Nitrosamine, lithiation

The interesting "dimerization of lithiated N-nitrosamines to cyclic tetrazene N-oxides has been described (U8) and provides another route to the novel cyclic tetrazenes (U9, 0) A radical path has been suggested for this reaction [Scheme h] ( ). 

This is currently the only method that allows reversible enhancement of the acidity of a-nitrogen CH-protons in a large variety of secondary amines using the nitroso group on the nitrogen (X = NO, see examples in Table I). The nucleophile 2 is synthetically equivalent to an a-aminocarbanion 4 while the inherent reactivity at carbons next to amino nitrogens is electrophilic (see the immonium ion 5).8,9 Lithiated nitrosamines are also useful because their... 

Oxygenation of lithiated dialkylnitrosamines in THF at—78°C is fast and gives good yields of the A-alkyl-A-(l-hydroperoxyalkyl)nitrosamines. If oxygenation is too prolonged, poor yields and explosive by-products result. 

Nitrosamines are ambident acceptors which can react at O, N, or a-H. The observation (90) that a-lithiation of Me2NNO is most effective with the harder... 

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