Hydrochloric Acid → (S)-2-amino-6-borono-2-ethylhexanoic acid hydrochloride

Participants

Reaction Steps

A solution of (S)-methyl 2-(tert-butoxycarbonylamino)-2-ethyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)hexanoate (0.283 g, 0.709 mmol) in 6 N HCl (5 mL) was heated to a gentle reflux for 16 h. After cooling to room temperature, the reaction mixture was transferred to a separatory funnel, diluted with deionized water (5 mL) and washed with dichloromethane (3×10 mL). The aqueous layer was concentrated to give an off-white solid that was dissolved in deionized water (3 mL) and passed through a C-18 Isolute SPE column (20 g) eluted with 10% methanol in deionized water (200 mL). The fractions containing product were concentrated under reduced pressure, redissolved in deionized water (5 mL), frozen in liquid nitrogen and lyophilized to give (S)-2-amino-6-borono-2-ethylhexanoic acid hydrochloride as an white foam (0.096 g, 67%). 1H NMR (D2O, 300 MHz) δ□ (m, 4H), 1.31-1.17 (m, 3H), 1.13-0.97 (m, 1H), 0.794 (t, J=7.6 Hz, 3H), 0.63 (t, J=7.8 Hz, 2H); ESI-LCMS m/z calcd for C8H18BNO4: 203.1. found 204.1 (M+1)+.

Provenance & Evidence