Bsi(OTf)3-mediated tandem annulation of 1-aryl isochroman-3-ones with oxygenated arenes: one-pot synthesis of polyoxygenated homotriptycenes

Diastereoselective Cascade Double Michael Addition to Access Bridged Coumarins, Oxindoles and Spirooxindoles: A Sustainable Strategy for Synthesis of Anticancer Molecules

An efficient and concise synthesis of highly functionalized bridged coumarins has been developed through a diastereoselective double Michael addition reaction of p-quinols with various 4-hydroxy coumarins under catalyst-free conditions in H2O-DMSO (8 : 2). The method has been applied to oxindoles for the synthesis of a variety of bridged-oxindoles and bridged-spiroxindoles in presence of a DABCO base using H2O-EtOH (8 : 2) as solvent medium. The strategy is simple, highly atom economical as there is no by-product and environmentally benign (E-factor=0.1-0.9). The synthesized compounds were screened against triple-negative breast cancers and found that bridged coumarin (3 a) and oxindole (5 d) compounds exhibit potent anti-cancer activity at 6.6 and 8.8 μM (IC50) concentrations respectively. Further analysis revealed that 3 a and 5 d caused elevated early and total apoptosis by arresting the MDA-MB-468 cells in G2/M phase of the cell cycle. Overall, our results demonstrate that bridged coumarin (3 a) and oxindole (5 d) compounds-based approach attenuates the cancer progression and may pave a path for the translational outcome.

One-pot synthesis of sulfonyl dibenzosuberdiones via In(OTf)3-promoted double Friedel-Crafts reactions of oxygenated arylacetic acids with β-arylvinyl sulfones

Under open-vessel atmosphere conditions, a one-pot easy-to-operate method for the construction of diverse sulfonyl dibenzosuberdiones is developed via In(OTf)₃-promoted tandem double Friedel-Crafts reactions of oxygenated arylacetic acids with β-arylvinyl sulfones. A plausible mechanism is proposed and discussed in detail. This protocol allows for highly effective sequential intermolecular Michael addition, intramolecular ring-closure and α-benzylic oxidation via the formation of two carbon-carbon single (C-C) bonds and one carbon-oxygen double (CO) bond.