Asymmetric Transfer Hydrogenation of 3‐Nitroquinolines: Facile Access to Cyclic Nitro Compounds with Two Contiguous Stereocenters

Abstract

Hi, neighbor! The first organocatalyzed asymmetric transfer hydrogenation of aromatic nitro compounds was successfully developed with up to 99 % ee. The new methodology provides a direct and facile access to enantiopure cyclic nitro compounds with two contiguous stereocenters.

Synthesis of Fluorinated Heteroaromatics through Formal Substitution of a Nitro Group by Fluorine under Transition‐Metal‐Free Conditions

“…In organic synthesis, the nitro group is viewed as a synthetically important functional group owing to its easy availability and transformation into a variety of diverse functionalities 7. 8 Very recently, as part of our ongoing efforts to promote the development of asymmetric hydrogenations of heteroaromatic compounds,9, 10 3‐nitroquinolines have been studied (Scheme a) 11. Due to the high electron‐withdrawing and conjugative effect of the nitro group, the 1,4‐reduction intermediate 3 was relatively stable in the asymmetric transfer hydrogenation (ATH) process; thus, it was isolated and used in further transformations to give more insights on the mechanism.…”

“…[7,8] Very recently, as part of our ongoing efforts to promote the development of asymmetric hydrogenations of heteroaromatic compounds, [9,10] 3-nitroquinolines have been studied (Scheme 2 a). [11] Due to the high electron-withdrawing and conjugative effect of the nitro group, the 1,4-reduction intermediate 3 was relatively stable in the asymmetric transfer hydrogenation (ATH) process; thus, it was isolated and used in further transformations to give more insights on the mechanism. The key-intermediate enamine 3 [12] also inspired us to investigate the possibility of combining the partial reduction process with other transformations.…”

Catalytic Asymmetric Transfer Hydrogenation of Imines: Recent Advances

“…The ATH has also been applied to functionalized quinolines in order to diastereo‐ and enantioselectively prepare tetrahydroquinolines. Thus, this methodology was used for quinolines bearing sulfonamido, trifluoromethyl, nitro, or fluoro substituents mainly at the 3‐position, working with a Hantzsch ester 79 and a phosphoric acid 78 with different substitution at the 3‐ and 3′‐positions. In general, yields, diastereo‐ and enantioselectivities were high.…”

Catalytic, Enantioselective, Intramolecular Sulfenoamination of Alkenes with Anilines

“…Indeed, many enantioselective hydrogenation methods have been developed for the synthesis of syn -2,3-substituted tetrahydroquinolines. 3 Of course, the preparation of the starting quinolines then becomes the challenge. 1b …”