Aminolysis of oxime ethers in protic and aprotic solvents

Abstract

Reactions of oxime ethers with the primary amines, n-propyl-, n-butyl-, n-pentyl-, and n-hexylamine in DMSO, DMF, and MeCN are strongly catalysed by general bases. The observed secondorder rate constants (k_A) exhibit a curvilinear dependence on amine concentration leaving a positive intercept. The reactions of piperidine in DMSO follow a wholly catalysed pathway. A plot of k_Aversus[piperidine] is linear and passes through the origin. No base catalysis is observed for the reactions of n-butylamine in methanol and 1:1 (v/v) methanol–acetonitrile. The participation of the hydrogen-bond donor solvent molecule in the intermediate may account for absence of base catalysis in these solvents.