The pinacol coupling is one of the most significant methods to synthesize vic-diols. The combination of samarium diiodide (SmI2) and samarium metal successfully induces the selective pinacol couplings of not only aromatic aldehydes and ketones but also aliphatic ones in the presence of trimethylchlorosilane (Me3SiCl) in 1,2-dimethoxyethane (DME). DME is the most suitable solvent for the reduction system
An imidazolium-modified chiral rhodium/diamine-functionalized periodic mesoporous organosilica for asymmetric transfer hydrogenation of α-haloketones and benzils in aqueous medium
作者:Feng Zhou、Xiaoying Hu、Ming Gao、Tanyu Cheng、Guohua Liu
DOI:10.1039/c6gc01589a
日期:——
Use of a hydrophobic, imidazolium-functionalized periodicmesoporousorganosilica for immobilizations of chiral organometalliccomplexes as a heterogeneouscatalyst is a highly desirable as this catalyst can promote greatly an aqueous...
Stereoselective Barbier-Type Allylations and Propargylations Mediated by CpTiCl<sub>3</sub>
作者:Josefa L. López-Martínez、Irene Torres-García、Ignacio Rodríguez-García、Manuel Muñoz-Dorado、Miriam Álvarez-Corral
DOI:10.1021/acs.joc.8b02643
日期:2019.1.18
CpTiCl2, prepared in situ by manganese reduction of CpTiCl3, is an excellent new system for the Barbier-typeallylation and propargylation of carbonyl compounds. It can be used in catalytic amounts when combined with Et3N·HBr/TMSBr, which acts as a regenerating system. The high regio- and stereoselectivity shown by this system makes it useful for prenylation and crotylation processes in the synthesis
Reductive Coupling of Carbonyl Compounds to Pinacols with Zinc in THF-Saturated Aqueous Ammonium Chloride
作者:Rahim Hekmatshoar、Issa Yavari、Yahya S. Beheshtiha、Majid M. Heravi
DOI:10.1007/s007060170083
日期:2001.6
In the presence of metallic zinc, aldehydes and ketones experience reductive coupling in tetrahydrofuran-saturated aqueousammoniumchloride (5:3) to afford the corresponding pinacols in moderate to high yields.
aromatic carbonylcompounds were carried out using an 80% [BMIM][BF4]–H2O mixture as the electrolytic medium. The corresponding diols were obtained in good to excellent yields with moderate diastereoselectivity. The stereoselectivity can be explained using the strongly-bound ion-pairs formed between the imidazolium cation and the radical anions of the carbonylcompounds. The ionicliquid replaces both