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.
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
Rhodium-catalyzed cycloisomerization of allenenes via metalacycle intermediates
作者:Tatsuya Makino、Kenji Itoh
DOI:10.1016/s0040-4039(03)01461-8
日期:2003.8
In the presence of a catalytic amount of the rhodium complex, allenenes undergo cycloisomerization reactions to result in the selective formation of five and seven membered exo-alkylidenecarbocycles and heterocycles via novel exo-alkylidenei-hodacyclopentane intermediates. (C) 2003 Elsevier Ltd. All rights reserved.