Gold-Catalyzed [4C+2C] Cycloadditions of Allenedienes, including an Enantioselective Version with New Phosphoramidite-Based Catalysts: Mechanistic Aspects of the Divergence between [4C+3C] and [4C+2C] Pathways
作者:Isaac Alonso、Beatriz Trillo、Fernando López、Sergi Montserrat、Gregori Ujaque、Luis Castedo、Agustí Lledós、Jose L. Mascareñas
DOI:10.1021/ja905415r
日期:2009.9.16
Gold(I) complexes featuring electron acceptor ligands such as phosphites and phosphoramidites catalyze the [4C+2C] intramolecular cycloaddition of allenedienes. The reaction is chemo- and stereoselective, and provides trans-fused bicyclic cycloadducts in good yields. Moreover, using novel chiral phosphoramidite-based gold catalysts it is possible to perform the reaction with excellent enantioselectivity
Accept it! Although the π‐acceptor properties of N‐heterocyclic carbenes (NHCs) are often considered negligible, they can be enhanced to the extent that they start to dominate the catalytic behavior of gold–NHC complexes (see scheme). As it seems to be easier to tune the π acidity of NHCs than to alter their σ‐donor properties, the general perception of this important class of ancillary ligands needs
Gold-Catalyzed [4C+3C] Intramolecular Cycloaddition of Allenedienes: Synthetic Potential and Mechanistic Implications
作者:Beatriz Trillo、Fernando López、Sergi Montserrat、Gregori Ujaque、Luis Castedo、Agustí Lledós、Jose L. Mascareñas
DOI:10.1002/chem.200900164
日期:2009.3.23
room temperature: The Au complex generated in situ from [(IPr)AuCl] and AgSbF6 promotes the [4C+3C] intramolecularcycloaddition of allenes and dienes at room temperature, and in a particularly efficient and versatile manner. A DFT study on dimethylallenyl precursors agreed with the formation and cycloaddition of a metal–allyl cation intermediate, and points to the 1,2‐hydride shift as the key rate‐limiting
Mauleon, Pablo; Zeldin, Rachel M.; Gonzalez, Ana Z., Journal of the American Chemical Society, 2009, vol. 131, p. 6348 - 6349
作者:Mauleon, Pablo、Zeldin, Rachel M.、Gonzalez, Ana Z.、Toste, F. Dean
DOI:——
日期:——
Gold(I)-Catalyzed Enantioselective [4 + 2]-Cycloaddition of Allene-dienes
作者:Ana Z. González、F. Dean Toste
DOI:10.1021/ol902622b
日期:2010.1.1
An enantioselective gold(I)-catalyzed intramolecular [4 + 2]-cycloaddition of allenes and dienes is reported. The reactions allow for the asymmetric synthesis of trans-hexahydroindenes and pyrrolidine products using C3-symmetric phosphitegold(I) and ortho-arylphosphoramiditegold(I) complexes as catalysts, respectively.