Pd NPs Decorated on POPs as Recyclable Catalysts for the Synthesis of 2-Oxazolidinones from Propargylic Amines via Atmospheric Cyclizative CO2 Incorporation

A novel approach has been taken for the synthesis of a microporous polymeric materials of BBA-1 and BBA-2 (benzene-benzylamine), which is a POP (porous organic polymer) with its excellent surface area determined by BET study, via Friedel-Crafts alkylation of benzene and benzylamine (or 4-methoxybenzylamine) by utilizing a cross-linker (formaldehyde dimethyl acetal) and a promoter (anhydrous FeCl3). Pd NPs were decorated over BBA-1 and modified BBA-2 to generate the desired catalysts (Pd@BBA-1 and Pd@BBA-2 respectively). The characterizations of the synthesized nanomaterials have been conducted by FE-SEM, wide-angle powder XRDmethods, N-2 adsorption/desorption studies and high resolution transmission electron microscopy (TEM). Pd NPs decorated porous polymers are described here to facilitate the carboxylative cyclization of several propargylamine derivatives leading to the corresponding desired products (2-oxazolidinone) under the application of ambient conditions (0.1 MPa of CO2, DMSO, 40-80 degrees C, 30-60 mg nanocatalyst). The Pd NPs-loaded POP is competitive with previously reported catalytic systems. These pure polymeric microporous catalytic systems exhibited outstanding catalytic performances for the generation of oxazolidinones from several propargylic amines in the absence of organic and inorganic bases through atmospheric cyclizative CO2 incorporation. The modified nanocatalyst (Pd@BBA-2) displayed exceptional recycling efficiency for the generation of oxazolidinones up to five runs without any noticeable decay in the activity of Pd@BBA-2.