An operationally trivial and environmentally benign procedure for direct Michaeladdition has been developed. The reaction of various ketones with nitroolefins can be performed in water to afford the corresponding nitro compounds in high yields in the presence of a pyrrolidine–thiourea organocatalyst at 35 °C. The reaction exhibits a high stereoselectivity, with high enantioselectivities (up to 99%)
An Effective Bifunctional Thiourea Catalyst for Highly Enantio- and Diastereoselective Michael Addition of Cyclohexanone to Nitroolefins
作者:Wen-Jing Xiao、Yi-Ju Cao、Hai-Hua Lu、Yuan-Yuan Lai、Liang-Qiu Lu
DOI:10.1055/s-2006-950339
日期:2006.11
A series of new tunable and bifunctional thiourea catalysts have been synthesized and their catalytic activities are evaluated in the direct Michaeladdition of cyclohexanone to nitroolefins. High isolated yields (up to 97%), enantioselectivities (up to 98%) and diastereoselectivities (up to 99:1) were obtained under the optimal conditions.
Stereoselective Three‐Step One‐Pot Cascade Combining Amino‐ and Biocatalysis to Access Chiral γ‐Nitro Alcohols**
作者:Christian Ascaso‐Alegre、Raquel P. Herrera、Juan Mangas‐Sánchez
DOI:10.1002/anie.202209159
日期:2022.10.4
Chemoenzymatic cascades offer a simple and efficient way to rapidly build structural complexity. A three-step one-pot process is reported in which a Wittigreaction, chiral-thiourea-mediated asymmetric conjugate addition, and a bioreduction step were combined to access chiral nitro alcohols from commercially available benzaldehyde derivatives in good overall yields and excellent diastereomeric and