TfOH-Catalyzed Intramolecular Annulation of 2-(Aryl)-Phenyl-Substituted p-Quinone Methides under Continuous Flow: Total Syntheses of Selaginpulvilin I and Isoselagintamarlin A

In this article, we describe a convenient method to access 9-aryl fluorene derivatives through a TfOH-catalyzed intramolecular 1,6-conjugate arylation of 2-(aryl)-phenyl-substituted p-quinone methides (QMs) under continuous flow using the microreaction technique. This method was found to be very effective for most of the p-QMs, and the corresponding 9-aryl fluorene derivatives were obtained in moderate to excellent yields. Moreover, this protocol was further elaborated to the first total syntheses of selaginpulvilin I and isoselagintamarlin A.