(2R*,3S*)-2-(tert-butoxy-carbonylamino)-3-hydroxy-4-methyl-pentanoate → (2R,3S)-2-amino-3-hydroxy-4-methylpentanoic acid

Participants

Reaction Conditions

Reaction Steps

In a 35 ml microwave vial, the diastereomeric mixture containing ethyl (2R*,3R*)- and (2R*,3S*)-2-(tert-butoxy-carbonylamino)-3-hydroxy-4-methyl-pentanoate (0.1 g, 0.36 mmol) was dissolved in a 6.0 M HCl solution (15 mL) and stirred at 130° C. for 1 h. The reaction mixture was extracted with Et2O (3×10 ml), and the aqueous phase concentrated under reduced pressure giving a white crude solid (0.15 g). The resulting diastereoisomeric mixture (anti:syn=8:2) was used without further purification in the following step. MS (ESI) m/z: 148 [M−H]+; (ESI) m/z: 146 [M−H]−. 1H NMR (DMSO-d6) δ 0.91 (dd, J=6.56, 10.18 Hz, 6H), 1.92 (p, J=7.10 Hz, 1H), 3.42 (d, J=8.47 Hz, 1H), 3.79-3.99 (m, 1H), 5.71 (s, 1H), 7.69-8.64 (m, 3H), 13.54 (s, 1H) (reported data refer to the major anti diastereoisomer) [see also Tetrahedron 2001, 57, 8267-8276].

Provenance & Evidence