Phosphorus oxide (P4O10) → HCID 69129823, compound

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Reaction Steps

Phosphorus pentoxide (22.5 g) was added with stirring to a solution of 3,5-dibromo-4-oxopentanoic acid (30.4 g, 0.11 mol) in dry dichloromethane (500 ml). The mixture was heated at reflux with stirring for 2 h, and cooled to room temperature. The resulting mixture was filtered through a pad of filter aid, washed with brine, dried over sodium sulfate and evaporated to yield the tetrahydrofuranone (mixture of Z- and E-isomers in 4:1 ratio) as a pale yellow oil (23.4 g, 82%). The oil solidified on standing at room temperature overnight. Crystallisation from dichloromethane/light petroleum (60-80° C.) gave an analytically pure sample of the Z-isomer. m. p. 79° C. νmax 3094, 3027, 2947, 1799, 1634, 1393, 1289, 1114, 949, 838, 747, 718, 660 cm−1. λmax 279 nm (ε 4938). 1H n.m.r. δ (CDCl3) 3.10, dd, J 2.3 Hz, 18.8 Hz, Ha3; 3.45, dd, J 7.9 Hz, 18.8 Hz, Hb3; 5.07, m, H4; 5.90, s, 5-CHBr. 13C n.m.r. δ (CDCl3): 37.2, C3; 40.5, C4; 86.9, 5-CHBr, 152.3, C5; 169.5, C2.

Provenance & Evidence