Cyclopropanation of Alkenes, N–H and S–H Insertion of Ethyl Diazoacetate Catalysed by Ruthenium Porphyrin Complexes
作者:Erwan Galardon、Paul Le Maux、Gérard Simonneaux
DOI:10.1016/s0040-4020(99)01050-9
日期:2000.1
Isomeric distribution for the cyclopropanation of isoprene and 1,3-pentadiene with ethyldiazoacetate and competition studies of the cyclopropanation and diazo insertion into heteroatom–hydrogen bonds are also reported. All these results agree with a major electronic and steric influence on both the regiochemical and stereochemical control in the catalytic cyclopropanation and diazo insertion reactions
Regio- and stereoselective cyclopropanation of functionalised dienes. Novel methodology for the synthesis of vinyl- and divinyl-cyclopropanes
作者:István E. Markó、Thierry Giard、Shinichi Sumida、Anne-Elisabeth Gies
DOI:10.1016/s0040-4039(02)00242-3
日期:2002.3
Dienes, bearing an electron-withdrawing substituent at C-1, are cyclopropanated regio- and stereo selectively at the C-C double bond proximal to this electron-withdrawing group. The highest selectivity is observed in the case of dienylboronates. The cyclopropanation of these substrates affords almost exclusively the synthetically useful 1-boronato-2-vinyl-cyclopropanes. (C) 2002 Elsevier Science Ltd. All rights reserved.
Recyclable Polymer- and Silica-Supported Ruthenium(II)-Salen Bis-pyridine Catalysts for the Asymmetric Cyclopropanation of Olefins
作者:Christopher S. Gill、Krishnan Venkatasubbaiah、Christopher W. Jones
DOI:10.1002/adsc.200800779
日期:2009.6
Abstractmagnified imageHomogeneous ruthenium(II)‐salen bis‐pyridine complexes are known to be highly active and selective catalysts for the asymmetric cyclopropanation of terminal olefins. Here, new methods of heterogenization of these Ru‐salen catalysts on polymer and porous silica supports are demonstrated for the facile recovery and recycle of these expensive catalysts. Activities, selectivities, and recyclabilities are investigated and compared to the analogous homogeneous and other supported catalysts for asymmetric cyclopropanation reactions. The catalysts are characterized with a variety of methods including solid state cross‐polarization magic‐angle spinning (CP MAS) 13C and 29Si NMR, FT‐IR, elemental analysis, and thermogravimetric analysis. Initial investigations produced catalysts possessing high selectivities but decreasing activities upon reuse. Addition of excess pyridine during the washing steps between cycles was observed to maintain high catalytic activities over multiple cycles with no impact on selectivity. Polymer‐supported catalysts showed superior activity and selectivity compared to the porous silica‐supported catalyst. Additionally, a longer, flexible linker between the Ru‐salen catalyst and support was observed to increase enantioselectivity and diastereoselectivity, but had no effect on activity of the resin catalysts. Furthermore, the polymer‐supported Ru‐salen‐Py2 catalysts were found to generate superior selectivities and yields compared to other leading heterogeneous asymmetric cyclopropanation catalysts.
An Efficient and Highly Enantio- and Diastereoselective Cyclopropanation of Olefins Catalyzed by Schiff-Base Ruthenium(II) Complexes We thank the reviewers for their helpful comments. Support from the DuPont Company and the Beckman, Dreyfus, and Packard Foundations are gratefully acknowledged. S.T.N. is an Alfred P. Sloan Fellow.