A Highly<i>anti</i>-Selective Asymmetric Henry Reaction Catalyzed by a Chiral Copper Complex: Applications to the Syntheses of (+)-Spisulosine and a Pyrroloisoquinoline Derivative
作者:Kun Xu、Guoyin Lai、Zhenggen Zha、Susu Pan、Huanwen Chen、Zhiyong Wang
DOI:10.1002/chem.201201775
日期:2012.9.24
A highly anti‐selective asymmetricHenryreaction has been developed, affording synthetically versatile β‐nitroalcohols in a predominately anti‐selective manner (mostly above 15:1) and excellent ee values (mostly above 95 %). Moreover, the anti‐selective Henryreaction was carried out in the presence of water for the first time with up to 99 % ee. The catalytic mechanism was proposed based on the detection
catalytic asymmetric Henry reaction has been developed with use of a sulfonyldiamine−CuCl complex as a catalyst. A series of new binaphthyl-containing sulfonyldiamine ligands (2a−h) were readily synthesized in two steps starting from commercially available chiral 1,2-diamines. The (R,R)-diamine-(R)-binaphthyl ligand (2d)−CuCl complex smoothly catalyzed the enantioselective Henry reaction with the assistance
Chromate Oxidation of α-Nitro Alcohols to α-Nitro Ketones: Significant Improvements to a Classic Method
作者:Tarek Elmaaty、Lyle Castle
DOI:10.3390/10121458
日期:——
A series of eight alkyl and aryl α-nitroketones were prepared by the potassium dichromate oxidation of the corresponding nitro alcohols. Short reaction times allowed for the easy isolation of pure nitro ketones that are devoid of starting materials and/or other oxidation side products.
A Highly syn-Selective Nitroaldol Reaction Catalyzed by CuII-Bisimidazoline
作者:Liang Cheng、Jiaxing Dong、Jingsong You、Ge Gao、Jingbo Lan
DOI:10.1002/chem.201000650
日期:——
Catalyzing Henry: Chiral bisimidazoline 1–Cu(OTf)2, in the presence of N‐methylmorpholine as a base, was discovered to efficiently catalyze the nitroaldolreaction in a highly syn‐ and enantioselective manner for a broad range of aldehydes, including aromatic, heteroaromatic, α,β‐unsaturated, and aliphatic aldehydes (see scheme).
diastereoselective Henry reaction of various aldehydes with nitroethane was developed using the guanidine-thioureabifunctional catalyst 1 (syn selectivity of 86:14 to 99:1 with 84–99 % ee). A variety of nitroalkanes was treated with unbranched and branched aldehydes and gave nitro alcohols with high syn diastereoselectivities (90:10 to 99:1) and high enantioselectivities (85–95 % ee). This reaction was successfully