Regiodivergent synthesis of pyrazino-indolines <i>vs.</i> triazocines <i>via</i> α-imino carbenes addition to imidazolidines

Abstract

formal [1,2]-Stevens and tandem Friedel-Crafts cyclizations. Of mechanistic importance, a regiodivergent reactivity was engineered through the use of a specific unsymmetrically substituted imidazolidine that promoted the exclusive formation of 8-membered ring 1,3,6-triazocines. Based on DFT calculations, an original Curtin-Hammett-like situation was demonstrated for the mechanism. Further derivatizations led to functionalized tetrahydropyrazinoindoles in high yields.

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