Benzaldehyde → 1,4-Dimethyl-2-(4-methylphenoxy)-3-phenyl-1,4,2-diazaphospholidin-5-one-2-oxide

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Reaction Steps

Benzaldehyde, 0.5 mole, is added dropwise to a solution of 0.5 mole of 1,3-dimethylurea and 0.5 mole of tris(p-tolyl) phosphite in 100g of benzene as the solution was warmed from 60°-90°. Warming is continued at 90° for 3 hr, giving a reaction mixture having 31P nmr peaks at -24.2 and -21.9 ppm (~6:1 areas). The solvent and most of the by-product p-cresol are removed by stripping to 120°/0.5mm, and the remaining yellow, viscous oil is dissolved in acetone. A solid that separates is recrystallized from acetone to give a white solid: mp 126.5°-128°; 31P nmr -24.2 ppm; 1H nmr δ6.9-7.5 (m, 9, aryl), 4.6 (d, 1, J = 19Hz, PCH), 2.9 (d, 3, J = 8Hz, PNCH3), 2.7 (s, 3, NCH 3), 2.3 (s, 3, CH3); ms 330(50) (molecular ion), 273(1), 244(4), 239(6), 223(27), 182(4), 166(100), 118(49), 107(5), 91(17), 77(14), 60(42). Anal. Calcd for C17H19N2O3P: C, 61.18; H, 5.80; N, 8.48; P, 9.38. Found: C, 61.81; H, 5.67; N, 8.33; P, 9.33.

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