Reaction Steps
To (E)-(2R,3R,4R,5R)-3,5-Dimethoxy-2,4-dimethyl-7-tributylstannanyl-hept-6-enoic acid (5b) (85 mg, 0.17 mmol) in anhydrous DMF (1.1 ml) at 0° C. and under an atmosphere of nitrogen was added Diisopropylethylamine (0.12 ml, 0.67 mmol), followed by HATU (64 mg, 0.17 mmol). The reaction was stirred for 1.5 hours after which a solution of (S)-1-{(S)-2-((S)-2-tert-Butoxycarbonylamino-3-methyl-butyrylamino)-3-[3-(tert-butyl-dimethyl-silanyloxy)-phenyl]-propionyl}-hexahydro-pyridazine-3-carboxylic acid 3-iodo-benzyl ester (134 mg, 0.19 mmol) in anhydrous DMF (1.1 ml) was added. The reaction was warmed to room temperature, stirred for 16 hours and quenched with pH7 buffer. The reaction was extracted with dichloromethane (3×), the organics dried through a hydrophobic frit and concentrated in vacuo. The product was purified by flash chromatography (SiO2, iHex/EtOAc, 2:1) to afford 5c100 mg (57%) as a viscous oil. 1H NMR (300 MHz, CDCl3) δ 7.52 (m, 2H), 7.14 (d, J=7.6 Hz, 1H), 6.96 (t, J=7.6 Hz, 1H), 6.87 (t, J=7.6 Hz, 1H), 6.63 (m, 1H), 6.51 (m, 3H), 6.31 (t, J=8.8 Hz, 1H), 6.08 (d, J=8.5 Hz, 1H), 5.96 (d, J=19 Hz, 1H), 5.56 (m, 1H), 5.50 (dd, J=19 Hz, 7.9 Hz, 1H), 4.89 (m, 2H), 4.12 (m, 2H), 3.68 (d, J=9.4 Hz, 1H), 3.34 (d, J=10.5 Hz, 1H), 3.22 (s, 3H), 3.14 (t, J=8.8 Hz, 1H), 3.07 (s, 3H), 2.83-2.60 (m, 3H), 2.30 (m, 1H), 2.20 (m, 1H), 1.97 (m, 1H), 1.71-1.47 (m, 4H), 1.33 (m, 6H), 1.15 (m, 6H), 0.89 (d, J=7.0 Hz, 3H), 0.82-0.69 (m, 30H), 0.60 (d, J=7.0 Hz, 3H), 0.006 (m, 6H). LCMS (m/z) 1211.48 [M+H], Tr=7.29 min.
