Catalysis with cycloruthenated complexes

Abstract

Cycloruthenated complexes have been studied extensively over the last few decades. Many accounts of their synthesis, characterisation, and catalytic activity in a wide variety of transformations have been reported to date. Compared with their non-cyclometallated analogues, cycloruthenated complexes may display enhanced catalytic activities in known transformations or possess entirely new reactivity. In other instances, these complexes can be chiral, and capable of catalysing stereoselective reactions. In this review, we aim to highlight the catalytic applications of cycloruthenated complexes in organic synthesis, emphasising the recent advancements in this field.

Scheme 1. Room-temperature C–H/olefin coupling reported by Murai.

Scheme 2. Selectivity switch with a cyclometallated ruthenium catalyst for C–H alkylation using secondary alkyl halides. DG = directing group.

Scheme 3. Larrosa's late-stage ortho-alkylation of N-directing group-containing arenes procedure using primary alkyl halides.

Scheme 4. Mechanism of C–H functionalisation of N-directing group-containing arenes with primary and secondary alkyl bromides by Larrosa.

Scheme 5. Commonly postulated mechanism for C–H arylation of N-directing group arenes with ruthenium.

Scheme 6. Synthesis of cyclometallated complex Ru12 and use as catalyst.

Scheme 7. Larrosa's ortho-arylation procedure. DG = N-directing group.

Scheme 8. Frost's meta-sulfonation procedure.

Scheme 9. meta-Nitration (top) and meta-acylation (bottom) via bis-cyclometallated species Ru20.

Scheme 10. C–H activation and annulation using a cycloruthenated complex.

Scheme 11. Ackermann's electrocatalysed C–H activation/annulation cascade proceeding through 7-membered ruthenacycle intermediates.

Scheme 12. First use of a chiral-at-ruthenium complex in asymmetric catalysis.

Scheme 13. Enantioselective alkynylation of trifluoromethyl ketones catalysed by chiral-at-ruthenium complexes.

Scheme 14. Ru catalysed intramolecular C(sp³)–H amination of azidoacetamides (A) and proposed mechanism of the reaction (B).

Scheme 15. Intramolecular C(sp³)–H amination of alkylazides.

Scheme 16. Asymmetric intramolecular C(sp³)–H amination and oxygenation (A) and proposed reaction pathways (B).

Scheme 17. C–H amination of urea derivatives.

Scheme 18. C₂-symmetric and non-C₂-symmetric new complexes (A) and C(sp³)–H amidation of 1,4,2-dioxazol-5-ones (B).

Scheme 19. C–H amination of urea derivative catalysed by normal and abnormal NHC coordination complexes.

Scheme 20. First cycloruthenated complex in Z-selective olefin metathesis.

Scheme 21. Z-selective olefin metathesis of different alkenes using Ru41 as catalyst.

Scheme 22. New cycloruthenated NHC complexes for cross metathesis reactions.

Scheme 23. Homodimerisation of allylbenzene with new cycloruthenated catalysts.

Scheme 24. Homodimerisation of challenging olefins with new ruthenium catalysts.

Scheme 25. Alkene scope with nitrato-based catalyst Ru50.

Scheme 26. Cross metathesis with allylbenzene and bis-acetate olefin.

Scheme 27. Z-selective metathesis for macrocyclisation.

Scheme 28. Asymmetric ring-opening/cross metathesis.

Scheme 29. Enantioselective olefin metathesis with cyclometallated ruthenium complexes.

Scheme 30. Z-selective α,β-unsaturated acetal synthesis and tandem cross metathesis-hydroxylation.

Scheme 31. Selected example of cross metathesis polypeptides.

Scheme 32. First reported pincer catalysed transfer hydrogenation.

Scheme 33. Baratta's transfer hydrogenation of ketones.

Scheme 34. Benzo[h]quinoline pincer catalyst in transfer hydrogenation.

Scheme 35. Chiral ruthenium pincer complex for asymmetric transfer hydrogenation.

Scheme 36. ONC pincer complex in transfer hydrogenation.

Scheme 37. Proposed mechanism with cyclometallated ruthenium pincer complex.

Scheme 38. Improved transfer hydrogenation conditions.

Scheme 39. Transfer hydrogenation of aldehydes.

Scheme 40. Transfer hydrogenation by orthometallated Ru–NHC complexes.

Scheme 41. Effect of ancillary ligand in transfer hydrogenation of unsaturated compounds.

Scheme 42. Proposed mechanism for cyclometalated complex.

Scheme 43. Alkylation of amine with Baratta's catalyst Ru56.

Scheme 44. Beller's alkylation of a primary amine with alcohols catalysed by a cycloruthenated phenylimidazoline complex.

Scheme 45. Proposed mechanism for N-alkylation of amines with alcohols.

Scheme 46. General mechanism for metal-catalysed enantioselective cyclopropanation through diazo decomposition.

Scheme 47. Nishiyama's Ru–Phebox complexes for enantioselective cyclopropanation of alkenes.

Scheme 48. PSCC applied to enantioselective cyclopropanation.

Scheme 49. Enantioselective cyclopropanation of styrenes with succinimidyl diazoacetates catalysed by a homogeneous catalyst Ru86.

Scheme 50. ADA and MDA as carbene precursors applied to the synthesis of an HIV-1 non-nucleoside reverse transcriptase inhibitor.

Scheme 51. Enantioselective cyclopropanation with Ru87 and subsequent product derivatisation.

Scheme 52. Guo's enantioselective cyclopropanation of pyrimidine nucleoside analogues.

Scheme 53. Ruthenium alkenyl oxazoline complexes for enantioselective cyclopropanation.

Scheme 54. Redox-active carbenes in enantioselective cyclopropanation.

Scheme 55. Stereoselective functionalisation of redox-active cyclopropanes A or B.

Scheme 56. Oxidative cyclisation of unsaturated molecules with ruthenium catalysts.

Scheme 57. Itoh's ruthenium-catalysed intramolecular cyclotrimerisation of diynes and triynes and possible biscarbene intermediate.

Scheme 58. Nishiyama's ruthenium-catalysed transfer oxygenative [2 + 2 + 1] cycloaddition.

Scheme 59. Sulfur atom transfer catalytic [2 + 2 + 1] cycloaddition for the synthesis of thiophenes.

Scheme 60. Krische's transfer hydrogenative cycloaddition.

Scheme 61. Linear codimerisation of alkenes by ruthenacyclopentane complexes.

Scheme 62. Ru-catalyzed synthesis of potassium acrylate via oxidative cyclisation.

Scheme 63. Bis-cyclometallated ruthenium complexes for alkyne–alkene coupling.

Michael T. Findlay

Pablo Domingo-Legarda

Gillian McArthur

Andy Yen

Igor Larrosa