Palladium-Catalyzed Stereospecific Decarboxylative Benzylation of Alkynes
摘要:
Enantioenriched benzyl esters of propiolic acids undergo highly stereospecific decarboxylative coupling to provide 1,1-diarylethynyl methanes. This sp-sp(3) coupling does not require strongly basic conditions or preformed organometallics and produces CO2 as the sole byproduct. Ultimately, this method results in the successful transfer of stereochemical information from secondary benzyl alcohols to generate enantioenriched tertiary diarylmethanes.
New C2-symmetric tetrafluorobenzobarreleneligands were prepared and applied successfully to the rhodium-catalyzedasymmetric addition of arylboronic acids to aromatic aldehydes giving chiral diarylmethanols in high yield with high enantioselectivity.
Predicted outcomes: The additionreaction of organoboronicacids with aldehydes in the presence of K2CO3 catalyzed by CoI2/(R,R)‐BDPP gives chiral secondary alcohols in excellent yields with 90–99 % enantiomeric excess (see scheme; (R,R)‐BDPP=(2R,4R)‐(+)‐2,4‐bis(diphenylphosphino)pentane). This method provides an alternative to prepare an R and S enantiomeric pair by using the same chiral ligand and
预期的结果:在CoI 2 /(R,R)-BDPP催化下,在存在K 2 CO 3的情况下,有机硼酸与醛的加成反应可得到出色的手性仲醇,对映体过量90-99%(参见方案;(R,R)-BDPP =(2 R,4 R)-(+)-2,4-双(二苯基膦基)戊烷)。该方法提供了另一种通过使用相同的手性配体制备R和S对映体对的方法,并且可以预测反应的立体化学结果。
Asymmetric Hydrophosphination of Heterobicyclic Alkenes: Facile Access to Phosphine Ligands for Asymmetric Catalysis
作者:Zhiwu Lu、Haoyang Zhang、Zhiping Yang、Ning Ding、Ling Meng、Jun Wang
DOI:10.1021/acscatal.8b04787
日期:2019.2.1
Asymmetric hydrophosphination is the most atomically economical and straightforward approach to the construction of chiral organophosphorus compounds. Good stereoselectivities have been achieved in asymmetric hydrophosphination of an electron-deficient C═C double bond, but substrates involving nonpolar C═C bonds remain difficult and are rarely tackled. Herein, we report asymmetric hydrophosphination
Highly Enantioselective Addition of In Situ Prepared Arylzinc to Aldehydes Catalyzed by a Series of Atropisomeric Binaphthyl-Derived Amino Alcohols
作者:Gui Lu、Fuk Yee Kwong、Ji-Wu Ruan、Yue-Ming Li、Albert S. C. Chan
DOI:10.1002/chem.200501048
日期:2006.5.15
catalyst, both enantiomers of many pharmaceutically interesting diarylmethanols can be obtained by the proper combination of various arylzinc reagents with different aldehydes; this catalytic system also works well for the phenylation of aliphatic aldehydes to give up to 96 % ee.
Asymmetric diethylzinc addition and phenyl transfer to aldehydes using chiral cis-cyclopropane-based amino alcohols
作者:Jiangchun Zhong、Hongchao Guo、Mingan Wang、Mingming Yin、Min Wang
DOI:10.1016/j.tetasy.2007.03.006
日期:2007.4
A new series of aminoalcohols with a chiral cyclopropane backbone have been developed and used in the catalytic asymmetric diethylzinc addition and phenyl transfer to various types of aldehydes. These cyclopropane-based chiral aminoalcohols show high enantioselectivity in the addition of organozincs to aromatic and aliphatic aldehydes. For diethylzinc addition to aromatic and aliphatic aldehydes