1-Chloro-3-iodopropane → 4-Bromo-5-(3-chloro-propyl)-3-methyl-pyrazole-1-sulfonic acid dimethylamide

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-bromo-3-methyl-pyrazole-1-sulfonic acid dimethylamide (6.7 g, 25 mmol) in diethyl ether (75 mL) was added dropwise at −78° C. under N2 phenyl lithium (1.8 M, 14.6 mL, 26.3 mmol) in dibutyl ether. After warming to 0° C. for 15 m, the reaction mixture was re-cooled to −78° C. and a solution of 3-chloro-iodopropane (15.3 g, 75 mmol) in 20 mL THF was added dropwise. The reaction was warmed to room temperature and stirred for 3 h before quenching with a saturated aqueous solution of NH4Cl. The quenched reaction mixture was extracted with EtOAc and the organic layer was dried over Na2SO4, filtered and concentrated. The crude product was purified over normal phase silica starting with 5% EtOAc in heptane for 10 m and then increasing to 50% EtOAc in heptane for 20 m to give the desired product as a clear oil (3.85 g, 11.2 mmol) MS m/z 346.3 (M+H)+.

Provenance & Evidence