Microwave‐Assisted Rhodium‐Complex‐Catalyzed Cascade Decarbonylation and Asymmetric Pauson–Khand‐Type Cyclizations
作者:Hang Wai Lee、Lai Na Lee、Albert S. C. Chan、Fuk Yee Kwong
DOI:10.1002/ejoc.200800272
日期:2008.7
Microwave-assisted Rh–diphosphane-complex-catalyzed dual catalysis is reported. This cooperative process provides [2+2+1] cycloadducts by sequential decarbonylation of aldehyde or formate and carbonylation of enynes within a short period of time. Various O-, N-, and C-tethered enynes were transformed into the corresponding products in good yields. The first enantioselective version of this microwave-accelerated
Rh-Catalyzed Aqueous Pauson-Khand-Type Cycloaddition in Microwave-Irradiated Medium
作者:Fuk Kwong、Albert Chan、Hang Lee
DOI:10.1055/s-2008-1078413
日期:2008.6
Microwave-assisted Rh-catalyzed dual catalysis in aqueous medium is described. This tandem process transforms the enyne to cycloadduct by cascade decarbonylation of formate ester and subsequently carbonylation of enyne under microwave-irradiated conditions.
Rh(I)-Catalyzed Asymmetric Intramolecular Pauson-Khand Reaction in Aqueous Media
作者:Young Keun Chung、Won Hyuck Suh、Mira Choi、Sang Ick Lee
DOI:10.1055/s-2003-41044
日期:——
The first rhodium-BINAP complex-catalyzed enantioselective Pauson-Khand reaction in aqueous media, which is accelerated by surfactant, is reported. The chiral rhodium catalyst is easily prepared in situ from 1 equivalent of [Rh(cod)Cl]2 and 2 equivalents of BINAP under 1 atm of CO and a temperature of 60 °C or 90 °C. Ee’s up to 96% were achieved for the intramolecular Pauson-Khand reaction, but the yields are highly dependent upon the substrate itself.
Rh-Catalyzed Reductive Cyclization of Enynes Using Ethanol as a Source of Hydrogen
作者:Ji Hoon Park、Soo Min Kim、Young Keun Chung
DOI:10.1002/chem.201101745
日期:2011.9.19
H‐eartfelt donation: A Rh‐catalyzed reductivecyclization of unactivated 1,6‐enynes was developed that uses an alcohol as hydrogen donor under mild reaction conditions (see scheme). The reaction is an environmentally friendly synthetic method and proceeds efficiently to give various exo‐methylene‐substituted pyrrolidines, tetrahydrofuran, and cyclopentane compounds in a highly selective manner in moderate
A novel rhodium-catalyzed asymmetric intramolecular Pauson–Khandreaction using a chiral monophosphoramidite ligands is described. In this reaction, an in situ generated catalyst from [Rh(CO)2Cl]2, the spiro-monophosphoramidite ligand SIPHOS and AgSbF6 was found to be effective for a series of 1,6-enynes, providing the co-cyclization products in good enantioselectivities (84% ee).