Macrocyclic Pd(II) dithiolate complexes as catalysts in Heck reactions

Catalytic activity of Pd dithiolate complexes with large‐bite‐angle diphosphines in Heck coupling reactions

“…We have earlier investigated the same Heck coupling reactions using the analogous complex 4 with dppe ligand as catalyst. [31] The obtained results indicate that irrespective of aryl bromides, whether containing electron-donating group (entries 1-3), electron-withdrawing group (entries 4-6) or hetero atom (entries 7-9), the trend of catalytic activity of the complexes follows the order 2 > 3 > 4. The catalytic activity of the present complexes was compared with that of commercially available Pd complexes such as Pd(OAc) 2 , PdCl 2 (PPh 3 ) 2 , PdCl 2 (Xantphos) and PdCl 2 (Table S2).…”

“…Accordingly, complexes 2 and 3 were prepared and the catalytic activity was evaluated in the Heck coupling reactions of three different aryl bromides (Table ) in identical reaction conditions. We have earlier investigated the same Heck coupling reactions using the analogous complex 4 with dppe ligand as catalyst . The obtained results indicate that irrespective of aryl bromides, whether containing electron‐donating group (entries 1–3), electron‐withdrawing group (entries 4–6) or hetero atom (entries 7–9), the trend of catalytic activity of the complexes follows the order 2 > 3 > 4 .…”

“…Our next interest was to see the effect of lowering the catalyst loading on performance. The experiments with low loading of catalyst were carried out using the [31] coupling reaction of 4-bromoacetophenone and styrene in the presence of tetranuclear complex 2. Upon decreasing the concentration of 2 to 0.01 mol% of Pd, an excellent yield of 92% of the product was obtained ( Table 3, entry 2).…”

“…We have developed supramolecular palladium dithiolate complexes with capping ligand dppe, namely [Pd 2 (dppe) 2 {SX(C 6 H 4 ) n XS}] m (OTf) 2 m ( n = 1, 2; m = 2, 4; X = none, CH 2 ; dppe = 1,2‐bis(diphenylphosphino)ethane), as discrete molecules. These complexes showed excellent catalytic activity in Suzuki and Heck C–C coupling reactions. Recently, these dithiolate complexes have been modified by replacing dppe with wide‐bite‐angle phosphines Xantphos (9,9‐dimethyl‐4,5‐bis(diphenylphosphino)xanthenes) and dppf (1,1′‐bis(diphenylphosphino)ferrocene) (Scheme ).…”

Dppf‐Ligated Palladium Complex as an Efficient Catalyst for the Synthesis of Biaryl Ketones Using Co2(CO)8 as a C1 Source with High TON and TOF

“…Herein, we report a newly synthesized dppf ligated palladium complex [62] [Pd 2 (dppf) 2 (SC 12 H 8 S)] 2 (OTf) 4 ( Figure 2) for Suzuki-Miyaura reaction using readily available Co 2 (CO) 8 as a C1 source. It is noteworthy, that the Pd(II) complexes of aryldithiolate [Pd 2 (P \ P) 2 {S(C 6 H 4 )nS}] 2 (OTf) 4 (n = 1 or 2; P \ P = dppe, dppf and Xantphos) showed excellent catalytic activity in Suzuki-Miyaura [62,63] and Heck C-C [64] cross coupling reactions.…”