Highly Diastereoselective Epimerization: Stereodivergent Synthesis of α-Hydroxy-β-amino Isopentanoic Acid
摘要:
The high diastereoselectivity of the base-catalyzed epimerization of oxazolidin-2- ones 7 and 8 is shown to depend on the nature of the N-substituent (R group); when R = Bn, the 4,5-trans-product (4S,5R)-9 is formed, whereas when R = H the 4,5-cis-product (4S,5S)-10 is formed, both with > 99:1 dr. The successful hydrolysis of the oxazolidin-2-one group in both cis- and trans-derivatives show this to be a stereodivergent route to enantiopure alpha-hydroxy-beta-amino isopentanoic acids (2R,3S)-1 and (2S,3S)-2.