2-Aryl propionamides via 1,4-aryl radical migration from N-arylsulfonyl-2-bromopropionamides
摘要:
Reaction of N-alkyl-N-arylsulfonyl-2-halo-propionamides with pentamethyldiethylenetriamine and either CuBr or CuCl leads to 2-aryl propionamides via initial radical generation, 1,4-aryl migration with loss of SO2 and reduction of the intermediate amidyl radical in 40-99% yields. (C) 2009 Elsevier Ltd. All rights reserved.
The present invention relates to chiral metal catalysts for stereoselective olefin metathesis reactions, which are recyclable and reusable in such metathesis reactions. The chiral metal-based metathesis catalysts of the invention comprise multidentate optically active or racemic chiral ligands that enable their use in asymmetric synthetic processes, such as for example, in ring-opening and ring-closing metathesis reactions (ROM and RCM, respectively) of alkenes. The catalysts of the invention are organometallic complexes of multivalent metals comprising one or more chiral bidentate ligands that exhibit superior reactivity and stereoselectivity properties. The present invention also provides methods of making such catalysts and methods for utilizing them in catalyzing stereoselective olefin metathesis reactions to provide asymmetric products in relatively high enantiomeric or stereoisomeric excess.
A Recyclable Chiral Ru Catalyst for Enantioselective Olefin Metathesis. Efficient Catalytic Asymmetric Ring-Opening/Cross Metathesis in Air
作者:Joshua J. Van Veldhuizen、Steven B. Garber、Jason S. Kingsbury、Amir H. Hoveyda
DOI:10.1021/ja020259c
日期:2002.5.1
a new chiral bidentate imidazolinylidene ligand and a derived chiral Ru-based carbene are disclosed. The Ru complex is stereogenic at the metal center; it can be prepared in >98% diastereoselectivity and purified by silica gel chromatography with undistilled solvents. The air-stable Ru complex efficiently catalyzes ring-closing and ring-opening metathesis and is recyclable. The chiralcomplex is highly
Mesocellular Foam-Supported Catalysts: Enhanced Activity and Recyclability for Ring-Closing Metathesis
作者:Jaehong Lim、Su Seong Lee、Siti Nurhanna Riduan、Jackie Y. Ying
DOI:10.1002/adsc.200600442
日期:2007.5.7
siliceous mesocellular foam (MCF). The open and interconnected pores of MCF facilitated ligand immobilization and substrate diffusion. We have observed that the ligand and metal loadings significantly affected the catalytic activity and recyclability. Enhancedrecyclability by suppression of ruthenium leaching was achieved by using excess immobilized ligands. The resulting novel heterogenized catalysts demonstrated
Efficient and Recyclable Monomeric and Dendritic Ru-Based Metathesis Catalysts
作者:Steven B. Garber、Jason S. Kingsbury、Brian L. Gray、Amir H. Hoveyda
DOI:10.1021/ja001179g
日期:2000.8.1
bearing a 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene and styrenyl etherligand is disclosed. The heterocyclic ligand significantly enhances the catalytic activity, and the styrenyl ether allows for the easy recovery of the Ru complex. Catalyst 5 promotes ring-closing metathesis (RCM) and the efficient formation of various trisubstituted olefins at ambient temperature in high yield within 2 h; the catalyst