Alkylation of Ketoxime with Dichloromethane Using Bases under Phase-transfer Conditions. Formation of Methylene Dioxime and Novel Heteromacrocyclic Compounds

Abstract

Abstract Ketoximes, when treated with KO2 (1 equiv) in the presence of di-μ-chlorobis(2-methylallyl)dipalladium(II) (0.1 equiv per Pd) in dichloromethane, give methylene dioximes in moderate yields. This alkylation of ketoximes with CH2Cl2 is also promoted by the use of potassium carbonate in the presence of phase-transfer catalysts such as 18-crown-6. Study on the reactivity of a series of ketoximes in these reactions shows that proton abstraction by base is a crucial step in the latter reaction. By contrast, in the former system the reactivity is supposed to be controlled by nucleophilicity of the oximate anion coordinated to palladium(II). Application of the present reaction to (E,E)-1,2-diketone dioxime such as dimethylglyoxime leads to the formation of novel 21-membered ring heteromacrocyclic compounds in which oxime units are sequentially linked by methylene bridge.