Reductive Elimination from Cyclometalated Platinum(IV) Complexes To Form C_sp²–C_sp³ Bonds and Subsequent Competition between C_sp²–H and C_sp³–H Bond Activation

Abstract

Reductive elimination reactions of the cyclometalated platinum(IV) compounds [PtMe 2 Br{C 6 H 4 CH NCH 2 (4-ClC 6 H 4 )}L] (L = SMe 2 , PPh 3 ) to form C sp 3 −C sp 2 bonds, followed by either exclusive C sp 2 −H bond activation (L = SMe 2 ) or competition between C sp 2 −H and C sp 3 −H bond activation (L = PPh 3 ) are reported. Reductive elimination to form a C−Br bond is also reported.

Recent advances in the application of group-10 transition metal based catalysts in C–H activation and functionalization

“…Pt(IV) species are compounds known to readily undergo reductive elimination, often with initial loss of a ligand to generate a five coordinate intermediate [86]. Such a reductive elimination reaction of the cyclometalated Pt(IV) compounds was reported by Calvet and co-workers [86]. They reported a selective elimination reaction to produce C(sp 3 )−C(sp 2 ) coupling followed by cyclometalation and subsequent loss of methane (Scheme 52).…”

“…The authors, based on different analytical results, proposed that the initial C−H activation of the substrate led to carbocation generation and rearrangement to break two C−C bonds followed by catalytic releases of a bicyclic product (1,2,4,7,7a-pentahydroindene The reductive elimination reaction is often the product-forming step in both catalytic cycles and stoichiometric transformations leading to formation of C−C, C−H, or C−X bonds [86]. Pt(IV) species are compounds known to readily undergo reductive elimination, often with initial loss of a ligand to generate a five coordinate intermediate [86]. Such a reductive elimination reaction of the cyclometalated Pt(IV) compounds was reported by Calvet and co-workers [86].…”

“…They reported a selective elimination reaction to produce C(sp 3 )−C(sp 2 ) coupling followed by cyclometalation and subsequent loss of methane (Scheme 52). During the metalation, C(sp 2 )−H bond activation was observed for compound containing a smaller SMe2 ligand while competition between C(sp 2 )−H and C(sp 3 )−H bond activation was observed for the bulkier triphenylphosphine analogue [86]. toluene, and ortho-, meta-, and para-xylene, considered as "innocent" solvents were found to undergo "formal insertion" i.e.…”

Palladium‐Catalyzed Hydrobenzylation of ortho‐Tolyl Alkynyl Ethers by Benzylic CH Activation: Remarkable Alkynoxy‐Directing Effect

“…An alternative pathway from 13 to 15 may be also possible: ligation of the b-carbon atom of 13 to Zn(OAc) 2 could give 16, whose palladium ligated by acetoxy group on Zn attacks the a-carbon atom to give 15. The benzylic CÀH bond is cleaved by CMD to give the acetic-acid-coordinated palladacycle intermediate 17, [19,20] with subsequent rapid protonation of the vinyl zinc moiety by acetic acid and reductive elimination to the cis-adduct 2 i and regeneration of the palladium(0) complex and Zn(OAc) 2 . [21] It is evident that the substituents on the ethynyl carbon atom are crucial for the success of the cyclization.…”

Diarylplatinum(II) Compounds as Versatile Metallating Agents in the Synthesis of Cyclometallated Platinum Compounds with N-Donor Ligands

“…Finally, it is interesting to point out that analogous processes from cyclometallated platinum(IV) complexes obtained from dimethylplatinum(II) precursors such as [PtMe 2 X{C 6 H 4 CH=NCH 2 R'}L] (X = Cl, Br; R' = aryl; L = SMe 2 , PPh 3 ) have been recently reported [71,72]. In this case, C sp2 -C sp3 reductive elimination involving the metallated ring and one methyl ligand takes place and is followed by formation of five or six-membered platinacycles.…”