Tetrahydrofuran → (4-Anilino-3-benzoyl-4-oxobutylidene)bisphosphonic acid tetraethyl ester

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Reaction Steps

The amide (II, 2.50 g), ethenylidenebisphosphonic acid tetraethyl ester (I, 3.00 g), and DBU (0.25 ml) are heated to 50° C. in THF (20 ml) for 30 min. The reaction is cooled, diluted with ethyl acetate, washed with hydrochloric acid (1N), saturated sodium bicarbonate, and saline, then dried with magnesium sulfate, and concentrated under reduced pressure. The crude material is chromatographed eluting with ethyl acetate. The compound is left overnight on the bench whereupon a solid formed. This is slurried in ether, filtered and dried in under reduced pressure to give the title compound, mp 104°-105°; MS (m/e) 539, 447, 288, 239, 163, 120, 105 and 93; IR (mineral oil) 1699, 1682, 1606, 1599, 1589, 1549, 1442 and 1241 cm-1 ; NMR (CDCl3) 9.55, 8.08, 7.57, 7.46, 7.30, 7.09, 4.96, 4.17, 2.58, 1.38 and 1.28 δ; CMR (CDCl3) 212.4, 195.5, 167.1,138.0, 136.2, 133.7, 128.9, 128.8, 128.5, 124.3, 119.6, 63.1 (m), 54.0, 34.5, 25.9 and 16.3 δ.

Provenance & Evidence