2,3-dihydro-1-methyl-1H-phosphole 1-oxide synthesis

Yield:-

Reaction Conditions:

with dihydrogen peroxide;potassium in water

Steps:

4 EXAMPLE 4
EXAMPLE 4 116 g of 1-methyl-1-oxo-3-phospholene (1.0 mole), 270 ml of water and 78 mg of potassium osmate are mixed and the resulting mixture is heated to 70° C. 49 g of a 35% hydrogen peroxide solution (0.505 mole) are then added dropwise over a period of 10 minutes. The highly exothermic reaction is stabilized by external cooling. The reaction temperature is then maintained for 3 hours, followed by concentration by evaporation in vacuo at a maximum sump temperature of 80° C. According to the ¹ H-NMR-spectrum, the liquid yellow residue consists, as expected, of a 1:1-mixture of 1-methyl-1-oxo-3-phospholene and 1-methyl-1-oxo-3,4-dihydroxy phospholane. After a few days, the 1-methyl-1-oxo-3,4-dihydroxy phospholane begins to crystallize out. The two components are separated by the addition of 100 ml of methylene chloride. 1-Methyl-1-oxo-3,4-dihydroxy phospholane (74 g) is left behind in the form of a yellow crystal sludge. 1-Methyl-1-oxo-phospholene (56 g) is obtained in pure form after concentration of the methylene chloride phase and vacuum distillation.

References:

Bayer Aktiengesellschaft US4102949, 1978, A