Dilithium Enediamide Derived From a 1,4‐Diaza‐1,3‐diene: Reactivity of a Strongly N‐Basic, Highly C‐Nucleophilic Compound Toward C–H Acids

The lithium enediamide complex [{(THF) 2 Li} 2 ( t Bu‐DAD)] ( t Bu‐DAD t BuNCHCHN t Bu) exhibits pronounced basic and nucleophilic reactivity. C–H‐acidic diethyl malonate derivatives RCH(COOEt) 2 (RH, Ph) are readily deprotonated to give resonance‐stabilised carbanions [RC(COOEt) 2 ] − . The resulting increase in electrophilicity at the carbonyl carbon atoms enables subsequent reaction with the enediamide dianion. In the case of CH 2 (COOEt) 2 , this transformation can be viewed as electrophilic substitution at the enediamide unit, leading to C–C bond formation between one of the CC carbon atoms and the ester carbonyl carbon atoms. In contrast, the reaction with PhCH(COOEt) 2 corresponds to electrophilic addition to the enediamide CC bond. Steric effects of the phenyl substituent further induce rearrangement of the N–C–C–N framework into an N–C–N–C connectivity within one enediamide unit. Unlike the reactions with other esters, no electron transfer to the diethyl malonate derivatives is observed. Phenylacetylene is likewise deprotonated but subsequently undergoes a cascade of transformations, including enamine alkynylation and hydrovinylation, to yield a lithium complex featuring a 1,2‐diamidoethane fragment and an enamide–amine moiety linked by a phenylvinylidene unit. Notably, no redox activity of the enediamide unit is observed in these reactions either.