title: Metal-Free Dehydrogenative Diels-Alder Reactions of 2-Methyl-3-Alkylindoles with Dienophiles: Rapid Access to Tetrahydrocarbazoles, Carbazoles, and Heteroacenes.
abstract: An unprecedented strategy for in situ generation of indole-based ortho-quinodimethanes (oQDMs) from 2-methyl-3-alkylmethylindoles by either a metal-free DDQ- or BQ-mediated dehydrogenative process was developed. These oQDMs were trapped by electron-deficient dienophiles to provide a facile approach to synthetically valuable tetrahydrocarbazoles, carbazoles, and hetereoacenes. The salient features of this transformation include direct C(sp(3))-H bond functionalizations, readily available starting materials, metal-free conditions, high efficiency, operational simplicity, and ease of scale-up.
authors.affiliation: Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200062 (China).
authors.forename: Liejin
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200062 (China).
authors.forename: Bing
authors.initials: B
authors.lastname: Xu
authors.affiliation: Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200062 (China). jlzhang@chem.ecnu.edu.cn.|State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, CAS, 345 Lingling Road, Shanghai 200032 (China). jlzhang@chem.ecnu.edu.cn.
authors.forename: Junliang
authors.initials: J
authors.lastname: Zhang
keywords: CH activation; cycloaddition; heterocycles; oxidation; synthetic methods