Water → Boc-Gly-Ala-Gly-DAla-Gly-OBzl

Participants

Reaction Steps

To a solution of Boc-Gly-Ala-Gly prepared as in Example 34B (11.0 g, 36.5 mmol) in anhydrous DMF (270 ml), was added HOBT.H2O (5.46 g, 40.4 mmol), EDC.HCl (7.74 g, 40.4 mmol), and DAla-Gly-OBzl.HCl prepared as in Example 34A (9.95 g, 36.5 mmol). The pH of the resulting solution was adjusted to ~8 (measured by spotting the reaction mixture on moistened Hydrion paper) and the reaction mixture was allowed to stir at room temperature for 12 h thereafter. The solution was concentrated in vacuo and the residue was dissolved in water (50 ml). This solution was extracted with ethyl acetate (3×100 ml). The combined ethyl acetate layers were washed with 1 N sodium bisulfate (50 ml), saturated sodium bicarbonate (50 ml) and brine (50 ml). The ethyl acetate solution was dried (magnesium sulfate), filtered and allowed to sit for 12 h undisturbed. Collection of the crystals by filtration and drying at high vacuum afforded 13.4 g (70% yield) of pure product: 1H NMR (DMSO-d6) δ 1.22 (d, J=7.2 Hz, 3 H), 1.23 (d, J=7.2 Hz, 3 H), 1.38 (s, 9 H), 3.58 (d, J=6.0 Hz, 2 H), 3.73 (d, J=4.8 Hz, 2 H), 3.91 (dd, J=6.0, 3.0 Hz, 2 H), 4.32 (m, 2 H), 5.14 (s, 2 H), 6.91 (t, J=4.8 Hz, 1 H), 7.38 (s, 5 H), 7.97 (d, J=8.1 Hz, 1 H), 8.02 (d, J=6.9 Hz, 1 H), 8.19 (t, J=5.4 Hz, 1 H), 8.33 (t, J=5.4 Hz, 1 H).

Provenance & Evidence