Catalyzed by a Rh/bisphosphine–thiourea (L1) complex, isoquinolines and quinolines are hydrogenated with high conversions and high enantioselectivities.
Asymmetric hydrogenation of unprotected N-H imines catalyzed by Rh/bisphosphine-thiourea provided chiral amines with up to 97% yield and 95% ee. 1H NMR studies, coupled with control experiments, implied that catalytic chloride-bound intermediates were involved in the mechanism via the dual hydrogen-bonding interaction. Deuteration experiments proved that the hydrogenation proceeded through a pathway consistent with the imine.
Copper-catalyzed cross-coupling of N-tosylhydrazones with N-iminopyridinium ylides leads to the direct C-H alkylation. This direct C-H bond alkylation transformation uses inexpensive CuI as the catalyst without any ligand. The reaction is operationally simple and conducted under mild conditions, giving the corresponding alkylated pyridines in moderate to good yields. DFT calculation provides insights into the reaction mechanism, suggesting that the reaction proceeds through the Cu carbene migratory insertion process.
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