Pyridine → Boc-L-Tyr(Tf)-OMe

Participants

Reaction Steps

Trifluoromethanesulphonic anhydride (4 ml, 23 mmol) was added to a mixture of N-Boc tyrosine methyl ester (5.9 g, 20 mmol) and pyridine (8 ml, 100 mmol) in DCM (30 ml) at 0°. After 30 min the reaction mixture was diluted with water (60 ml) and DCM (100 ml) and washed with aqueous NaOH (0.5M, 50 ml), water (60 ml), citric acid (10% solution, 2×75 ml) and water (60 ml), dried (Na2SO4) and evaporated in vacuo. Purification by column chromatography (SiO2; EtOAc/hexane, 2:1) gave the title compound (7.76 g, 91%) as a colourless oil which solidified on standing. δH (CDCl3) 7.25-7.18 (4 H, m, ArH), 5.01 (1 H, brd, CONH), 4.60 (1 H, brq, CHα), 3.71 (3 H, s, CO2Me), 3.17 (1 H, dd, J 13.8, 5.8 Hz, CHAHBAr), 3.03 (1 H, dd, J 13.6, 6.3 Hz, CHAHBAr) and 1.41 (9 H, s, tBu); m/z (ESI, 15 V) 428 (MH+).

Provenance & Evidence