Synthesis and Application of Phosphinoferrocenylaminophosphine Ligands for Asymmetric Catalysis
摘要:
[GRAPHICS]A new class of bidentate ligands utilizing a phosphine-aminophosphine structure has been prepared on a ferrocenylethyl backbone in a straightforward and scalable fashion from acetylferrocene. The unique property of the alpha-ferrocenyl carbonium ion that allows the replacement of a variety of "leaving groups" with retention of configuration greatly facilitates the synthesis, and a number of ligands have been prepared by varying the nitrogen and phosphorus substituents on the aminophosphine. These readily prepared phosphinoferrocenylaminophosphines, known as BoPhoz ligands, show surprising hydrolytic and air stability, with no degradation after 3 years open to the air. The rhodium complexes of these ligands show exceedingly high enantioselectivities (generally >95% ee) and activities often in excess of 50 000 catalyst turnovers per hour for the asymmetric hydrogenation of a wide variety of dehydro-alpha-amino acid and itaconic acid derivatives. They also show high activity and good to excellent enantioselectivity for the hydrogenation of a number of alpha-ketoesters.
Asymmetric Synthesis of β,β-Disubstituted Alanines via a Sequential C(sp2)–C(sp3) Cross-Coupling–Hydrogenation Strategy
作者:David A. Petrone、Jonathan Maturano、James Herbort、Erin E. Plasek、J. Mayeli Vivaldo-Nikitovic、David Sarlah
DOI:10.1021/acs.orglett.4c02376
日期:2024.7.26
allows access to a diverse array of valuable β,β-disubstituted alanine derivatives. This synthesis exhibits broad functional group tolerance, and permits efficient access to β-aryl-β-alkyl, and the more rarely reported β,β-dialkyl Ala derivatives with high yield and excellent enantioselectivity. This transformation has been exhibited on decagram quantity, and can be used to generate Fmoc aminoacid derivatives
Solvent-free synthesis of unsaturated amino esters in a ball-mill
作者:Alice Baron、Jean Martinez、Frédéric Lamaty
DOI:10.1016/j.tetlet.2010.09.069
日期:2010.12
The ball-milling technique was used under solvent-free conditions to perform a Horner-Wadsworth-Emmons reaction in the presence of a mild carbonate base. Starting from a phosphonate-substituted glycine, this method gave access to Boc-protected unsaturated amino esters in excellent yield and selectivity in many cases. The scope of the reaction was delineated. (C) 2010 Elsevier Ltd. All rights reserved.
Copper-Catalyzed Asymmetric Hydroboration of α-Dehydroamino Acid Derivatives: Facile Synthesis of Chiral β-Hydroxy-α-amino Acids
作者:Zhi-Tao He、Yi-Shuang Zhao、Ping Tian、Chuan-Chuan Wang、Han-Qing Dong、Guo-Qiang Lin
DOI:10.1021/ol500219e
日期:2014.3.7
The Cu-catalyzed asymmetric conjugate hydroboration reaction of beta-substituted alpha-dehydroamino acid derivatives has been established, affording enantioenriched syn- and anti-beta-boronate-alpha-amino acid derivatives with excellent combined yields (83-99%, dr approximate to 1:1) and excellent enantioselectivities (92-98% ee). The hydroboration products were expediently converted into valuable beta-hydroxy-alpha-amino acid derivatives, which were widely used in the preparation of chiral drugs and bioactive molecules.