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Ligand-accelerated enantioselective methylene C(sp3)-H bond activation.

ABSTRACT: Effective differentiation of prochiral carbon-hydrogen (C-H) bonds on a single methylene carbon via asymmetric metal insertion remains a challenge. Here, we report the discovery of chiral acetyl-protected aminoethyl quinoline ligands that enable asymmetric palladium insertion into prochiral C-H bonds on a single methylene carbon center. We apply these palladium complexes to catalytic enantioselective functionalization of ?-methylene C-H bonds in aliphatic amides. Using bidentate ligands to accelerate C-H activation of otherwise unreactive monodentate substrates is crucial for outcompeting the background reaction driven by substrate-directed cyclopalladation, thereby avoiding erosion of enantioselectivity. The potential of ligand acceleration in C-H activation is also demonstrated by enantioselective ?-C-H arylation of simple carboxylic acids without installing directing groups.

SUBMITTER: Chen G

PROVIDER: S-EPMC5516954 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature

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Ligand-accelerated enantioselective methylene C(sp3)-H bond activation.

Chen Gang G Gong Wei W Zhuang Zhe Z Andrä Michal S MS Chen Yan-Qiao YQ Hong Xin X Yang Yun-Fang YF Liu Tao T Houk K N KN Yu Jin-Quan JQ

Science (New York, N.Y.) 20160901 6303

Effective differentiation of prochiral carbon-hydrogen (C-H) bonds on a single methylene carbon via asymmetric metal insertion remains a challenge. Here, we report the discovery of chiral acetyl-protected aminoethyl quinoline ligands that enable asymmetric palladium insertion into prochiral C-H bonds on a single methylene carbon center. We apply these palladium complexes to catalytic enantioselective functionalization of β-methylene C-H bonds in aliphatic amides. Using bidentate ligands to accel ...[more]

PMID: 27701111

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