Syntheses of Sterically Shielded Stable Carbenes of the 1,2,4-Triazole Series and their Corresponding Palladium Complexes: Efficient Catalysts for Chloroarene Hydrodechlorination

The new sterically shielded 1,3,4-trisubstituted 1,2,4-triazol-5-ylidenes 8b-d were synthesized by a three step method starting from 2-phenyl-1,3,4-oxadiazole. The syntheses of palladium complexes 9a-d and 10a-d (including the sterically shielded derivatives 9c,d and 10a-d) were carried out via the reactions of the stable carbenes 8a-d with palladium halogenide salts in THF or toluene solution. Complexes 9c,d and 10a-d were found to be excellent catalysts for the reductive dechlorination (hydrodechlorination) of p-dichlorobenzene. The structures of 8c, 9a,b, and 10a were determined by single-crystal X-ray diffraction.Ukrainian Academy of Sciences 118Robert A. Welch Foundation F-0003Chemistr