Cobalt complex Co(nmp)2 can efficiently catalyze the aerobic oxidative 5-exo cyclization of β,γ-unsaturatedoximes to afford isoxazolines. The key cyclization step involves the generation of carbon-centred radicals. The products are largely dependent on the reaction conditions. The oxidative termination products 2 were produced predominantly when the reaction was carried out in i-PrOH, whereas the