Styrene → Stilbene

Participants

Reaction Steps

Dimethylformamide (Aldrich) was used in anhydrous form. All the aryl bromides, iodobenzene and alkene substrates were purified before use (Aldrich). 6.0 mmol each of styrene and bromobenzene, 6.6 mmol of NaOAc (base) were mixed with 50 ml of DMF (dimethylformamide). 20 ml of this solution was placed in a 50 ml round bottom-flask equipped with a magnetic stirring bar and condenser connected to a vacuum line. The solution was flushed five times with nitrogen using a vacuum nitrogen cycle. The catalysts prepared in Example 12, generations 0 through 4, were then added. The autoclave was placed in an oil bath and the 120° C. was reached by stirring on a hot plate. After the appropriate reaction time, the reaction was allowed to cool to room temperature. The resulting solution was filtered to remove the catalyst. The filtrate was extracted with diethyl ether (4×40 ml), and the ether extracts were washed with brine and distilled water, followed by drying over magnesium sulfate. The product, trans stilbene, was analyzed by 1H NMR spectroscopy and/or gas chromatography, and identified by comparison of spectral results with literature data. Results are shown in Tables 6-7 below. The yields of stilbene was significantly less when generation 3 and 4 dendrimer complexes are used as catalysts. The best turnovers in terms of molecules of trans-stilbene formed per mol of palladium was achieved with the generation 2 catalyst.

Provenance & Evidence