A Mild and Efficient Palladium-Catalyzed Cyanation of Aryl Chlorides with K4[Fe(CN)6]

Reaction Scheme


The cross-coupling reactions of allylboronic acid pinacol ester derivatives with aryl and heteroaryl halides occurred with high selectivity (>97%) at the ?-carbon of the allylboron reagent in the presence of Pd-PEPPSI-IPent precatalyst and 5 M KOH in refluxing THF. In the case of trisubstituted allylboronates with different substituents on the olefin, minor olefin geometry isomer- ization was observed (E/Z ? 80/20).



In air, a Biotage 2-5mL microwave vial equipped with a stir bar was charged with Pd-PEPPSI-IPent (2 mol%), boronic ester (0.75 mmol, 1.5 equiv.), and aryl halide (0.5 mmol, 1 equiv.) at rt. The vial was sealed with a septum, evacuated (0.1 mmHg) and purged with argon (3x). Alternatively, if the aryl halide was a liquid at rt, it was added via syringe after purging with argon. THF (2 mL) was then added followed by 5M KOH (2.5 mmol, 4 equiv.), and the reaction vial was heated in an oil bath to 70�C for 24 hr. The reaction mixture was cooled to rt, extracted with Et2O (3x), and the pooled organic layers washed with brine, dried over anhydrous MgSO4, filtered, and the solvent removed in vacuo. The crude product was purified by flash chromatography.



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