Resolving (N)-carbethoxy-alpha-amino-phenylacetic acid - by seeding supersaturated soln. with required enantiomer to give penicillin intermediates

摘要

Prodn. of optically active N-carbethoxy-alpha-aminophenylacetic acid (I) comprises first preparing a supersatd. soln. of racemic (I) in an inert solvent, then seeding with crystals of the enantiomer required. The crystals formed are recovered then more racemate added to the residual soln. to saturate it again. This new soln. is then seeded with crystals of the other enantiomer and a second crop of crystals collected. The process is repeated until all the racemate has been resolved. D(-) (I) is an intermediates, pref. by hydrolysis with HBr, for D(-)-alpha-aminophenylacetic acid an intermediates for semi-synthetic penicillins. (I) is inexpensive, readily available and can be resolved more simply than other alpha-aminophenylacetic acid derivs. without the need for an optically active resolving agent.