Oximate anion as a powerful neighbouring group towards saturated carbon

Abstract

We have found that the Mannich base oxime methiodides (IIa) and (IIb) undergo elimination (to yield vinyl oximes) and cyclisation (to yield 2-isoxazolines) in a range of protic solvents and their lyate ions. In general, reaction in water favours elimination and reaction in t-butyl alcohol gives exclusive cyclisation. By blank runs with a series of possible intermediates, we have established that the cyclisation to form 2-isoxazolines is truly anchimeric. We confirmed this by using α-deuteriated Mannich base oxime methiodides which could be cyclised without appreciable loss of deuterium.