Cobalt‐Catalyzed Dual Annulation of o‐Halobenzaldimine with Alkyne: A Powerful Route toward Bioactive Indenoisoquinolinones

Publisher： John Wiley & Sons Inc

E-ISSN： 1521-3765|21|26|9544-9549

ISSN： 0947-6539

Source： CHEMISTRY - A EUROPEAN JOURNAL, Vol.21, Iss.26, 2015-06, pp. : 9544-9549

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Abstract

AbstractA cobalt‐catalyzed dual annulation reaction for the synthesis of variously substituted indenoisoquinolinones from 2‐bromobenzaldehydes, amines, and methyl 2‐(ethynyl)benzoates has been developed. This method could also be applied to the synthesis of an array of highly functionalized bioactive indenoisoquinolinones and their derivatives. A possible mechanism of the cobalt catalysis is proposed, involving imine formation from bromobenzaldehyde and the amine, followed by a series of oxidative addition, alkyne insertion, cyclization reactions, and carbon–carbon double‐bond migration. The regioselective alkyne insertion plays an important role for the success of the second annulation.