Chromium(III) chloride

Chromium(III) Chloride-Catalyzed Regioselective Hydropyridylation of Styrene

Li, Yuexuan, et al. Organometallics, 2016, 35, 5, 747-750.

Low-cost chromium(III) chloride combined with cyclohexyl Grignard reagent and 2,2'-bipyridine promotes hydrogen functionalization reaction, which can form branched products with high selectivity by cleaving the inert C-H bond of pyridine.
Procedure for Chromium-Catalyzed Hydropyridination of Styrenes
· In a dried Schlenk flask were placed CrCl3 (8 mg, 0.05 mmol), 2,2'-bipyridine (16 mg, 0.1 mmol), pyridine (40 μL, 0.5 mmol), and DBU (112 μL, 0.75 mmol).
· Then, a solution of cyclohexylmagnesium bromide in THF (0.5 mmol, 0.5 mL) was added dropwise at 0 °C.
· After stirring for 30 min, styrene (75 μL, 0.65 mmol) was added, and the reaction mixture was stirred at 80 °C for 48 h.
· Subsequently, the mixture was cooled to room temperature and quenched with a solution of NH4Cl.
· The crude product was extracted with ethyl acetate and dried with anhydrous Na2SO4.
· After removing the volatiles under vacuum, the residue was purified by flash silica gel column chromatography (eluent: petroleum/EtOAc/Et3N = 25/5/1) to give the adduct compound.