Phosphoric Acid → HCID 22029338, compound

Participants

Reaction Steps

The compound 5-chloropentan-1-ol (16.2 mL) was dissolved in cold 5 mM 2,2,6,6-tetramethylpiperidine-1-yloxy (tempo) in dichloromethane (240 mL) and cooled down to 0° C. with an ice bath. Potassium bromide (0.5 M in water, 24 mL) was added, and this was followed by the addition (in one portion at 5° C. under vigorous stirring) of a solution of sodium hydrogencarbonate (24 g) in aqueous sodium hypochlorite (0.3 M, 500 mL). The resulting mixture was stirred at 5° C. for 20 min, and the phases were separated. The water phase was extracted with dichloromethane (200 mL), and the combined organic phases were evaporated in vacuo giving 5-chloropentanal as a clear oil (16 g). Subsequently, 5-chloropentanal was suspended in water (100 mL) followed by addition of 4-fluorophenylhydrazine hydrochloride (19.5 g) and toluene (800 mL), and the mixture was stirred at room temperature for 15 min. Phosphoric acid (85%, 100 mL) was added and the mixture was boiled under reflux for 2 h. The mixture was cooled to room temperature and the phases were separated. The organic phase was washed with saturated aqueous sodium hydrogencarbonate, dried (MgSO4) and evaporated in vacuo to yield an orange oil. The crude product was purified by flash chromatography on silicagel (eluent: ethylacetate/heptane 1:4) to give the title compound as an orange oil (14 g).

Provenance & Evidence