Access to silica- and monolithic polymer supported C-C-coupling catalysts via ROMP: applications in high-throughput screening, reactor technology and biphasic catalysis

摘要

N,N-Di(pyrid-2-yl)norborn-2-ene-5-ylcarbamide (1) and N,N-di(pyrid-2-yl)-7-oxanorborn-2-ene-5-ylcarbamide (3) were used for the synthesis of the corresponding dichloropalladium(II) complexes, N-(norborn-2-ene-5-ylcarboxyl)-N,N-di(pyrid-2-yl)amine dichloropalladium(II) (2) and N-(7-oxanorborn-2-ene-5-ylcarboxyl)-N,N-di(pyrid-2-yl)amine dichloropalladium(II) (4), respectively. The structures of 3 and 4 were determined by X-ray crystallography. Using Mo(N-2,6-Me-2-C6H3)(CHCMe2Ph)(OC-Me(CF3)(2))(2), 1 was surface-grafted onto various silica-based carriers. Poly-1 was additionally used for the coating of silica and ROMP-derived monolithic supports. Heck systems were generated by loading of the corresponding dipyridylamide-functionalized supports with Pd(II). Alternatively, monolithic Pd-loaded supports were synthesized by an in situ grafting of 4 onto a ROMP-derived monolithic support. Finally, 4 was copolymerized with 7-oxanorborn-2-ene-5,6-dicarboxylic anhydride to yield a water-soluble Heck coupling-active copolymer suitable for biphasic catalysis. All supports were successfully tested in the coupling of selected aryliodides and arylbromides under various conditions including flow-through systems, cartridges, biphasic catalysis and microwave-assisted synthesis. Selected data including turn-over numbers (TONs) and frequencies (TOFs) are presented. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 53]