Palladium-Catalyzed Asymmetric Hydrophosphination of Internal Alkynes: Highly Regio- and Stereoselective Construction of Axially Chiral Phosphines

Palladium-catalyzed unprecedented atroposelective hydrophosphination of internal alkynes has been realized using diarylphosphines, affording C-N axially chiral trisubstituted olefins (vinylphosphines) in excellent regioselectiviry, (E)-selectivity, and enantioselectivity. The axial chirality was established via integration of hydrophosphination and dynamic kinetic transformation of the alkynes, with both symmetrical and nonsymmetrical secondary phosphines being applicable. In the latter case, additional P-central chirality has been constructed in good diastereoselectivity.

The Efficient Synthesis of 2-(3-Carbamoylpyridine-2-yl) nicotinamide Pyridine Salts

: The synthesis of axially chiral compounds has attracted a great deal of attention in the recent years. Herein, an efficient and economical synthetic route has been developed for 2-(3-carbamoylpyridin-2-yl) nicotinamide pyridine salts, an axially chiral compound. The starting material 1,10-phenanthroline has been readily available and 2-(3-carbamoylpyridin-2-yl) nicotinamide pyridine salts have been obtained in moderate to good yields. This protocol features simple operation and easy scalability. In addition, the axial chirality of the products has also been preliminary studied.

New dibenzocyclooctadiene lignan from Schisandra chinensis (Turcz.) Baill. fruits

Repeated column chromatography using Sephadex LH-20, silica gel (SiO2), and octadecyl SiO2 (ODS) as well as preparative HPLC column chromatography led to isolation of a new dibenzocyclooctadiene lignan along with four known ones, gomisin L2 (1), L1 (2), M1 (3), and M2 (4). Their chemical structures were fixed based on MS, IR, and NMR data analyses. In addition, the stereochemistry of atropisomers, the absolute configuration of the axial chirality in a biphenyl structure, was confirmed by a CD experiment. The new lignan was named gomisin M3 (5).