Intramolecular Transmetalation of Arylpalladium(II) and Arylplatinum(II) Complexes with Silanes and Stannanes

Abstract

The oxidative addition of o-(Me 2 RSiCH 2 O)C 6 H 4 I (R ) Me, Ph, F) to palladium(0) complexes [Pd(PPh 3 )], [Pd(dba)(AsPh 3 ) 2 ] (dba ) dibenzylideneacetone), and [Pd(dba)(L 2 )] [L 2 ) 1,1′-bis(diphenylphosphino)ferrocene (dppf), 2,2′-bipyridine (bpy), o-phenanthroline (phen)] leads to the corresponding complexes o-(Me 2 RCH 2 O)C 6 H 4 Pd(L 2 )I (L ) PPh 3 , AsPh 3 ; L 2 ) dppf, bpy, phen). This Pd(II)/Si transmetalation, the key step in the Hiyama cross-coupling reaction, proceeds smoothly with different fluorides as the promoters. Additionally, silver and potassium carbonate promote the transmetalation by the likely formation of an intermediate with a Pd-O bond. The related Pt(II)/Sn and Pt(II)/Si transmetalation leads to the formation of stable oxaplatinacycles. In contrast with the requirement of additives for the Pd(II)/Si transmetalation, the transmetalation of Pt(II) complexes proceeds directly in the absence of additives. Additionally, [Pt(PPh 3 )] 4 was shown to behave as a moderate catalyst for the cross-coupling of two aryl triflates with ethenyltributylstannane to form the corresponding styrenes.

Machine learning meets volcano plots: computational discovery of cross-coupling catalysts

“…125 – 128 On the other hand, Pt catalysts are virtually experimentally unknown 129 and those that have been tested tend to show only moderate catalytic ability. 130 Nonetheless, their significant presence on the volcano plateau does align with our earlier DFT-based evaluations. 39 – 41 Indeed, we previously postulated that the presence of Pt based catalysts on top of the volcano may indicate that the problem with these species is less thermodynamic and more kinetic in nature.…”

Mechanistic Significance of the Si–O–Pd Bond in the Palladium-Catalyzed Cross-Coupling Reactions of Alkenylsilanolates

“…Treatment of iodophenoxystannane 2 with [(dppf)Pd(dba)] complex results in oxidative addition of the aryl iodide to generate 3 . 13 Addition of Ag 2 CO 3 promotes the intramolecular transmetalation step, and the resulting complex 4 can be isolated. Similarly, treatment of iodophenoxysilane 5 with [(Ph 3 As) 2 Pd(dba)] affords the trans-ligated complex 6 .…”

Transmetallation Reactions Involving Group 10 Metals

“…In an extension of this work it was shown that the corresponding platinum system undergoes an intramolecular transmetallation from both a silane and a stannane in the absence of activator, cf. Equation 18 [94]. Cl (16) The use of other activators was also reported by Denmark [95].…”