Synthesis of (Diethoxyphosphoryl)acetonitrile Oxide and Its Cycloaddition to Olefins. Synthetic Applications to 3,5-Disubstituted 2-Isoxazolines

Abstract (Diethoxyphosphoryl)acetonitrile oxide undergoes regioselective cycloaddition to olefins leading to 3-[(diethoxyphosphoryl)methyl]-2-isoxazolines or -isoxazole. The phosphorus-stabilized carbanions generated by deprotonation of the cycloadducts can be utilized for the condensation with carbonyl compounds, alkylation, and oxidation with oxygen to provide 3,5-disubstituted 2-isoxazolines as useful synthetic building blocks. Raney nickel hydrogenolysis of 3-[(diethoxyphosphoryl)methyl]-2-isoxazolines gives β-hydroxy-β′-phosphoryl ketones bearing a variety of functional groups, which can be further converted into α,β-unsaturated β′-phosphoryl ketones.