Tri-o-tolylphosphine → (S)-methyl 2-((tert-butoxycarbonyl)amino)-3-(4-cyano-2,6-dimethylphenyl)propanoate

Participants

Reaction Conditions

Reaction Steps

A 5 L three-necked round-bottomed flask equipped with a nitrogen inlet, a mechanical stirred, an addition funnel and a thermocouple was charged with 4-bromo-3,5-dimethyl-benzonitrile (210 g, 1.0 mol) and DMAc (750 ml). The resulting suspension was stirred and heated to 35° C. to dissolve the solids. To the resulting mixture was then added P(o-tol)3 (6.0 g, 0.02 mol), Pd2(dba)3 (9.2 g, 0.01 mol) and the resulting mixture heated to about 75-80° C. The cooled mixture prepared in STEP A above was added by cannula to the reaction mixture at a rate which maintained the temperature at about 75-80° C. (about 2 hours). The resulting suspension was cooled to ambient temperature, then aged overnight with moderate agitation. The resulting suspension was then heated to about 35-40° C., filtered with silica (540 g). The silica bed was washed with DMAc (400 mL×2), the combined DMAc solutions cooled to about 0-5° C. and then added slowly to a mixture of ice and deionized water. The resulting mixture was maintained cold for 2 hours, over which time a white solid was observed to precipitate. The resulting mixture was then warmed to ambient temperature and aged overnight. The solid precipitate was cooled by vacuum filtration using a Buchner funnel. The filter cake was rinsed with deionized water (1 L×3), air dried overnight, then dried in a vacuum oven overnight. MeOH (1 L) was added to the solid and the resulting slurry was cooled to about 0-5° C., then aged at this temperature for 1 hour, with stirring. The solid was collected by filtration, washed with cold methanol (400 mL) and dried in a vacuum oven at 45° C. to yield the title compound as an off-white solid.

Provenance & Evidence