The regioselectivity of insertion of carbenoids into a variety of unsymmetrical zirconacyclopentanes is reported. For comparison the regioselectivities of isonitrile insertion and protonation have also been determined. (c) 2007 Elsevier Ltd. All rights reserved.
Investigations concerning the organolanthanide and group 3 metallocene-catalyzed cyclization–functionalization of nitrogen-containing dienes
摘要:
Organolanthanide catalyzed cyclization-silylation of nitrogen-containing polyunsaturated systems allows access to core structures commonly found in naturally occurring alkaloids. Nitrogen-containing dienes with various substitution patterns were investigated. The method was most successful for substrates with terminal alkenes. Cyclization upon pendant 1,1-disubstituted olefins was not realized under various conditions. Interestingly, sterically hindered sulfonamides, which were previously believed to render the catalyst inactive, were actually compatible with the catalyst, thus affording the cyclized products after prolonged reaction times. Variations using fused ring systems were also investigated. (C) 2005 Elsevier Ltd. All rights reserved.
Tandem Insertion of Halocarbenoids and Lithium Acetylides into Zirconacycles: A Novel Rearrangement to Zirconium Alkenylidenates by β-Addition to an Alkynyl Zirconocene
作者:Jozef Stec、Emma Thomas、Sally Dixon、Richard J. Whitby
DOI:10.1002/chem.201002962
日期:2011.4.18
Tandem insertion of 1,1‐dihalo‐1‐lithio species (halocarbenoids) and lithium alkynides into zirconacyclopentenes and zirconcyclopentanes affords carbocyclic products in high yields via an unusual rearrangement that probably involves addition of an organolithium species to the β‐position of a zirconium–alkyne complex to give an alkenylidene–zirconate species. A wide variety of cyclopentanoid organic
The Regiochemistry of Carbenoid Insertion into Zirconacycles
作者:George J. Gordon、Tim Luker、Mark W. Tuckett、Richard J. Whitby
DOI:10.1016/s0040-4020(99)01094-7
日期:2000.4
lithium chloroallylides (allyl carbenoids) into a wide variety of unsymmetrical zirconacycles has been determined. In all but one case a single regioisomer was obtained. A combination of steric and electronic effects is needed to explain the results and imply that the carbenoid is acting predominantly as an electrophilic species. The first carbenoid insertion into a zirconacyclopentadiene is noted.
Pyrrole synthesis using a tandem Grubbs’ carbene–RuCl3 catalytic system
作者:Nicolai Dieltiens、Christian V. Stevens、David De Vos、Bart Allaert、Renata Drozdzak、Francis Verpoort
DOI:10.1016/j.tetlet.2004.10.044
日期:2004.11
A straightforward pyrrole synthesis from diallylamines is developed by using a tandem catalyst system leading to ring-closing metathesis with the second generation Grubbs' catalyst (10%) followed by dehydrogenation in the presence of RuCl3 x H2O (2%). (C) 2004 Elsevier Ltd. All rights reserved.
Fu, Gregory C.; Grubbs, Robert H., Journal of the American Chemical Society, 1992, vol. 114, # 18, p. 7324 - 7325
作者:Fu, Gregory C.、Grubbs, Robert H.
DOI:——
日期:——
Synthesis of Heterocycles Using Zirconium-Catalyzed Asymmetric Diene Cyclization