41. Kerr WJ, Knox GJ, Paterson LC (2020) Recent advances in iridium(I) catalysis towards
directed hydrogen isotope exchange. J Label Compd Radiopharm 63:281–295. https://doi.
org/10.1002/jlcr.3812
42. Valero M, Kruissink T, Blass J et al (2020) CÀH functionalization – prediction of selectivity
in iridium(I)-catalyzed hydrogen isotope exchange competition reactions. Angew Chem Int Ed
59:5626–5631. https://doi.org/10.1002/anie.201914220
43. Crabtree RH, Felkin H, Morris GE (1977) Cationic iridium diolefin complexes as alkene
hydrogenation catalysts and the isolation of some related hydrido complexes. J Organomet
Chem 141:205–215. https://doi.org/10.1016/S0022-328X(00)92273-3
44. Zhu Y, Fan Y, Burgess K (2010) Carbene-metal hydrides can be much less acidic than
phosphine-metal hydrides: significance in hydrogenations. J Am Chem Soc 132:6249–6253.
https://doi.org/10.1021/ja101233g
45. Dobereiner G, Nova A (2011) Iridium-catalyzed hydrogenation of N-heterocyclic compounds
under mild conditions by an outer-sphere pathway. J Am Chem Soc 133(19):7547–7562.
https://doi.org/10.1021/ja2014983
46. Bennie LS, Fraser CJ, Irvine S et al (2011) Highly active iridium(I) complexes for the selective
hydrogenation of carbon-carbon multiple bonds. Chem Commun 47:11653–11655. https://
doi.org/10.1039/c1cc14367k
47. Semeniuchenko V, Exner TE, Khilya V, Groth U (2011) Homogeneous hydrogenation of
electron-deficient alkenes by iridium complexes. Appl Organomet Chem 25:804–809. https://
doi.org/10.1002/aoc.1841
48. Hopmann KH, Bayer A (2011) On the mechanism of iridium-catalyzed asymmetric hydrogenation of imines and alkenes: a theoretical study. Organometallics 30:2483–2497. https://doi.
org/10.1021/om1009507
49. Woodmansee DH, Pfaltz A (2011) Asymmetric hydrogenation of alkenes lacking coordinating
groups. Chem Commun (Camb) 47:7912–7916. https://doi.org/10.1039/c1cc11430a
50. Maurer F, Huch V, Ullrich A, Kazmaier U (2012) Development of catalysts for the
stereoselective hydrogenation of α,β-unsaturated ketones. J Org Chem 77:5139–5143.
https://doi.org/10.1021/jo300246c
51. Bert K, Noël T, Kimpe W et al (2012) Chiral imidate-ferrocenylphosphanes: synthesis and
application as P,N-ligands in iridium(I)-catalyzed hydrogenation of unfunctionalized and
poorly functionalized olefins. Org Biomol Chem 10:8539–8550. https://doi.org/10.1039/
c2ob25871d
52. Song S, Zhu S-F, Yang S et al (2012) Enantioselective iridium-catalyzed hydrogenation of
β,γ-unsaturated carboxylic acids: an efficient approach to chiral 4-alkyl-4-aryl butanoic acids.
Angew Chem Int Ed 51:2708–2711. https://doi.org/10.1002/anie.201107802
53. Song S, Zhu S, Li Y, Zhou Q-L (2013) Iridium-catalyzed enantioselective hydrogenation of
α,β-unsaturated carboxylic acids with tetrasubstituted olefins. Org Lett 15:3722–3725. https://
doi.org/10.1021/ol401593a
54. Crabtree RH (1979) Iridium compounds in catalysis. Acc Chem Res 12:331
55. Song S, Zhu S-F, Yu Y-B, Zhou Q-L (2013) Carboxy-directed asymmetric hydrogenation of
1,1-diarylethenes and 1,1-dialkylethenes. Angew Chem Int Ed 125:1596–1599. https://doi.
org/10.1002/ange.201208606
56. Kolychev EL, Kronig S, Brandhorst K et al (2013) Iridium(I) complexes with anionic
N-heterocyclic carbene ligands as catalysts for the hydrogenation of alkenes in nonpolar
media. J Am Chem Soc 135:12448–12459. https://doi.org/10.1021/ja406529c
57. Gruber S, Neuburger M, Pfaltz A (2013) Characterization and reactivity studies of dinuclear
iridium hydride complexes prepared from iridium catalysts with N, P and C, N ligands under
hydrogenation. Organometallics 32:4702–4711. https://doi.org/10.1021/om4007467
58. Horváth H, Kathó Á, Udvardy A et al (2014) New water-soluble iridium(I)–N-heterocyclic
carbene–tertiary phosphine mixed-ligand complexes as catalysts of hydrogenation and redox
isomerization. Organometallics 33:6330–6340. https://doi.org/10.1021/om5006148
296
M. Reid
directed hydrogen isotope exchange. J Label Compd Radiopharm 63:281–295. https://doi.
org/10.1002/jlcr.3812
42. Valero M, Kruissink T, Blass J et al (2020) CÀH functionalization – prediction of selectivity
in iridium(I)-catalyzed hydrogen isotope exchange competition reactions. Angew Chem Int Ed
59:5626–5631. https://doi.org/10.1002/anie.201914220
43. Crabtree RH, Felkin H, Morris GE (1977) Cationic iridium diolefin complexes as alkene
hydrogenation catalysts and the isolation of some related hydrido complexes. J Organomet
Chem 141:205–215. https://doi.org/10.1016/S0022-328X(00)92273-3
44. Zhu Y, Fan Y, Burgess K (2010) Carbene-metal hydrides can be much less acidic than
phosphine-metal hydrides: significance in hydrogenations. J Am Chem Soc 132:6249–6253.
https://doi.org/10.1021/ja101233g
45. Dobereiner G, Nova A (2011) Iridium-catalyzed hydrogenation of N-heterocyclic compounds
under mild conditions by an outer-sphere pathway. J Am Chem Soc 133(19):7547–7562.
https://doi.org/10.1021/ja2014983
46. Bennie LS, Fraser CJ, Irvine S et al (2011) Highly active iridium(I) complexes for the selective
hydrogenation of carbon-carbon multiple bonds. Chem Commun 47:11653–11655. https://
doi.org/10.1039/c1cc14367k
47. Semeniuchenko V, Exner TE, Khilya V, Groth U (2011) Homogeneous hydrogenation of
electron-deficient alkenes by iridium complexes. Appl Organomet Chem 25:804–809. https://
doi.org/10.1002/aoc.1841
48. Hopmann KH, Bayer A (2011) On the mechanism of iridium-catalyzed asymmetric hydrogenation of imines and alkenes: a theoretical study. Organometallics 30:2483–2497. https://doi.
org/10.1021/om1009507
49. Woodmansee DH, Pfaltz A (2011) Asymmetric hydrogenation of alkenes lacking coordinating
groups. Chem Commun (Camb) 47:7912–7916. https://doi.org/10.1039/c1cc11430a
50. Maurer F, Huch V, Ullrich A, Kazmaier U (2012) Development of catalysts for the
stereoselective hydrogenation of α,β-unsaturated ketones. J Org Chem 77:5139–5143.
https://doi.org/10.1021/jo300246c
51. Bert K, Noël T, Kimpe W et al (2012) Chiral imidate-ferrocenylphosphanes: synthesis and
application as P,N-ligands in iridium(I)-catalyzed hydrogenation of unfunctionalized and
poorly functionalized olefins. Org Biomol Chem 10:8539–8550. https://doi.org/10.1039/
c2ob25871d
52. Song S, Zhu S-F, Yang S et al (2012) Enantioselective iridium-catalyzed hydrogenation of
β,γ-unsaturated carboxylic acids: an efficient approach to chiral 4-alkyl-4-aryl butanoic acids.
Angew Chem Int Ed 51:2708–2711. https://doi.org/10.1002/anie.201107802
53. Song S, Zhu S, Li Y, Zhou Q-L (2013) Iridium-catalyzed enantioselective hydrogenation of
α,β-unsaturated carboxylic acids with tetrasubstituted olefins. Org Lett 15:3722–3725. https://
doi.org/10.1021/ol401593a
54. Crabtree RH (1979) Iridium compounds in catalysis. Acc Chem Res 12:331
55. Song S, Zhu S-F, Yu Y-B, Zhou Q-L (2013) Carboxy-directed asymmetric hydrogenation of
1,1-diarylethenes and 1,1-dialkylethenes. Angew Chem Int Ed 125:1596–1599. https://doi.
org/10.1002/ange.201208606
56. Kolychev EL, Kronig S, Brandhorst K et al (2013) Iridium(I) complexes with anionic
N-heterocyclic carbene ligands as catalysts for the hydrogenation of alkenes in nonpolar
media. J Am Chem Soc 135:12448–12459. https://doi.org/10.1021/ja406529c
57. Gruber S, Neuburger M, Pfaltz A (2013) Characterization and reactivity studies of dinuclear
iridium hydride complexes prepared from iridium catalysts with N, P and C, N ligands under
hydrogenation. Organometallics 32:4702–4711. https://doi.org/10.1021/om4007467
58. Horváth H, Kathó Á, Udvardy A et al (2014) New water-soluble iridium(I)–N-heterocyclic
carbene–tertiary phosphine mixed-ligand complexes as catalysts of hydrogenation and redox
isomerization. Organometallics 33:6330–6340. https://doi.org/10.1021/om5006148
296
M. Reid