A nickel-catalyzed carbozincation of aryl-substituted alkynes
摘要:
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.
Ruthenium Catalyzed Diastereo- and Enantioselective Coupling of Propargyl Ethers with Alcohols: Siloxy-Crotylation via Hydride Shift Enabled Conversion of Alkynes to π-Allyls
作者:Tao Liang、Wandi Zhang、Te-Yu Chen、Khoa D. Nguyen、Michael J. Krische
DOI:10.1021/jacs.5b08019
日期:2015.10.14
The first enantioselective carbonyl crotylations through direct use of alkynes as chiral allylmetal equivalents are described. Chiral ruthenium(II) complexes modified by Josiphos (SL-J009-1) catalyze the C-C coupling of TIPS-protected propargyl ether 1a with primary alcohols 2a-2o to form products of carbonyl siloxy-crotylation 3a-3o, which upon silyl deprotection-reduction deliver 1,4-diols 5a-5o
Magnesium-Catalyzed Stereoselective Hydrostannylation of Internal and Terminal Alkynes
作者:Marc Magre、Marcin Szewczyk、Magnus Rueping
DOI:10.1021/acs.orglett.0c00184
日期:2020.2.21
A regio- and stereoselective magnesium-catalyzed hydrostannylation of internal and terminalalkynes has been developed. Excellent yields and selectivities are obtained for a wide range of terminal and internal symmetrical and unsymmetrical alkynes by using this alkaline earth metal catalyst as an effective alternative to transition metal catalysts.
Rhodium(III)-Catalyzed Arene and Alkene C−H Bond Functionalization Leading to Indoles and Pyrroles
作者:David R. Stuart、Pamela Alsabeh、Michelle Kuhn、Keith Fagnou
DOI:10.1021/ja1082624
日期:2010.12.29
formation of indoles via the oxidative annulation of acetanilides with internal alkynes. The optimized reaction conditions allow for molecular oxygen to be used as the terminal oxidant in this process, and the reaction may be carried out under mild temperatures (60 °C). These conditions have resulted in an expanded compatibility of the reaction to include a range of new internal alkynes bearing synthetically
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.
On the Hydrostannylation of Aryl Propargylic Alcohols and Their Derivatives: Remarkable Differences in Both Regio- and Stereoselectivity in Radical- and Nonradical-Mediated Transformations
作者:Martins S. Oderinde、Robert D. J. Froese、Michael G. Organ
DOI:10.1002/chem.201403459
日期:2014.7.7
Herein, we describe a highly regio‐ and stereoselective radical‐mediated and molecular‐oxygen (O2)‐dependent hydrostannylation of phenyl propargylicalcohols and their derivatives. There is a significant steric effect on the stereoselectivity of the tin‐radical addition. Further, the uncatalyzed regio‐ and stereoselectivehydrostannylation of arylpropargylicalcohols with nBu3SnH and Ph3SnH is also described
本文中,我们描述了苯丙炔醇及其衍生物的高度区域选择性和立体选择性的自由基介导和分子氧(O 2)依赖性加氢苯乙烯基化反应。锡自由基加成物的立体选择性有很大的空间效应。此外,还描述了芳基炔丙醇与n Bu 3 SnH和Ph 3 SnH的未催化区域和立体选择性加氢苯乙烯基化反应,并以接近滴定的动力学发生。尽管不考虑芳基部分的电子性质,n Bu 3 SnH的未催化加成反应均具有显着的γ-区域选择性,但Ph 3的加成反应SnH似乎是由芳基炔烃的电子性质驱动的。