Visible-light-induced photocatalyst- and metal-free radical phosphinoyloximation of alkenes with tert-butyl nitrite as bifunctional reagent

The tert-butyl nitrite as a bifunctional reagent mediated radical alkene difunctionalization has emerged as a powerful strategy for synthesis of structurally diverse oxime-containing compounds. However, the phosphorus-centered radical initiated transformations remain largely elusive. Herein, a visible-light-induced radical phosphinoyloximation of alkenes with secondary phosphine oxides and tert-butyl nitrite has been developed under photocatalyst- and metal-free conditions. This protocol features mild conditions, broad substrate scope, good functional tolerance, and operational simplicity, yielding a diverse array of α-phosphinoyl oximes in moderate to good yields with high stereoselectivities. The photomediated homolytic cleavage of ONO bond of tert-butyl nitrite generates the reactive tert-butoxyl radical and persistent NO radical to act as both HAT reagent and the source of oximes.