A generalprotocol to independently access stereoisomerically pure β′-hydroxy-β-amino acid derivatives that is based on dibutylboron triflate-mediated aldol reaction of suitably protected β-amino acids bearing chiral oxazolidinone auxiliary is reported. The method smoothly afforded syn-aldol (α,β′-syn) products in pure form and excellent isolated yield. Both α,β-syn and α,β-anti isomers are readily