77517-64-7Relevant academic research and scientific papers
Pd-catalyzed allylic substitution using nucleophilic N-heterocyclic carbene as a ligand
Sato, Yoshihiro,Yoshino, Taro,Mori, Miwako
, p. 31 - 33 (2003)
(Matrix presented) A nucleophilic N-heterocyclic carbene has been successfully used in a Pd(0)-catalyzed allylic substitution for the first time. It was found that allylic substitution with a soft nucleophile using a Pd-carbene catalyst proceeds via retention of configuration, the stereochemical reaction pathway being the same as that of the reaction using a Pd-phosphine complex.
N-Heterocyclic carbenes as ligands in palladium-catalyzed Tsuji-Trost allylic substitution
Sato, Yoshihiro,Yoshino, Taro,Mori, Miwako
, p. 5753 - 5758 (2007/10/03)
A Pd(0)-catalyzed allylic substitution (i.e., Tsuji-Trost reaction) using N-heterocyclic carbene as a ligand was investigated. It has been proven that an imidazolium salt 2d having bulky aromatic rings attached to the nitrogens in its imidazol-2-ylidene skeleton is suitable as a ligand precursor and that a Pd2dba3-imidazolium salt 2d-Cs2CO3 system is highly efficient for producing a Pd-NHC catalyst in this reaction. Allylic substitution using a Pd-NHC complex differed from that using a Pd-phosphine complex as follows: (1) the reaction using a Pd-NHC complex required elevated temperature (50 °C or reflux in THF), (2) allylic carbonates were inert to a Pd-NHC complex, and (3) nitrogen nucleophiles such as sulfonamide and amine did not react with allylic acetate. It was also found that allylic substitution with a soft nucleophile using a Pd-NHC catalyst proceeds via overall retention of configuration to give the product in a stereospecific manner, the stereochemical reaction course obviously being the same as that of the reaction using a Pd-phosphine complex.
