Dichloromethane → 1,1-Dimethylethyl N-[1-(2,5-difluorobenzoyl)-3-butyn-1-yl]carbamate

Participants

Reaction Conditions

Reaction Steps

An inerted vessel was charged dichloromethane (866 kg) and cooled to −20 to −10° C. Then iso-propylmagnesium chloride solution in THF (2M, 326.1 kg, 669 mol) was slowly added followed by 1-bromo-2,5-difluorobenzene (120.1 kg, 622 mol). After 2 h at this temperature, an additional charge of iso-propylmagnesium chloride in THF solution was slowly added (2M, 58.65 kg, 121 mol) and the reaction aged 1 h. Then, a drop-wise addition of a dichloromethane solution of tert-butyl (1-[methoxy(methyl)amino]-1-oxopent-4-yn-2-yl)carbamate (70.8 kg, 276 mol in 292 kg dichloromethane) was conducted over 2 h at −20 to −20° C. The mixture was then warmed to room temperature and stirred for 10 h. The reaction was then slowly reverse quenched into aqueous ammonium chloride (175.6 kg in 1550 kg of water) at 5-10° C. The solution pH was then adjusted to ˜7 by adding 68 kg of con. HCl. The layers were then separated and the aqueous extracted with dichloromethane (414 kg). The combined organics were then dried with Na2SO4, filtered, treated with activated carbon (10 kg), filtered, and concentrated to 71-141 L. A constant volume (71-141 L) vacuum distillation solvent switch to n-heptane was then performed to crystallize the product. The slurry was then cooled to 0° C. and stirred 2 h. The slurry was filtered and the cake washed with n-heptane, 2-propanol, and then water. The solids were dried under vacuum at 40-50° C. overnight to give tert-butyl [1-(2,5-difluorophenyl)-1-oxopent-4-yn-2-yl]carbamate.

Provenance & Evidence