evidence suggest that the oxidative coupling reaction is turnover‐limited by the step of iminium formation, and it is this step that is promoted by the chloride anion. Since it is more efficient than and mechanistically distinct from the well‐studied simple copper salts such as CuBr and CuCl2, the binuclear copper catalyst provides a new tool for oxidative coupling reactions.
Catalytic Enantioselective Protonation of α-Oxygenated Ester Enolates Prepared through Phospha-Brook Rearrangement
作者:Masashi Hayashi、Shuichi Nakamura
DOI:10.1002/anie.201007568
日期:2011.3.1
chiral: The organocatalytic enantioselective reaction of α‐ketoesters with phosphites using cinchona alkaloids and Na2CO3 has afforded α‐phosphonyloxy esters with high enantioselectivities (see scheme). This process allows the formation of both enantiomers of the product. A catalyst loading of as low as 2 mol % does not result in a significant decrease of the enantioselectivity.
膦酸酯变为手性:使用金鸡纳生物碱和Na 2 CO 3,α-酮酸酯与亚磷酸酯的有机催化对映选择性反应提供了高对映选择性的α-膦酰氧基酯(参见方案)。该过程允许形成产物的两种对映异构体。低至2mol%的催化剂负载量不会导致对映选择性的显着降低。
Direct Enantioselective Three-Component Kabachnik-Fields Reaction Catalyzed by Chiral Bis(imidazoline)-Zinc(II) Catalysts
作者:Mutsuyo Ohara、Shuichi Nakamura、Norio Shibata
DOI:10.1002/adsc.201100482
日期:2011.12
A direct three-component reaction of aldehydes, amines and diaryl phosphites was catalyzed by a zinc(II) complex of 1,3-bis(imidazolin-2-ly)pyridine (pybim) giving the corresponding α-aminophosphonates in good yield with good enantioselectivity. The reaction was applied to a wide variety of aromatic aldehydes to give products with excellent yields (up to 99%) and enantiomeric excesses (up to 93% ee)