Stereospecific inversion of secondary tosylates to yield chiral methyl-branched building blocks, applied to the asymmetric synthesis of leafminer sex pheromones
摘要:
All four of the possible stereoisomers of 5,9-dimethylheptadecane, the major sex pheromone component secreted by female moths of the mountain-ash bentwing (Leucoptera scitella), were synthesized by the coupling of two chiral blocks with a methyl branch at the 2- or 3-position. The blocks were prepared by applying the stereospecific inversion of secondary tosylates, which were derived from (R)- and (S)-propylene oxide, and their enantiopurities were confirmed by chiral HPLC analysis. (c) 2012 Elsevier Ltd. All rights reserved.
Enantioselective Transfer Hydrogenation of Aliphatic Ketones Catalyzed by Ruthenium Complexes Linked to the Secondary Face of β-Cyclodextrin
作者:Alain Schlatter、Wolf-D. Woggon
DOI:10.1002/adsc.200700558
日期:2008.5.5
Ruthenium-η-arene complexes attached to the secondary face of β-cyclodextrin catalyze the enantioselective reduction (ee up to 98%) of aliphatic and aromatic ketones in aqueous medium in the presence of sodium formate (HCOONa).
Chiral Surfactant-Type Catalyst for Asymmetric Reduction of Aliphatic Ketones in Water
作者:Jiahong Li、Yuanfu Tang、Qiwei Wang、Xuefeng Li、Linfeng Cun、Xiaomei Zhang、Jin Zhu、Liangchun Li、Jingen Deng
DOI:10.1021/ja308357y
日期:2012.11.14
A novel chiral surfactant-type catalyst is developed. Micelles formed in water by association of the catalysts themselves, and this was confirmed by TEM analyses. Asymmetric transfer hydrogenation of aliphaticketones catalyzed by the chiral metallomicellar catalyst gave good to excellent conversions and remarkable stereoselectivities (up to 95% ee). Synergistic effects between the metal-catalyzed
开发了一种新型手性表面活性剂型催化剂。通过催化剂本身的结合在水中形成胶束,这通过 TEM 分析得到证实。由手性金属胶束催化剂催化的脂肪族酮的不对称转移氢化具有良好到优异的转化率和显着的立体选择性(高达 95% ee)。金属催化中心与金属胶束中核心的疏水微环境之间的协同作用导致高对映选择性。
Chiral Surfactant-Type Catalyst: Enantioselective Reduction of Long-Chain Aliphatic Ketoesters in Water
ligands were designed and synthesized. The rhodium complexes with the ligands were applied to the asymmetric transfer hydrogenation of broad range of long-chained aliphatic ketoesters in neatwater. Quantitative conversion and excellent enantioselectivity (up to 99% ee) was observed for α-, β-, γ-, δ- and ε-ketoesters as well as for α- and β-acyloxyketone using chiral surfactant-type catalyst 2. The CH/π
Highly enantioselective reduction of ketones by chiral diol-modified lithium aluminum hydride reagents
作者:Yunlai Ren、Xinzhe Tian、Kunpeng Sun、Jian Xu、Xianlun Xu、Shijie Lu
DOI:10.1016/j.tetlet.2005.11.062
日期:2006.1
Some readily available chiral diols from indene and d-mannitol were investigated as chiral modifiers in lithiumaluminumhydridereduction of ketones, and it was discovered that further modification of these reducing reagents by a simple a-amino alcohol resulted in a remarkable increase in optical yield. Among the investigated chiral modifiers, chiral diol 1 gave the highest enantioselectivities.
observed in the reduction of hinderedketones such as isopropyl ketone, while the stereoselectivity was inverted in the reduction of ketones with electron-withdrawing atoms such as chlorine. The mechanism for the inversion in stereochemistry was investigated by enzymatic studies. Several enzymes with different stereoselectivities were isolated; one of them catalyzed the reduction of methyl ketones, and another