Alternative synthesis of phosphonate derivatives of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide

The phosphonates 6-methoxy-6H-dibenzo[1,2]oxaphosphinine-6-oxide and 6-(allyloxy)-6H-dibenzo[1,2]oxaphosphinine 6-oxide were synthesized in a single step under mild conditions from the H-phosphinate 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), following a method based on the oxidation with I2 of the reactant in the presence of the reactant alcohol as solvent and triethylamine as base. The compounds, of potential interest in the field of non-halogenated flame retardants, were isolated with high purity and the formulations were confirmed by multinuclear NMR spectroscopy.