Umpolung α-regioselective 1,3-dipolar cycloaddition and internal recycle of byproduct as two key strategies: access to diverse chiral bipyridines

Abstract

Herein, the first example of umpolung α-regioselective 1,3-dipolar cycloaddition of optically pure perhydroindole-2-carboxylic acid 1a with pyridinecarboxaldehydes 2 is described.

Design of rigid chiral bipyridine-2NO tetradentate ligands: application in asymmetric catalysis

“…Based on the above experimental data and work of Xie, 15 Feng 11 and our previous group, 12 a plausible catalytic mode for this Friedel–Crafts alkylation reaction is presented (Scheme 8). L1a as a tetradentate ligand coordinated to Ni( ii ) via two oxygen and two nitrogen atoms.…”

Phen-2NO, a new C2-symmetric rigid-featured tetradentate ligand, and its application in the asymmetric alkylation reaction of indoles

“…The chiral Phen-2NO ligand L1a can be smoothly obtained in 42% overall yield with >20 : 1 dr via condensation of l -prolinamide 1a and phenanthroline-dicarbaldehyde 2 and subsequent regioselective N -oxidation 8,9 with m -CPBA as the oxidant in two steps.…”