Triphenylphosphine → 7-{2-[3-(2-Ethoxycarbonyl-ethyl)-benzo[b]thiophen-6-yloxy]-ethyl}-3,4-dihydro-2H-[1,8]naphthyridine-1-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

Ethyl 3-(6-hydroxybenzo[b]thiophen-3-yl)propanoate (207 mg, 82.6 mmol), 7-(2-hydroxy-ethyl)-3,4-dihydro-2H-[1,8]naphthyridine-1-carboxylic acid tert-butyl ester (276 mg, 99.2 mmol) and triphenylphosphine (435 mg, 165 mmol) were dissolved in THF (15 ml) and stirred for 15 minutes under argon atmosphere at 0° C. Then, diisopropyl azodicarboxylate (0.325 ml, 165 mmol) was added to the mixture. After stirring overnight under argon, the reaction mixture was partitioned between ethyl acetate and water. The organic layer was dried with sodium sulfate, filtered and evaporated under vacuum. The crude product was chromatographied over silica gel to yield 338 mg (80%) of 7-{2-[3-(2-Ethoxycarbonyl-ethyl)-benzo[b]thiophen-6-yloxy]-ethyl}-3,4-dihydro-2H-[1,8]naphthyridine-1-carboxylic acid tert-butyl ester. NMR 1H Cl3CD δ: 7.59 (d, 1H, J=8.8 Hz), 7.33 (m, 2H), 7.00 (dd, 1H, J=2.3, 8.8 Hz), 6.93 (m, 2H), 4.42 (t, 2H, J=6.7 Hz), 4.14 (m, 2H), 3.76 (m, 2H), 3.22 (m, 2H), 3.12 (m, 2H), 2.73 (m, 4H), 1.92 (m, 2H) 1.51 (s, 9H), 1.26 (m, 3H).

Provenance & Evidence