The successful example of chiral formamides that function as asymmetriccatalysts is described. (S,S)-N,N-Bis(α-methylbenzyl)formamide mediates the enantioselective addition of allyl- and crotyltrichlorosilanes to aliphatic aldehydes with the assistance of hexamethylphosphoramide (HMPA) to afford the corresponding homoallylic alcohols in up to 98% enantiomeric excess.
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
Photocatalytic Umpolung Synthesis of Nucleophilic π-Allylcobalt Complexes for Allylation of Aldehydes
作者:Caizhe Shi、Fusheng Li、Yuqing Chen、Shuangjie Lin、Erjun Hao、Zhuowen Guo、Urwa Tul Wosqa、Dandan Zhang、Lei Shi
DOI:10.1021/acscatal.0c05330
日期:2021.3.5
method for the allylation of aldehydes. This paper describes the photocatalytic umpolung strategy for the synthesis of nucleophilic allylcobalt complexes through a single-electron-transfer (SET) process. This strategy enables the metallaphotoredox allylation of carbonyls with allyl acetate using organic N,N-diisopropylethylamine as the terminal reductant bypassing the use of a stoichiometric amount of
Enantioselective (8+3) Cycloadditions by Activation of Donor–Acceptor Cyclopropanes Employing Chiral Brønsted Base Catalysis
作者:David A. McLeod、Mathias Kirk Thøgersen、Casper Larsen Barløse、Mette Louise Skipper、Erlaitz Basabe Obregón、Karl Anker Jørgensen
DOI:10.1002/anie.202206096
日期:2022.7.18
A non-covalent organocatalytic enantioselective (8+3) cycloaddition of donor–acceptorcyclopropanes and heptafulvenoids is reported. The reaction design employs an anionic cyclopropane activation strategy by employing a bifunctional optically-active Brønsted base. The reaction pathway and mechanism of stereochemical control was investigated by DFT calculations.
Radical homopolymerization of linear α-olefins has been developed. The success of this polymerization relies on the high efficiency of 1,4-cyano group migration. This approach can be applied to homopolymerize α- substituted styrenes or acrylates. As a chain transfer agent, a symmetric allylic sulfide is created to regulate the propagating thiyl radicals over the polymerization process.