A Green Nanopalladium-Supported Catalyst for the Microwave-Assisted Direct Synthesis of Xanthones

STEINGRUBER, H. SEBASTIÁN; MENDIOROZ, PAMELA; DIEZ, ALEJANDRA S.; GERBINO, DARÍO C.

SYNTHESIS-STUTTGART

GEORG THIEME VERLAG KG

Año: 2019

0039-7881

We report an efficient, selective, rapid and eco-friendly protocolfor the one-step synthesis of a small xanthone library via an intermolecularcatalytic coupling from readily available salicylaldehydes and1,2-dihaloarenes under ligand-free conditions. To achieve this advantageousdirect annulation, we used a novel recoverable palladium nanocatalystsupported on a green biochar under microwave irradiation. Unlikeother existing palladium-based approaches, our synthetic strategyshowed a greater operational simplicity, drastic reduction in reactiontimes, and an excellent tolerance to diverse functional groups. The reactionproceeds in very good yields and with high regioselectivity. Thenovel heterogeneous catalyst can be recycled and reused up to fourtimes without significant loss of activity.