Possible Case of Halogen Bond-Driven Self-Disproportionation of Enantiomers (SDE) via Achiral Chromatography.

The major breakthrough reported in this work is the discovery of likely halogen bond-driven self-disproportionation of enantiomers (SDE). Taking into account that the halogen-bonding interactions can be rationally designed and can match, or even exceed, the strength of the more familiar hydrogen bond, this discovery clearly opens an unexpected new direction of research in the areas of molecular chirality and the SDE phenomenon.

Catalytic Enantioselective Synthesis of N-C Axially Chiral Mebroqualone and Its Derivatives through Reductive Asymmetric Desymmetrization.

In the presence of (R)-DTBM-SEGPHOS-Pd(OAc)2 catalyst, treatment of various 3-(2,6-dibromophenyl)quinazolin-4-ones with NaBH4 gave optically active N-C axially chiral quinazolinone (mebroqualone) derivatives through reductive asymmetric desymmetrization (enantioselective monohydrodebromination) followed by kinetic resolution of the resulting monobromophenyl products (up to 99% ee). The enantioselectivity strongly depended on the substituent (R2) at the C4'position, amount of NaBH4, and reaction temperature.