Generation of nitrite oxides via O-tributylstannyl aldoximes; application to the synthesis of isoxazolines and isoxazoles

Nitrite oxides were generated readily by the reaction of aldoximes 1, with tert-butyl hypochlorite and bis(tributyltin) oxide. The reaction proceeded efficiently under mild conditions, in which O-stannylated aldoximes 2 are thought to be key intermediates. This reaction system was applicable to the one-pot syntheses of isoxazole derivatives 4 and 5 in the presence of dipolarophiles via a [3 + 2] cycloaddition.