Bimetallic catalysis for C-C and C-X coupling reactions

Abstract

Bimetallic catalysis represents an alternative paradigm for coupling chemistry that complements the more traditional single-site catalysis approach. In this perspective, recent advances in bimetallic systems for catalytic C-C and C-X coupling reactions are reviewed. Behavior which complements that of established single-site catalysts is highlighted. Two major reaction classes are covered. First, generation of catalytic amounts of organometallic species of e.g. Cu, Au, or Ni capable of transmetallation to a Pd co-catalyst (or other traditional cross-coupling catalyst) has allowed important new C-C coupling technologies to emerge. Second, catalytic transformations involving binuclear bond-breaking and/or bond-forming steps, in some cases involving metal-metal bonds, represent a frontier area for C-C and C-X coupling processes.

Scheme 1. Representative mechanistic schemes for bimetallic catalysis (a) without and (b) with binuclear bond breaking and forming events.

Scheme 2. Cu/Pd cooperation in Sonogashira coupling.

Scheme 3. General scheme for organocopper nucleophiles generated by element-cupration.

Scheme 4. Borylcupration of styrenes demonstrated by Sadighi.

Scheme 5. Cu/Pd catalysis for arylboration developed by the groups of Semba/Nakao and Brown.

Scheme 6. Diastereoselective carboboration developed by Brown.

Scheme 7. Enantioselective carboboration developed by Liao.

Scheme 8. Cu/Ni catalysis developed by Semba/Nakao.

Scheme 9. Hydroarylation catalysis developed by Semba/Nakao.

Scheme 10. Enantioselective hydroarylation developed by Buchwald.

Scheme 11. Reductive allylation of α,β-unsaturated ketones developed by Riant.

Scheme 12. Silylation catalysis developed by Riant.

Scheme 13. Cu/Pd cross-coupling developed by Faul.

Fig. 1. Alkylsilane reagent developed by Nakao.

Scheme 14. Cu/Pd variant of Hiyama–Denmark coupling developed by Nakao.

Scheme 15. Cu/Pd-catalyzed imine synthesis.

Scheme 16. Au/Pd catalysis developed by Blum.

Scheme 17. Au/Pd catalysis for lactone formation developed by Blum.

Scheme 18. Au/Pd catalysis developed by Nevado.

Scheme 19. Au/Pd mechanistic results from Blum.

Scheme 20. Rh/Pd catalysis developed by Lee.

Scheme 21. V/Pd catalysis developed by Trost.

Scheme 22. Ti/Ni catalysis developed by Weix.

Scheme 23. Ni/Pd catalysis developed by Weix.

Scheme 24. Ag/Pd catalysis developed by Goossen.

Scheme 25. Fe/Pd catalysis developed by Chen and Ma.

Scheme 26. (a) Asymmetric epoxide ring-opening catalysis developed by Jacobsen; (b) heterobimetallic catalyst design of Shibasaki.

Scheme 27. Oxidative catalysis involving dipalladium(iii) intermediates identified by Ritter.

Scheme 28. Bimetallic mechanism for Ag-catalyzed fluorination proposed by Ritter.

Scheme 29. A representative example of oxidative Au catalysis, and the bimetallic mechanism proposed by Toste.

Scheme 30. Hydroalkylation of alkynes developed by Lalic, and proposed binuclear catalytic mechanism.

Scheme 31. Bifunctional catalysis for epoxide carbonylation developed by Coates.

Scheme 32. Bifunctional catalysis for C–H borylation developed by Mankad.

Scheme 33. Pd(i)-catalyzed C–X coupling developed by Schoenebeck.

Scheme 34. Allylic amination-catalysed by a Pd–Ti heterobimetallic complex, and the proposed rate-determining C–N coupling transition state proposed by Michaelis and Ess.

Scheme 35. Dinickel-catalysed alkyne cyclotrimerisation developed by Uyeda, and the proposed bimetallic transition state that steers regioselectivity.

Dominic R. Pye

Neal P. Mankad