SCS-pincer palladium-catalyzed auto-tandem catalysis using dendritic catalysts in semi-permeable compartments

Abstract

Novel monometallic and dendritic SCS-pincer palladium complexes 2, 3 and 4 have been synthesized in good yields (60-89%) and high purity (palladium loading >97%). These complexes were successfully used as catalysts in the stannylation of cinnamyl chloride with hexamethylditin and in the catalytic auto-tandem reaction consisting of this stannylation followed by an electrophilic addition with 4-nitrobenzaldehyde, showing similar reaction rates and selectivities for all complexes. Dendritic complex 4 has furthermore been used in the compartmentalized catalysis of single and auto-tandem reactions, allowing catalyst reuse for four consecutive runs.

Catalytic Y-tailed amphiphilic homopolymers – aqueous nanoreactors for high activity, low loading SCS pincer catalysts

“…Weck 33–35 and co-workers have studied this extensively and several reviews have been published on the subject. 36, 37 Recently, Gebbink and van Koten 38 reported the first example of SCS-pincer Pd degradation under extremely mild reaction conditions, (e.g. low temperature, non-acidic, non-basic conditions) for the stannylation of cinnamyl chloride with hexamethylditin.…”

“…Both PVP and Hg(0) are known to selectively bind Pd(0), therefore removing it from the reaction mixture and preventing its involvement in catalysis. 34, 35, 38, 39 Figure. 6 shows that the addition of Hg(0) or PVP to the reaction mixture results in retardation of the reaction kinetics, for example at 0.2 mol% the reaction goes to completion after ca.…”

The role of the dendritic support in the catalytic performance of peripheral pincer Pd-complexes

“…In a last step, a solution of 13 was treated with 100 equivalents of crosslinked (polyvinyl)pyridine (PVPy) for 3 h. This last step was performed to chelate Pd(0) particles that might still be present as byproducts after the introduction of the palladium centers. 35 These particles could potentially lead to undesired competition in catalysis, therefore care was taken to avoid these particles in the final batch of 13. After treatment with PVPy beads, active ester SCS-pincer complex 13 was obtained in 78% yield as a pale yellow powder.…”

Nickel, palladium and platinum

“…These complexes were successfully used as catalysts in the stannylation of cinnamyl chloride with hexamethylditin. 47 The oxidation of dinuclear Pd(II) N,N-diarylformamidinates with PhIÁI 2 afforded the rare Pd(III) compounds, 19. 49…”