b01069
日期:2017.8.4
the reaction conditions to oxidize similar substrates with excellent yields. In both reports, the involvement of Cu2O2 intermediates was suggested. In this collaborative article, we studied the hydroxylation mechanism in great detail, resulting in the overhaul of the previously accepted mechanism and the development of improved reaction conditions. Extensive experimental evidence (spectroscopic characterization
铜在定向C–H氧化中的使用尚未得到充分研究。在一个开创性的例子中,Schönecker表明铜和O 2促进了含有类固醇的配体的羟基化。最近,巴兰(J.化学会会志。2015,137,13776)改善了反应条件,以氧化类似底材具有优良的产率。在这两个报告中,Cu 2 O 2的参与建议使用中间体。在这篇合作文章中,我们对羟基化机理进行了详细的研究,从而对先前公认的机理进行了全面的改进,并开发了改进的反应条件。提供了广泛的实验证据(光谱表征,动力学分析,分子间反应性和自由基捕集实验),以支持提出的每个基本步骤,并假设关键的单核LCu II(OOR)中间体会经历均相O-O裂解以产生反应性的假设。• RO •物种,负责溶剂笼内的关键C–H羟基化。这些关键发现使氧化方案得以重新制定,从而提高了反应成本,实用性和分离的收率。
Scalable C–H Oxidation with Copper: Synthesis of Polyoxypregnanes
作者:Yi Yang See、Aaron T. Herrmann、Yoshinori Aihara、Phil S. Baran
DOI:10.1021/jacs.5b09463
日期:2015.11.4
Steroids bearing C12 oxidations are widespread in nature, yet only one preparative chemical method addresses this challenge in a low-yielding and not fully understood fashion: Schonecker's Cu-mediated oxidation. This work shines new light onto this powerful C-H oxidation method through mechanistic investigation, optimization, and wider application. Culminating in a scalable, rapid, high-yielding, and operationally simple protocol, this procedure is applied to the first synthesis of several parent polyoxypregnane natural products, representing a gateway to over 100 family members.