Synthesis of oxime ethers via a formal reductive O-H bond insertion of oximes to -keto esters

This study describes an efficient approach to access oxime ethers via P(III)-mediated O-H bond insertion reaction of oximes with alpha-keto esters. The strategy involves the protonation of in situ generated Kukhtin-Ramirez adducts, followed by S(N)2-type reaction. Important features include a good functional group tolerance, operational simplicity, and application to gram scale synthesis and the synthesis of an acaricide.