Modular Synthesis of Chiral Homo- and Heterotrisoxazolines. Improving the Enantioselectivity in the Asymmetric Michael Addition of Indole to Benzylidene Malonate
摘要:
A simple approach to a diverse set of chiral trisoxazolines is described. Deprotonation of bisoxazolines 2, followed by treatment of 2-chloromethyloxazolines 3, affords chiral trisoxazolines, including chiral homo- and hetero-trisoxazolines in good to high yields. These trisoxazolines are successfully applied in the asymmetric reaction of indole with benzylidene malonate, and ee's up to 93% were obtained.
Synthesis of Optically Active 2-Chloromethyl-2-oxazolines by the Ortho-ester Codensation Method Using Triethyl Orthochloroacetate
摘要:
A set of optically active 2-chloromethyl-2-oxazolines was synthesized by condensation of optically active 2-amino alcohols with triethyl orthochloroacetate which was prepared conveniently from triethyl orthoacetate by chlorination using tert-butyl hypochlorite.
ferrocene aminophosphoxazoline ligands (f-amphox) have been successfully developed and used in iridium-catalytic asymmetric hydrogenation of simpleketones to afford corresponding enantiomerically enriched alcohols under mild conditions with superb activities and excellent enantioselectivities (up to 1 000 000 TON, almost all products up to >99% ee, full conversion). The resulting chiral alcohols and their
Modification of Pseudo-C3-Symmetric Trisoxazoline and Its Application to the Friedel-Crafts Alkylation of Indoles and Pyrrole with Alkylidene Malonates
New pseudo-C3-symmetric hetero-trisoxazoline can be easily prepared on a gram scale in good yield. Its combination with copper(II) triflate exhibits high enantiomeric induction in the asymmetric Friedel-Crafts alkylation between indoles and alkylidene malonates, with up to 97% ee and good to excellent yields. The catalyst loading can be lowered to 0.5 mol% without loss of the enantiomeric excess.
Iridium-catalyzed asymmetric hydrogenation of <i>β</i>-keto esters with new phenethylamine-derived tridentate P,N,N-ligands
作者:De-Quan Wei、Xiu-Shuai Chen、Chuan-Jin Hou、Xiang-Ping Hu
DOI:10.1080/00397911.2018.1550203
日期:2019.1.17
Abstract A new class of phenethylamine-derived tridentate P,N,N-ligands has been successfully developed. These ligands exhibited good performance in the Ir-catalyzedasymmetric hydrogenation of β-keto esters, affording the corresponding β-hydroxy esters in moderate to good enantioselectivities. GRAPHICAL ABSTRACT
摘要 成功开发了一类新的苯乙胺衍生的三齿P,N,N-配体。这些配体在 Ir 催化的 β-酮酯不对称氢化中表现出良好的性能,以中等至良好的对映选择性提供相应的 β-羟基酯。图形概要
(4+3) Annulation of Donor‐Acceptor Cyclopropanes and Azadienes: Highly Stereoselective Synthesis of Azepanones
作者:Stefano Nicolai、Jérôme Waser
DOI:10.1002/anie.202209006
日期:2022.9.5
Azepanones are important and widespread seven-membered heterocycles, but their synthesis is challenging. A convergent method to access these scaffolds was developed relying on a (4+3) annulation reaction of azadienes and donor-acceptor cyclopropanes. Good to excellent yields and high diastereoselectivity were achieved using Yb(OTf)3 as the catalyst. Asymmetric induction was possible with Cu(OTf)2 in