Hydrochloric Acid → 6-Chloro-3-iodo-2-(trifluoromethyl)pyridine

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a stirred solution of 7.1 ml of n-BuLi (1.6M in hexane, 11.3 mmol) in 7 ml THF under argon at −73° C. were added 1.6 ml of diisopropylamine (11.3 mmol) in 3 ml THF within 8 min. After 10 min stirring at the same temperature a solution of 1 g of 2-chloro-6-(trifluoromethyl)-pyridine (5.51 mmol) in 5 ml THF was added within 15 min (temperature between −76 and −75° C.). The dark brown solution was stirred at −75° C. for 1 h 15 min. Finally a solution of 1.4 g of iodine (5.51 mmol) in 10 ml THF was added at −75° C. over 25 min. After additional 45 min stirring at the same temperature 12 ml 2M aqueous HCl were added within 2 min (temperature raised from −78 to −50° C. The cooling device was then removed, the reaction mixture diluted with diethylether. After separation of the organic phase, the aqueous phase was reextracted with diethylether. The combined organic phases were successively washed with 10 ml 1M sodium thiosulfate, saturated NaHCO3 and brine, dried over magnesium sulfate, filtered off and concentrated in vacuo to yield 1.54 (69%) of 6-chloro-3-iodo-2-trifluoromethyl-pyridine as a brown semisolid residue. MS: 307.0

Herkunft & Nachweise