Ru(II)-Catalyzed Annulation of 2-Nitrostyrenes: Alcohols as Hydrogen Source and Alkoxylating Reagent
Bo Deng1, Rui Zhang1, Jiule Shi1
1Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, National Demonstration Center for Experimental Chemistry Education, College of Chemistry& Materials Science, Northwest University, 1 Xuefu Road, Xi'an, Shaanxi710127, P. R. China.
Abstract:
A new Ru(II)-catalyzed annulation pathway of 2-nitrostyrenes, distinct from the conventional 6π-electrocyclization, has been developed. This transformation employs alcohols as both the hydrogen source and alkoxylating reagent, enabling the efficient synthesis of 3-alkoxy-1H-indoles. Mechanistic studies reveal that this domino transformation proceeds via four key steps: Michael addition of the enone moiety, nitro reduction, cyclization, and dehydration. Moreover, the vicinal alkoxy group acts as a critical determinant for preserving the carbonyl group under the reductive conditions.
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