α,β-不饱和羰基化合物和叔/仲α-甲硅烷基胺的对映选择性光氧化还原反应是通过易于获得的单一Ni II –DBFOX催化剂实现的(DBFOX = 4,6-bis(( R )-4-苯基-4, 5-二氢恶唑-2-基)二苯并[ b , d ]呋喃)在可见光条件下。非贵重的手性催化剂参与光化学过程以引发单电子转移,同时为随后的自由基转变提供良好组织的手性环境。手性 γ-氨基羧酸衍生物和 γ-内酰胺的形成获得了良好至优异的对映选择性 (80–99% ee)。
Magnesium Complexes as Highly Effective Catalysts for Conjugate Cyanation of α,β-Unsaturated Amides and Ketones
作者:Jinlong Zhang、Xihong Liu、Rui Wang
DOI:10.1002/chem.201304835
日期:2014.4.22
Asymmetric cyanation of trimethylsilyl cyanide (TMSCN) with α,β‐unsaturated amides and ketones, respectively, catalyzed by bifunctional mononuclear 1,1′‐bi‐2‐naphthol (BINOL)–Mg and binuclear bis(prophenol)–Mg catalysts was realized. A series of synthetically important 1,4‐cyano products were obtained with good to high enantioselectivities (up to 97 % ee).
A highly enantioselective tandem Michael/ring‐closurereaction of α,β‐unsaturated pyrazoleamides and amidomalonates has been accomplished in the presence of a chiral N,N′‐dioxide–Yb(OTf)3 complex (Tf: trifluoromethanesulfonyl) to give various substituted chiral glutarimides with high yields and diastereo‐ and enantioselectivities. Moreover, this methodology could be used for gram‐scale manipulation
A highly efficient N,N′-dioxide/Gd(III) complex has been developed for the enantioselective conjugate addition of nitroalkanes to α,β-unsaturated pyrazolamides. Under mild reaction conditions, a series of γ-nitropyrazolamides were obtained in good to excellent yields (up to 99%) with excellent enantioselectivities (up to 99% ee). What’s more, the optically active products could be easily transformed
Organocatalytic asymmetric domino sulfa-Michael–aldol reactions of 2-mercaptobenzaldehyde with α,β-unsaturated N-acylpyrazoles for the construction of thiochromane
作者:Xiu-Qin Dong、Xin Fang、Hai-Yan Tao、Xiang Zhou、Chun-Jiang Wang
DOI:10.1039/c2cc31891a
日期:——
An efficient protocol for the direct construction of bioactive thiochromanes was developed via a catalytic asymmetric cascade sulfa-Michaelâaldol reaction of 2-mercaptobenzaldehyde with α,β-unsaturated N-acyl imides. The key to the present methodology is introducing a pyrazole moiety as H-bond acceptor, which allowed for better organization and activation and hence higher enantioselectivity.