Metal-Free Catalytic Boration at the β-Position of α,β-Unsaturated Compounds: A Challenging Asymmetric Induction
作者:Amadeu Bonet、Henrik Gulyás、Elena Fernández
DOI:10.1002/anie.201001198
日期:——
Enantiomerically enriched secondary organoboronates containing β‐carbonyl functional groups have been prepared using an unprecedented organocatalytic system (see scheme). The use of chiral tertiary phosphorus compounds induced ee values of up to 95 % in the absence of transition metals.
Axially chiral P-N ligands for the copper catalyzed β-borylation of α,β-unsaturated esters
作者:William J. Fleming、Helge Müller-Bunz、Vanesa Lillo、Elena Fernández、Patrick J. Guiry
DOI:10.1039/b900741e
日期:——
The synthesis and resolution of a new axially chiral Quinazolinap ligand are reported. The application of this and other related P-N ligands to the copper catalyzed β-borylation of α,β-unsaturated esters resulted in conversions of up to 100% and ee values of up to 79%. A diastereomerically pure palladacycle of the new ligand was characterised by X-ray crystallography.
Synthesis of Novel Diastereomeric Diphosphine Ligands and Their Applications in Asymmetric Hydrogenation Reactions
作者:Liqin Qiu、Jianying Qi、Cheng-Chao Pai、Shusun Chan、Zhongyuan Zhou、Michael C. K. Choi、Albert S. C. Chan
DOI:10.1021/ol026817+
日期:2002.12.1
Diastereomeric biaryl diphosphine ligands 10 and 11 with added chiral centers on the backbone were synthesized. Substrate-directed asymmetricsynthesis occurred in the coupling step of the preparation of the diastereomeric diphosphine oxides. The diastereomeric diphosphine oxides were easily separated by column chromatography with silica gel. Ruthenium catalysts containing these ligands were highly effective
Inversion of secondary chiral alcohols in toluene with the tunable complex of R3NR′COOH
作者:Xiao-Xin Shi、Chun-Li Shen、Jian-Zhong Yao、Liang-Deng Nie、Na Quan
DOI:10.1016/j.tetasy.2009.12.028
日期:2010.3
The S(N)2 reaction of enantiomerically pure sulfonates with the tunable complex of R3N-R'COOH in toluene has been extensively studied. It was revealed that the molar ratio of the tertiary amines and carboxylic acids in the complex of R3NR'COOH is crucial for the S(N)2 reaction, and should be tuned for each sulfonate to give the best yield. Fifteen sulfonates 1 and 3-13 (Scheme 2) were prepared and transformed into 22 corresponding inverted esters 2 and 14-24 (Scheme 2) in good to high yields. (C) 2010 Elsevier Ltd. All rights reserved.