Scalable syntheses of (2 S,3 S)-3- N- tert-butoxycarbonylamino-2-hydroxy-4-phenylbutanoic acid (BocAHPBA) 1 and ( R)-3- tert-butoxycarbonyl-5,5-dimethyl-1,3-thiazolidine-4-carboxylic acid (BocDMTA) 2 have been developed. Both 1 and 2 can serve as chiral building blocks in assembling JE-2147 (KNI-764) 3, a potent HIV protease inhibitor. The synthesis of (2 S,3 S)-BocAHPBA 1 is achieved in 41% overall yield from ( S)-2- N, N-dibenzylamino-3-phenylpropanal 4 in five steps where Tamao's reagent [Me 2( i-PrO)SiCH 2MgCl] is employed for a one-carbon homologation, and Zhao's oxidation protocol (TEMPO, NaClO 2, NaClO) is applied to convert a 1,2-glycol moiety into an α-hydroxy acid motif. ( R)-BocDMTA 2 is synthesized with 99.4% ee in 24% yield via enantioselective hydrolysis of methyl (±)-5,5-dimethyl-1,3-thiazolidine-4-carboxylate 8b by a Klebsiella oxytoca hydrolase; the unreacted ( S)-ester 8b can be recovered and racemized with NaOMe to afford (±)- 8b in 46% yield for another round of the enzymatic processing.