Non-anomalous nucleophilic reactivity of carbanions towards the nitroso group

The reactivities of a series of carbanions (several enolate and nitronate ions and the diethyl malonate anion) with the nitroso groups of N-methyl-N.-nitrosotoluene-p-sulfonamide and a variety of alkyl nitrites have been studied. The reactivity of the carbanions correlates well with their basicity over 8 pKa, units. Nitronate ions are only slightly less reactive (less than a factor of 10) than enolates of similar basicity. In general, the reactivities of the carbanions are similar to those of secondary amines of similar basicity, which contrasts with their anomalous behaviour in other chemical reactions (especially protonation processes). The causes of this non-anomalous behaviour are discussed.