Co2(CO)8-induced domino reactions of ethyl diazoacetate, carbon monoxide and ferrocenylimines leading to 2-(1-ferrocenyl-methylidene)-malonic acid derivatives

Novel 2-(1-ferrocenyl-methylidene)-malonic acid derivatives are obtained upon reacting ethyl diazoacetate, carbon monoxide and ferrocenylimines in the presence of Co2(CO)8 as catalyst under mild conditions. Presumably, the reaction involves three steps taking place in a domino fashion, (i) carbonylation of ethyl diazoacetate leading to a ketene derivative, (ii) [2+2] cycloaddition of the ketene with the ferrocenylimine present in the reaction mixture resulting in the formation of a β-lactam and (iii) N(1)-C(4) cleavage of the β-lactam ring. In most cases, 2-(1-ferrocenyl-methylidene)-malonic acid derivatives are obtained as a separable mixture of E- and Z-isomers in ratios depending on the structure of the imine component.

A domino reaction led to the E- and Z-isomers of novel ferrocenyl α,β-unsaturated amides. The selectivity of the reaction is shown to depend greatly on the nature of the substituent on the nitrogen atom.