Thioglycolic Acid → (S)-3-{(S)-2-[4-(3,4-Dichloro-benzyloxy)-phenyl]-2,3-dihydro-benzo[1,4]dioxin-6-yl}-2-((S)-1-phenyl-propylamino)-propionic acid methyl ester

Participants

Reaction Steps

(S)-3-{(S)-2-[4-(3,4-Dichloro-benzyloxy)-phenyl]-2,3-dihydro-benzo[1,4]dioxin-6-yl}-2-[(4-nitro-benzenesulfonyl)-((S)-1-phenyl-propyl)-amino]-propionic acid methyl ester (1.8 g) was dissolved in 30 mL dry DMF, then 505 μL (670 mg) mercaptoacetic acid and 2.6 mL (2.6 g) DBU were added at rt. The reaction stirred for 3 h, then was partitioned between saturated aqueous NaHCO3 and diethyl ether. The organic layer was washed successively with aqueous NaHCO3, water, and brine, then was dried with Na2SO4 and evaporated. The residue was purified by silica gel flash chromatography (9:1 to 8:2 hexanes/EtOAc) to give 893 mg desired product after drying. 1H NMR (400 MHz, acetone-d6): 7.71 (d, 1H), 7.61 (d, 1H), 7.50-7.42 (m, 3H), 7.27-7.15 (m, 5H), 7.09 (m, 2H), 6.80 (d, 1H), 6.67 (d, 1H), 6.61 (m, 1H), 5.19 (s, 2H), 5.10 (m, 1H), 4.34 (m, 1H), 4.02 (m, 1H), 3.63 (s, 3H), 3.47 (t, 1H), 3.15 (t, 1H), 2.75 (m, 2H), 2.10 (s, 1H), 1.69-1.48 (m, 2H), 0.78 (t, 3H).

Provenance & Evidence