Preparation of Enantiomerically Pure Protected 4-Oxo-α-amino Acids and 3-Aryl-α-amino Acids from Serine

Article abstract of DOI:10.1021/jo00038a030

The organozinc reagent 13, prepared from the protected β-iodo alanine derivative 3c using ultrasonic activation, is efficiently acylated using acid chlorides in the presence of bis(triphenylphosphine)palladium dichloride to give enantiomerically pure protected 4-oxo-α-amino acids 17 in 39-90percent yield (13 examples).Zinc reagent 13 can also be coupled with aryl iodides in the presence of bis(tri-o-tolylphosphine)palladium dichloride to give enantiomerically pure protected phenylalanine analogues 26, 29, and 30 in 10-67percent yield (11 examples).The reaction tolerates the presence of a variety of functional groups in the acid chloride and the aryl iodide and provides derivatives which can be easily deprotected, at either the carboxyl or amino terminus, to give intermediates suitable for peptide synthesis.