Synthesis of substituted nitroolefins: a copper catalyzed nitrodecarboxylation of unsaturated carboxylic acids
作者:Balaji V. Rokade、Kandikere Ramaiah Prabhu
DOI:10.1039/c3ob41408f
日期:——
A novel, mild and convenient method for the nitrodecarboxylation of substituted cinnamic acid derivatives to their nitroolefins is achieved using a catalytic amount of CuCl (10 mol%) and tert-butyl nitrite (2 equiv.) as a nitrating agent in the presence of air. This reaction provides a useful method for the synthesis of β,β-disubstituted nitroolefin derivatives, which are generally difficult to access from other conventional methods. Additionally, this reaction is selective as the E-isomer of the acid derivatives furnishes the corresponding E-nitroolefins. One more salient feature of the method is, unlike other methods, no metal nitrates or HNO3 are employed for the transformation.
Building the buildingblocks: A highly enantioselective hydrogenation of β‐aryl‐β‐alkyl disubstituted nitroalkenes 1 has been developed. This method results in enantiomericallypure nitroalkanes 2, which are versatile precursors for chemical synthesis.
protocol was developed for the preparation of allylic sulfones through direct condensation of sodium arylsulfinates and β,β-disubstituted nitroalkenes. The key step of this process was the Lewis base-promoted equilibrium between nitroalkenes and allylic nitro compounds. Through this process, the readily available conjugated nitroalkenes can be easily converted into allylic nitro compounds, which contain
Water-Enabled Catalytic Asymmetric Michael Reactions of Unreactive Nitroalkenes: One-Pot Synthesis of Chiral GABA-Analogs with All-Carbon Quaternary Stereogenic Centers
作者:Jae Hun Sim、Choong Eui Song
DOI:10.1002/anie.201611466
日期:2017.2.6
new catalytic reactions for otherwise unreactive substrate systems. Under the “on water” reaction conditions, extremely unreactive β,β‐disubstituted nitroalkenes smoothly underwent enantioselective Michael addition reactions with dithiomalonates using a chiral squaramide catalyst, affording both enantiomers of highly enantioenriched Michael adducts with all‐carbon‐substituted quaternarycenters. The
A highly efficient, iridium-catalyzed, enantioselectivehydrogenation of β,β-disubstituted nitroalkenes has been developed. Using a complex consisting of iridium and (S,S)-f-spiroPhos as the catalyst, a variety of β,β-disubstituted nitroalkenes were successfully hydrogenated to the corresponding chiral nitroalkanes with excellent enantioselectivities (up to 98% ee) and high turnover numbers (TON=1000)