Few (Z)-alpha-N-benzoylamino-beta-(fluorophenyl)-acrylic acids and their esters were prepared by known procedures and hydrogenated to the corresponding optically active alpha-benzoyl-beta-(fluorophenyl)-alanine derivatives with optical yields up to 90% using the rhodium complexes of "PROPRAPHOS" and O,N-bis(diphenylphosphino)-2-exo-hydroxy, 3-endo-methylamino-norbornane as chiral catalysts. The method proved to be apt for upscaling the preparation. Deacylation of the obtained amino acids gave the hydrochlorides of the fluorinated phenylalanines in very pure state.
Rh(<scp>iii</scp>)-Catalyzed diastereoselective transfer hydrogenation: an efficient entry to key intermediates of HIV protease inhibitors
A highlyefficient diastereoselective transferhydrogenation of α-aminoalkyl α'-chloromethyl ketones catalyzed by a tethered rhodium complex was developed and successfully utilized in the synthesis of the key intermediates of HIV protease inhibitors. With the current Rh(iii) catalyst system, a series of chiral 3-amino-1-chloro-2-hydroxy-4-phenylbutanes were produced in excellent yields and diastereoselectivities