Asymmetric Organocatalytic Tandem Cyclization/Transfer Hydrogenation: A Synthetic Strategy for Enantioenriched Nitrogen Heterocycles
作者:Feng Shi、Wei Tan、Hong‐Hao Zhang、Mei Li、Qin Ye、Guan‐Hua Ma、Shu‐Jiang Tu、Guigen Li
DOI:10.1002/adsc.201300576
日期:2013.12.16
AbstractAn asymmetric organocatalytic tandem reaction comprising cyclization/transfer hydrogenation has been established in a compatible and synergistic way, leading to the step‐economical synthesis of enantioenriched tetrahydroquinoxalines and dihydroquinoxalinones from readily accessible materials in excellent enantioselectivity of up to >99% ee. This protocol of a one‐operation tandem reaction combines the merits of both tandem reactions and asymmetric organocatalysis, providing an efficient strategy for concisely and enantioselectively synthesizing nitrogen heterocycles with biological relevance.magnified image
The First General, Efficient and Highly Enantioselective Reduction of Quinoxalines and Quinoxalinones
作者:Magnus Rueping、Francisco Tato、Fenja. R. Schoepke
DOI:10.1002/chem.200902907
日期:——
Simple yet efficient: A series of diverse substituted tetrahydroquinoxalines and dihydroquinoxalinones have been synthesized for the first time in a highly enantioselective fashion (see scheme). Using this metal‐free hydrogenation it is possible to isolate these products, which are of high pharmaceutical interest, in good yields and with excellent enantioselectivities in a minimal number of reaction