Synthesis of Axially Chiral Biaryls through Cobalt(II)-Catalyzed Atroposelective C-H Arylation.

Highly efficient synthesis of axially chiral biaryl amines through cobalt-catalyzed atroposelective C-H arylation using easily accessible cobalt(II) salt and salicyloxazoline ligand has been reported. This methodology provides a straightforward and sustainable access to a broad range of enantioenriched biaryl-2-amines in good yields (up to 99 %) with excellent enantioselectivities (up to 99 % ee). The synthetic utility of the unprecedented method is highlighted by its scalability and diverse transformations.

Brønsted Acid-Catalyzed Formal (3+3)-Annulation of Propargylic (Aza)-para-Quinone Methides with 4-Hydroxycoumarins and 1,3-Dicarbonyl Compounds.

Herein, we describe a highly effective 1,8-conjugate-addition-mediated formal (3+3)-annulation of (aza)-para-quinone methides in situ generated from propargylic alcohols with 4-hydroxycoumarins and 1,3-dicarbonyl compounds under the catalysis of a Brønsted acid. This methodology affords efficient and practical access to synthetically important and highly functionalized pyranocoumarins and pyrans in excellent yields under mild conditions. Importantly, these products exhibit impressive inhibitory activity toward α-glucosidase.

Copper-catalyzed monoselective C-H amination of ferrocenes with alkylamines.

A copper-catalyzed mono-selective C-H amination of ferrocenes assisted by 8-aminoquinoline is presented here. A range of amines, including bioactive molecules, were successfully installed to the ortho-position of ferrocene amides with high efficiency under mild conditions. A range of functionalized ferrocenes were compatible to give the aminated products in moderate to good yields. The gram-scale reaction was smoothly conducted and the directing group could be removed easily under basic conditions.

Pd(II)-Catalyzed Atroposelective C-H Allylation: Synthesis of Enantioenriched N-Aryl Peptoid Atropisomers.

A Pd-catalyzed atroposelective C-H allylation with 1,1-disubstituted alkenes was developed for the synthesis of enantioenriched N-aryl peptoid atropisomers via ß-H elimination using commercially available and inexpensive L-pGlu-OH as a chiral ligand. Exclusive allylic selectivity was achieved. Additionally, a series of enantioenriched N-aryl peptoid atropisomers were obtained in synthetically useful yields with excellent enantioselectivities (up to 90% yield and 97% ee).

Palladium-Catalyzed Directed Atroposelective C-H Allylation via ß-H Elimination: 1,1-Disubstituted Alkenes as Allyl Surrogates.

Transition-metal-catalyzed dehydrogenative C-H allylation with 1,1-disubstituted alkenes via ß-H elimination remains challenging, because of the low reactivity and difficulty of controlling selectivity. Herein, the development of a Pd(II)-catalyzed directed atroposelective C-H allylation with methacrylates is described. Exclusive allylic selectivity was achieved. A vast array of axially chiral biaryl-2-amines are efficiently synthesized with excellent enantioselectivities (up to >99% enantiomeric excess).