One-Pot Catalytic Cleavage of C═S Double Bonds by Pd Catalysts at Room Temperature

Abstract

The C═S double bonds in CS and thioketones were catalytically cleaved by Pd dimeric complexes [(NN)Pd(NO)](NO) (NN, 2,2'-bipyridine, 4,4'-dimethylbipyridine or 4,4'-bis(trifluoromethyl)) at room temperature in one pot to afford CO and ketones, respectively, for the first time. The mechanisms were fully investigated by kinetic NMR, isotope-labeled experiments, in situ ESI-MS, and DFT calculations. The reaction is involved a hydrolytic desulfurization process to generate C═O double bonds and a trinuclear cluster, which plays a pivotal role in the catalytic cycle to regenerate the dimeric catalysts with HNO. Furthermore, the electronic properties of catalyst ligands possess significant influence on reaction rates and kinetic parameters. At the same temperature, the reaction rate is consistent with the order of electronegativity of NN ligands (4,4'-bis(trifluoromethyl) > 2,2'-bipyridine > 4,4'-dimethylbipyridine). This homogeneous catalytic reaction features mild conditions, a broad substrate scope, and operational simplicity, affording insight into the mechanism of catalytic activation of carbon sulfur bonds.

Pd-Catalyzed Assembly of Fluoren-9-ones by Merging of C–H Activation and Difluorocarbene Transfer

“…Fluoren-9-one 3a could be easily converted into 9 H -fluoren-9-ol 5 and 9-methyl-9 H -fluoren-9-ol 6 in 95% and 88% yields, respectively. , In addition, 3a could also be reduced into 9 H -fluorene 7 in high yield using the hypophosphorous acid–iodine reducing system . According to the reported literature, 9 H -fluoren-9-amine 8 , 9 H -fluorene-9-thione 9 , and 6 H -benzo­[ c ]­chromen-6-one 10 could be readily acquired from 3a in one or two steps as well. − …”