Hydrochloric Acid → HCID 14305409, compound

Participants

Reaction Steps

To a stirred solution of 396 mL (0.740 mol) of 1.9 molar lithium diisopropylamide (in hexanes) in 1.5 L dry tetrahydrofuran cooled to -70° under nitrogen was added dropwise a solution of 65 g (0.670 mol) of 2-fluoropyridine in 150 mL dry tetrahydrofuran such that the temperature was maintained below -65°. The suspension was stirred at -70° for another 3.5 hours and 86 g (1.34 mol) of sulfur dioxide was added while maintaining the temperature below -65°. After stirring another 15 minutes at -70°, the reaction was allowed to warm to 0° and evaporated to half the original volume and diluted with ether. The white precipitate was collected under nitrogen, washed with ether, and dried. The solid was dissolved in 800 mL acetic acid and cooled to 10°-20°. To this stirred solution was added portionwise 99.4 g (0.740 mol) of N-chlorosuccinimide while maintaining the temperature below 20°. After stirring another 30 minutes, the suspension was evaporated, diluted with water and extracted with methylene chloride. The combined organic phases were washed with saturated aqueous sodium bicarbonate solution until no more gas evolution, washed with brine, dried over magnesium sulfate, and filtered. The filtrate was cooled to -70° under nitrogen and to this stirred solution was added dropwise 199 g (2.7 mol) of t-butylamine. The suspension was poured into ice water, acidified with concentrated hydrochloric acid, and extracted with methylene chloride. The combined organic layers were washed with brine, dried over magnesium sulfate, and evaporated to an oil which was purified by flash chromatography to afford 29.1 g (19%) of a brown solid which was further washed with cold n-butylchloride to afford 22.4 g (14.5%) of a white solid: m.p. 95°-97°; NMR (CDCl3, 200 MHz) 1.25 (9H, s), 4.9 (NH), 7.35 (1H, m), 8.3-8.5 (2H, m).

Provenance & Evidence