Enantioselective Synthesis of 4-Aminotetrahydroquinolines via 1,2-Reductive Dearomatization of Quinolines and Copper(I) Hydride-Catalyzed Asymmetric Hydroamination

Abstract

A 1,2-reductive dearomatization of quinolines and copper­(II) acetate monohydrate/(R,R)-Ph-BPE/P­(p-tolyl)3-catalyzed enantioselective hydroamination sequence was developed, affording diverse 4-amino-1,2,3,4-tetrahydroquinolines with high levels of enantioselectivity in either a stepwise or one-pot fashion. Pleasingly, internal cis-cyclic alkenes, which are challenging substrates in copper hydride-catalyzed enantioselective hydroamination reactions, were transformed efficiently under mild conditions.

Synthesis of 1,2-Dihydroquinolines via Hydrazine-Catalyzed Ring-Closing Carbonyl-Olefin Metathesis

“…So the NMR yield of 1 is around 7%. The spectral data for compound 54 matched that of the reported compound 11.…”

Asymmetric hydroamination with far fewer chiral species than copper centers achieved by tuning the structure of supramolecular helical catalysts

“…The asymmetric Cu–H promoted hydroamination of alkenes 55–57 is performed efficiently by a relatively narrow number of chiral diphosphine ligands, 58–83 with particularly strong effects exerted by substituents located on the aryl rings attached to the phosphorus atom. 84,85 In addition to BTA ligands, BTA P H and BTA P Me , previously investigated in the copper-catalysed hydrosilylation of acetophenone derivatives, 51,52,54 it appears desirable to investigate more electron poor ligands as it may facilitate the hydrocupration step of the catalytic cycle.…”

Synthesis of Cyclic Amidines from Quinolines by a Borane-Catalyzed Dearomatization Strategy

“…This could be an attractive approach to reach the endocyclic enamines. However, the isolation of the cyclic enamines has been impeded by its intrinsic instability. , To circumvent it, in situ utilization of the cyclic enamine intermediate has been used . Recently, a dearomative hydrosilylation of N -heteroarenes was achieved by Chang and Park by using a borane catalyst [B­(C 6 F 5 ) 3 , 5 ] (Scheme b).…”