Chiral Phosphoric Acid-Catalyzed Asymmetric Synthesis of Axially Chiral Arylpyrazole.

A chiral phosphoric acid-catalyzed efficient, operationally simple, general method for straightforward syntheses of axially chiral arylpyrazole employing -alkyl of 3-aryl-5-aminopyrazoles reacting with azonaphthalenes was achieved. A wide variety of axially chiral heterobiaryl diamines in generally good yields with excellent enantioselectivities were obtained under mild conditions. In addition, a scaled-up experiment and postmodification of the chiral product further highlighted the synthetic utility.

Asymmetric Synthesis of Polycyclic Heterocyclic Compounds via Friedel-Crafts Reaction/Cyclization Reaction Catalyzed by Nickel Catalyst.

The first highly enantioselective asymmetric Friedel-Crafts reaction/cyclization reaction of 5-aminopyrazoles with 3-alkenyloxindoles to afford polycyclic heterocyclic compounds bearing an all-carbon quaternary stereocenter catalyzed by a complex of Ni with the -symmetric bipyridine-,'-dioxide ligand has been developed. The relevant products with a wide range of substrates and good functional tolerance were obtained in 89-98% yield with 56-99% ee in the presence of 10 mol % Ni(OTf) and 11 mol % in DCM at 25 °C. Moreover, an experiment on scaling up the process along with the transformations of the cycloadducts further emphasized the practical application of the synthesis.