Enantioselective Construction of C4-Quaternary Quinolinones via Copper(II)-Catalyzed Asymmetric [1,3] O-to-C Rearrangement.

An efficient asymmetric [1,3] O-to-C rearrangement of quinolin-2(1H)-ones enabled by a chiral bisoxazoline/copper complex has been developed. This strategy tolerated a wide range of substrates to provide a series of 1,4-dihydroquinoline-2,3-diones containing a quaternary stereocenter. A further cyclization of the [1,3] O-to-C rearrangement products was also realized, which led to various optically active 3,4-dihydroquinolin-2-ones with broad substrate scope.

Access to Chiral Chromenones through Organocatalyzed Mannich/Annulation Sequence.

Herein we report an efficient and practical method to access chiral chromenones bearing one α-amino stereogenic center in the ß position of the carbonyl group. The quinine-derived squaramide could efficiently promote Mannich/cycloketalization/dehydration tandem reactions between 1-(2-hydroxyaryl)-1,3-diketones and functionalized imines generated in situ, providing a wide range of chiral chromenones with propargylamine or α-amino ester moieties with good results (54 examples, up to 98% ee).

Palladium-Catalyzed Selective [2 + 2 + 2] Annulation of 2-(2-Enynyl)pyridines with Arynes.

The palladium-catalyzed chemo- and stereoselective [2 + 2 + 2] annulation reaction of 2-(2-enynyl)pyridines with arynes has been developed. A wide range of (E)- or (E/Z)-isomers of 2-(2-enynyl)pyridines and arynes was tolerated, providing a spectrum of (E)-phenanthrenylated 2-alkenylpyridines in good yield, together with the generation of a chiral axis between an alkene and a phenanthrene ring.

Correction: Assembly of fluorinated chromanones via enantioselective tandem reaction.

Correction for 'Assembly of fluorinated chromanones via enantioselective tandem reaction' by Mengxue Lu et al., Chem. Commun., 2021, 57, 4722-4725, DOI: 10.1039/D1CC01187A.

Assembly of fluorinated chromanones via enantioselective tandem reaction.

The enantioselective synthesis of fluorinated tricyclic chromanones with multiple vicinal stereogenic centers has been realized for the first time, through the tandem reaction between 2-fluorinated 1-(2-hydroxyaryl)-1,3-diketones and α,ß-unsaturated aldehydes. In the presence of chiral amine, the organo-tandem reaction including catalytic Michael addition/cycloketalization/hemiacetalization and acylation sequence provided a wide range of fluorinated tricyclic chromanones with excellent outcomes (>30 examples, up to >99% ee and >19 : 1 d.r.). A plausible catalytic cycle and transition state are also provided for this tandem reaction to rationalize the observed sense of asymmetric induction.