Tetrahydrofuran → [3-(2-Pyridinylamino-carbonyl)-4-oxo-4-phenyl-butylidene]bisphosphonic acid tetraethyl ester

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Reaction Steps

The amide (II, 2.52 g), ethenylidenebisphosphonic acid tetraethyl ester (I, 3.00 g), and DBU (0.25 ml) are heated to 50° C. in THF (20 ml) for 3 hrs. The reaction is cooled, diluted with ethyl acetate, then extracted with hydrochloric acid (10%, 3×). After back washing with ethyl acetate, the acidic fraction is neutralized with saturated sodium bicarbonate, extracted with methylene chloride, dried with magnesium sulfate, and concentrated under reduced pressure. The crude material is chromatographed eluting with ethyl acetate and acetone. The resulting oil is concentrated under reduced pressure from ether to give a solid. The solid is slurried in ether, filtered and dried under reduced pressure to give the title compound, mp 104°-105°; MS (m/e) 540, 435, 420, 403, 163, 121, 105 and 94; IR (mineral oil) 1705, 1679, 1596, 1578, 1543, 1435 and 1256 cm-1 ; NMR (CDCl3) 9.77, 8.28, 8.10, 7.60, 7.47, 7.01, 5.16, 4.16, 2.65, 1.34 and 1.26 δ; CMR (CDCl3) 202.9, 195.5, 167.6, 151.1, 147.6, 138.4, 136.0, 133.7, 128.9, 128.7, 119.9, 114.1, 63.0 (m), 54.1, 34.5, 25.9 and 16.3 δ.

Provenance & Evidence