Gold(I)-Catalyzed [2 + 2]-Cycloaddition of Allenenes
作者:Michael R. Luzung、Pablo Mauleón、F. Dean Toste
DOI:10.1021/ja075412n
日期:2007.10.1
A cationic phosphinegold(I)-catalyzed intramolecular [2 + 2]-cycloaddition between an allene and an alkene to form alkylidene−cyclobutanes is described. Additionally, the reported cycloisomerization reaction provides access to enantioenriched bicyclo-[3.2.0] structures using chiral biarylphosphinegold(I) complexes as catalysts.
Phosphoramidite Gold(I)-Catalyzed Diastereo- and Enantioselective Synthesis of 3,4-Substituted Pyrrolidines
作者:Ana Z. González、Diego Benitez、Ekaterina Tkatchouk、William A. Goddard、F. Dean Toste
DOI:10.1021/ja200084a
日期:2011.4.13
allenenes. A Au(I)-catalyzed synthesis of 3,4-disubstituted pyrrolidines and γ-lactams is described. This reaction proceeds through the enantioselective Au(I)-catalyzed cyclization of allenenes to form a carbocationic intermediate that is trapped by an exogenous nucleophile, resulting in the highly diastereoselective construction of threecontiguousstereogeniccenters. A computational study (DFT)
Readily available phosphoramidites incorporating TADDOL-related diols with an acyclic backbone turned out to be excellent ligands for asymmetric gold catalysis, allowing a number of mechanistically different transformations to be performed with good to outstanding enantioselectivities. This includes [2 + 2] and [4 + 2] cycloadditions of ene-allenes, cycloisomerizations of enynes, hydroarylation reactions
of an efficient synthesis of enantiopure phospha[6]helicenes through a [2+2+2] alkyne cyclotrimerization reaction. The corresponding gold complexes proved to be highly efficient both in terms of catalytic activity and enantioselectivity in [2+2] and [4+2] cycloaddition reactions. Furthermore, in the presence of an external nucleophile, such as water or alcohols, the tandem cyclization/addition reactions