Acetic Acid → HCID 135974987, compound

Participants

Reaction Steps

To a solution of compound 3 (7.3 g, 14.18 mmol) in THF (100 mL) was added a solution of 4 M HCl in dioxane (200 mL). The reaction mixture was stirred at rt and monitored with TLC and LC-MS. When all the starting material 3 was reacted, the reaction mixture was concentrated to dryness. Boc-L-phenylalanine (5, 11.3 g, 42.59 mmol) and dry dichloromethane (200 mL) and triethylamine (8.0 mL, 57.4 mmol) were added to above residua successively. The resultant solution was stirred at rt for 10 min. (benzotriazol-1-yloxy)tris(dimethylamino) phosphonium hexafluorophosphate (BOP, 18.8 g, 42.51 mmol) was added into above solution in portions. The final mixture was stirred at rt overnight. Solvent was then removed with rotavapor. To the resultant residua was added THF (200 mL) and methanol (200 mL). A solution of lithium hydroxide monohydrate (6 g, 143 mmol) in water (100 mL) was slowly added above solution. The mixture was stirred at rt for 2 hours. It was then neutralized with acetic acid (8.1 mL, 143 mmol). The mixture was diluted with ethyl acetate (˜300 mL), and washed with brine, and dried over sodium sulfate. It was filtered, concentrated and purified with silica column chromatography eluting with dichloromethane-ethyl acetate (v/v 9/1). After crystallizing with hexanes/ethyl acetate, the title compound (6, 8.52 g) was obtained as white solid in 91% yield. The title compound was obtained as a mixture of two isomers. 1H NMR (CDCl3, 500 MHz) δ 10.49 and 10.48 (both s, total 1H), 9.61 (s, 0.5H), 9.67 (s, 0.5H), 8.42 (s, 1H), 7.77 (m, 2H), 7.592 and 7.586 (both s, total 1H), 7.46 (m, 2H), 7.40-7.20 (m, 5H), 7.16-7.00 (m, 1H), 6.93 (d, 1H, J=8.0 Hz), 5.65-5.15 (m, 1.5H), 4.90 and 4.75 and 4.70 (all m, total 1H), 4.64 (m, 0.5H), 4.38 (br s, 0.5H), 3.93 (s, 3H), 3.70 (m, 0.5H), 3.02 (m, 3H), 2.64 and 2.43 and 2.23 and 1.99 (all m, total 1H), 2.35 and 2.31 (both s, total 3H), 1.85 and 1.70-1.48 and 1.35-1.10 (all m, total 4H), 1.46 and 1.44 and 1.38 (all s, total 9H). LCMS (ESI) m/z 662.05 (MH+), 605.98, 359.06 (100), 303.04; HPLC: tR=7.22 min.

Provenance & Evidence