Mechanistic Investigation and New Catalyst Design in Palladium- and Platinum-Catalyzed Se−Se Bond Addition to Alkynes

Abstract

The present study explains the different catalytic activities of platinum and palladium in Se−Se addition reactions with alkynes. Under the catalytic conditions cis-[Pt(SePh)2(PPh3)2] undergoes fast isomerization to the trans isomer, which does not react with alkynes. Palladium complexes maintain their catalytic activity, due to the formation of the dinuclear structure [Pd2(SePh)4(PPh3)2]. It was shown that the palladium intermediate involved in the catalytic cycle can be prepared directly in the reaction mixture starting from the simple [PdCl2(PPh3)2] precursor, thus allowing replacement for the traditional Pd(PPh3)4 catalyst. X-ray analysis shows that the products of Se−Se addition reactions with alkynes possess the necessary geometry parameters for coordination as bidentate ligands.

Catalyst Leaching as an Efficient Tool for Constructing New Catalytic Reactions: Application to the Synthesis of Cyclic Vinyl Sulfides and Vinyl Selenides

“…Better results were obtained with PPh 3 and PCyPh 2 (19 %, entries 3, 4) as well as DPPM, which gave 35 % of 5a (entry 5). More promising results were observed with several other phosphane ligands (45-53 %, entries [6][7][8] and the phosphite ligand P(OiPr) 3 (65 %, entry 9). The best results, however, were achieved with PCy 2 Ph, which gave complete conversion of 4a under these conditions (entry 10).…”

Platinum Complexes of Aromatic Selenolates

“…2,7-di-tert-butylnaphtho [1,8-c,d] [1,2]diselenole (dt-Se 2 naph), 2-tert-butylnaphtho [1,8-c,d] [1,2]diselenole (mt-Se 2 naph), and 4,7-dibromo-2-tert-butylnaphtho [1,8-c,d] [1,2]diselenole (Br 2 -mt-Se 2 naph). These compounds can be used as ligands, by reducing the Se-Se bond needs to forming dianionic 10,11,14 These complexes are very similar around the Pt(II) metal center despite the flexibility of the backbone.…”

Nickel(II) Chloride‐Catalyzed Regioselective Hydrothiolation of Alkynes

“…The structure and stereochemistry of the products were proven with 2D COSY-LR and NOESY spectra as described earlier. [20] All 2D spectra were recorded using inverse triple resonance probehead with active shielded Z-gradient coil.…”