Concise and diastereoselective approach to syn- and anti-N-tosyl-α-hydroxy β-amino acid derivatives

Abstract The methyl diazoacetate and aryl ( N -tosyl)imines can be transformed into syn or anti α-hydroxy β-amino esters with high diastereoselectivities in three steps: the base promoted nucleophilic condensation of the methyl diazoacetate and aryl ( N -tosyl)imines to give β-( N -tosyl)amino α-diazoesters, followed by oxidation with Oxone ® to generate α-oxo esters, which were reduced with NaBH 4 to yield the anti - N -tosyl-α-hydroxy β-amino ester, or hydrogenated with Pd/C (10%) as the catalyst to yield corresponding syn isomer, both in high diastereoselectivity.