Kinetic Resolution of Tertiary Alcohols: Highly Enantioselective Access to 3-Hydroxy-3-Substituted Oxindoles
作者:Shenci Lu、Si Bei Poh、Woon-Yew Siau、Yu Zhao
DOI:10.1002/anie.201209043
日期:2013.2.4
Enantioselective: The first highlyenantioselectivekineticresolution of 3‐hydroxy‐3‐substituted oxindoles has been developed through oxidative esterification catalyzed by a N‐heterocyclic carbene (see picture). This method uses a simple procedure and provides 3‐hydroxy‐oxindoles with various substituents at the 3‐position in excellent enantiopurity. S=selectivity.
Chiral CNN Pincer Palladium(II) Complexes with 2-Aryl-6-(oxazolinyl)pyridine Ligands: Synthesis, Characterization, and Application to Enantioselective Allylation of Isatins and Suzuki–Miyaura Coupling Reaction
作者:Tao Wang、Xin-Qi Hao、Juan-Juan Huang、Kai Wang、Jun-Fang Gong、Mao-Ping Song
DOI:10.1021/om400945d
日期:2014.1.13
1-naphthyl) ligands 2a–f were conveniently prepared from commercially available 6-bromo-2-picolinaldehyde in two steps. Reaction of 2a–f with PdCl2 in toluene in the presence of sodium bicarbonate afforded the corresponding CNNpincer Pd(II) complexes 3a–f via aryl C–H bond activation of the related ligands. All of the new compounds have been fully characterized by elemental analysis (MS for ligands), 1H
The asymmetric synthesis of the 3-allyl-3-hydroxyoxindole skeleton was accomplished in yields up to 99% via a metal-free and enantioselective allylation of isatins (90–96% ee) using BINOL derivatives as catalysts and an optimized allylboronate. This methodology was applied at a gram-scale to the synthesis of the natural product (R)-chimonamidine.