Reaction Steps
A mixture of N-Boc-4-iodo-L-phenylalanine methyl ester (810 mg, 2 mmol, Lei, H et al, ibid) tetrakis(triphenylphosphine)palladium (0) (231 mg, 0.2 mmol), aqueous sodium carbonate (4 mmol, 2 ml of a 2M solution) and diethyl(3-pyridyl)borane (294 mg, 2 mmol) in dimethoxyethane (30 ml) was refluxed for 6 hr. The solvent was removed in vacuo, the residue dissolved in EtOAc (100 ml) and washed with water (30 ml) aqueous sodium thiosulphate (20 ml) and brine (30 ml) dried (Na2SO4)and evaporated in vacuo. Purification by column chromatography (SiO2, EtOAc/hexane 30:70) gave the title compound (335 mg,47%) as a yellow oil. δH (CDCl3) 8.81 (1 H, d, J 1.7 Hz, PyrH), 8.56 (1 H, dd, J 4.8, 1.6 Hz, PyrH), 7.84 (1 H, dt, J 7.9, 2.0 Hz, PyrH), 7.49 (2 H, d, J 8.2 Hz, ArH), 7.34 (1 H, ddd, J 7.9, 4.8, 0.6 Hz, PyrH), 7.23 (2 H, d, J 8.2 Hz, ArH), 5.09 (1 H, br d, J 7.8 Hz, CONH), 4.62 (1 H, br q, J 6.8 Hz, CHα), 3.73 (3 H, s, CO2Me), 3.18 (1 H, dd, J 13.8, 5.6 Hz, CHAHBAr), 3.07 (1 H, dd, J 13.8, 5.8 Hz, CHAHBAr) and 1.40 (9 H, s, tBu); m/z (ESI, 15 V) 357 (MH+).
