Construction of Chiral Quaternary Carbon through Morita-Baylis-Hillman Reaction: An Enantioselective Approach to 3-Substituted 3-Hydroxyoxindole Derivatives
作者:Xiao-Yang Guan、Yin Wei、Min Shi
DOI:10.1002/chem.201002240
日期:2010.12.10
A new enantioselectiveapproach to obtain a tetrasubstituted chiral center at the C3 position of oxindoles via a catalytic asymmetric Morita–Baylis–Hillmanreaction has been demonstrated. This reaction provides 3‐substituted 3‐hydroxy‐2‐oxindoles in good to excellent yields and ee values, which could be facilely transformed to pharmaceutically more interesting compounds.
Organocatalytic Enantioselective Mukaiyama–Mannich Reaction of Isatin‐Derived Ketimines for the Synthesis of Oxindolyl‐
<i>β</i>
<sup>3, 3</sup>
‐Amino Acid Esters
作者:Saumen Hajra、Sujay Laskar、Bibekananda Jana
DOI:10.1002/chem.201903512
日期:2019.11.18
Mukaiyama-Mannich reactions of ester enolate equivalents with aldimines have been elegantly used for the asymmetric synthesis of β-amino acids; nevertheless, the corresponding asymmetric reaction employing ketimines are unexplored. Herein, the first organocatalytic enantioselective Mukaiyama-Mannich reaction employing isatin-derived ketimines with unsubstituted silyl ketene acetals is disclosed towards
N-unprotected ketimines is realized for the first time by employing chiral BIBOP-type ligands with a Rh loading as low as 1 mol %. A range of chiral α-trifluoromethyl-α,α-diaryl α-tertiary amines or 3-amino-3-aryloxindoles were formed with excellent ee values and yields by employing either WingPhos or PFBO-BIBOP as the ligand. The method has enabled an efficient enantioselective synthesis of cipargamin
Enantioselective Alkynylation of Isatin Derivatives Using a Chiral Phase-Transfer/Transition-Metal Hybrid Catalyst System
作者:Suva Paria、Hyo-Jun Lee、Keiji Maruoka
DOI:10.1021/acscatal.8b04949
日期:2019.3.1
An enantioselective alkynylation of isatin derivatives can be realized by using a hybrid catalyst system consisting of chiral phase-transfer catalyst and transition-metal catalyst. The chiral alkynylation products can be used as versatile intermediates for further synthetic transformations.
Get selective! Enantioselective allylation of ketimines derived from isatins by using chiral 1,3‐bis(imidazolin‐2‐yl)benzene (Phebim)–PdII complexes afforded products with good enantioselectivity (see scheme). The reaction was applied to a wide variety of ketimines. The obtained product can be converted to homoallylic amines and a spirocyclic amine without the loss of enantiopurity.