Iridium‐Catalyzed Enantioselective Hydrogenation of Vinylsilanes
作者:Aie Wang、Maurizio Bernasconi、Andreas Pfaltz
DOI:10.1002/adsc.201700162
日期:2017.8.7
iridium complexes derived from chiral N,P ligands as catalysts for the asymmetric hydrogenation of vinylsilanes, a transformation for which generally applicable catalysts were lacking. Several catalysts emerged from this study that enabled the highly enantioselective hydrogenation of a wide range of vinylsilanes with trisubstituted or disubstituted terminal C=C bonds bearing aryl, alkyl, ethoxycarbonyl,
Fluorodesilylation of alkenyltrimethylsilanes: a new route to fluoroalkenes and difluoromethyl-substituted amides, alcohols or ethers
作者:Benjamin Greedy、Veronique Gouverneur
DOI:10.1039/b009179k
日期:——
A range of alkenyltrimethylsilanes are converted to alkenyl
fluorides by reaction with one equivalent of Selectfluor™
(1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane
bis(tetrafluoroborate)), or difluoromethyl-substituted alcohols, ethers or
amides using an excess of Selectfluor™ in the presence of
various nucleophiles.
The contra-thermodynamic E→Zisomerization of vinyl silanes was reported using rac-BINAP as the photocatalyst. This reaction proceeds via the in situ formation of a chromophoric species, in the presence of catalyst. Under irradiation at 405 nm the interconversion of E-isomers into the Z-congeners were carried out in good to excellent yields and outstanding Z/E selectivities (18 examples) and the reaction
The addition of dialkylzincs or diphenylzinc to substituted phenylacetylenes in the presence of catalytic amounts of Ni(acac)(2) in THF : NMP mixtures produces syn-carbozincation products with good to excellent regio-and stereoselectivity. After quenching with an electrophile (iodine, acyl chloride, allyl bromide) tetrasubstituted olefines are obtained in good to satisfactory yields. An intramolecular version of the reaction is possible using a terminal triple bond bearing an iodine at a remote position. More substituted iodo-alkynes furnish only reductive elimination products. An application to a stereoselective synthesis of (Z)-tamoxifen (Z: E > 99: 1) has been developed. (C) 1998 Elsevier Science Ltd. All rights reserved.
Wong, Ken-Tsung; Ni, Zhi-Jie; Luh, Tien-Yau, Journal of the Chemical Society. Perkin transactions I, 1991, # 12, p. 3113 - 3116