An investigation in the isoxazole series

The hydrogen atoms in the CH₃ groups in position 5 of 3,5-dimethyl-4-nitroisoxazole (I) and 3,5-dimethyl-4-phenylazoisoxazole (II)undergo isotopic exchange with diethyl[D]amine. The position of entry of the deuterium has been established and the CH₃ groups of compounds I and II have been characterized by NMR spectroscopy. The possibility of a correlation of the reactivities of the methyl groups with their chemical shifts is discussed.For part XX, see [1].