Practical aspects and mechanism of asymmetric hydrogenation with chiral half-sandwich complexes

Molecules

Volumn 18, Issue 6, 2013, Pages 6804-6828

  Václavík, Jiří ^a   Šot, Petr ^a   Vilhanová, Beáta ^a   Pecháček, Jan ^a   Kuzma, Marek ^b   Kačer, Petr ^a  

^a INSTITUTE OF CHEMICAL TECHNOLOGY   (Czech Republic)

^b INSTITUTE OF MICROBIOLOGY   (Czech Republic)

Author keywords

Asymmetric hydrogenation; Imine; Mechanism; Reaction conditions; Ruthenium

Indexed keywords

ALKENE; HYDROGEN; IMINE; RUTHENIUM;

CATALYSIS; CHEMISTRY; HYDROGENATION; STEREOISOMERISM; REVIEW;

ALKENES; CATALYSIS; HYDROGEN; HYDROGENATION; IMINES; RUTHENIUM; STEREOISOMERISM;

EID: 84879634412     PISSN: None     EISSN: 14203049     Source Type: Journal    
DOI: 10.3390/molecules18066804     Document Type: Review

References (91)

1. Hashiguchi, S.; Fujii, A.; Takehara, J.; Ikariya, T.; Noyori, R. Asymmetric transfer hydrogenation of aromatic ketones catalyzed by chiral ruthenium(II) complexes. J. Am. Chem. Soc. 1995, 117, 7562-7563.
2. Fujii, A.; Hashiguchi, S.; Uematsu, N.; Ikariya, T.; Noyori, R. Ruthenium(II)-catalyzed asymmetric transfer hydrogenation of ketones using a formic acid-triethylamine mixture. J. Am. Chem. Soc. 1996, 118, 2521-2522.
3. Uematsu, N.; Fujii, A.; Hashiguchi, S.; Ikariya, T.; Noyori, R. Asymmetric transfer hydrogenation of imines. J. Am. Chem. Soc. 1996, 118, 4916-4917.
4. 6- arene/ N-arylsulfonyl-diamine-RuII catalysts in the asymmetric transfer hydrogenation of ketones and imines. Molecules 2011, 16, 5460-5495.
5. Blackmond, D.G.; Ropic, M.; Stefinovic, M. Kinetic studies of the asymmetric transfer hydrogenation of imines with formic acid catalyzed by Rh-diamine catalysts. Org. Proc. Res. Dev. 2006, 10, 457-463.
6. Václavík, J.; Přech, J.; Kuzma, M.; Kačer, P.; Červený, L. In situ monitoring of asymmetric transfer hydrogenation of imines using NMR spectrometry. Chem. Listy 2012, 106, 206-210.
7. Kajita, M.; Niwa, T.; Fujisaki, M.; Ueki, M.; Niimura, K.; Sato, M.; Egami, K.; Naoi, M.; Yoshida, M.; Nagatsu, T. Detection of 1-phenyl-N-methyl-1, 2,3,4-tetrahydroisoquinoline and 1-phenyl-1,2,3,4-tetrahydroisoquinoline in human brain by gas chromatography-tandem mass spectrometry. J. Chromatogr. B 1995, 669, 345-351.
8. Makino, Y.; Tasaki, Y.; Ohta, S.; Hirobe, M. Confirmation of the enantiomers of 1-methyl- 1,2,3,4-tetrahydroisoquinoline in the mouse brain and foods applying gas chromatography/mass spectrometry with negative ion chemical ionization. Biol. Mass Spectrom. 1990, 19, 415-419.
9. Kažoka, H.; Rotkaja O.; Varačeva, L. Enantioseparation of 1-phenyl-1,2,3,4-tetrahydroisoquinoline on polysaccharide-based chiral stationary phases. Chromatographia 2011, 73, 123-129.
10. Lee, A.; Choi, H.J.; Jin K.B.; Hyun, M.H. Liquid chromatographic resolution of 1-aryl-1,2,3,4- tetrahydroisoquinolines on a chiral stationary phase based on (+)-(18-crown-6)-2,3,11,12- tetracarboxylic acid. J. Chromatogr. A 2011, 1218, 4071-4076.
11. Inoue, H.; Matsubara, D.; Tsuruta, Y. Simultaneous analysis of 1,2,3,4-tetrahydroisoquinolines by high-performance liquid chromatography using 4-(5,6-dimethoxy-2-phthalimidinyl)-2- methoxyphenylsulfonyl chloride as a fluorescent labeling reagent. J. Chromatogr. B 2008, 867, 32-36.
12. Song, Y.; Xu, J.; Hamme A.; Liu, Y.-M. Capillary liquid chromatography-tandem mass spectrometry of tetrahydroisoquinoline derived neurotoxins: a study on the blood-brain barrier of rat brain. J. Chromatogr. A 2006, 1103, 229-234.
13. Cai, M.; Liu, Y.-M. Quantification of salsolinol enantiomers by stable isotope dilution liquid chromatography with tandem mass spectrometric detection. Rapid Commun. Mass Spectrom. 2008, 22, 4171-4177.
14. Přech, J.; Matoušek, V.; Václavík, J.; Pecháček, J.; Syslová, K.; Šot, P.; Januščák, J.; Vilhanová, B.; Kuzma, M.; Kačer, P. Determination of enantiomeric composition of substituted tetrahydroisoquinolines based on derivatization with menthyl chloroformate. Am. J. Anal. Chem. 2013, 4, 125-133.
15. Dale, J.A.; Mosher, H.S. Nuclear magnetic resonance enantiomer reagents. Configurational correlations via nuclear magnetic resonance chemical shifts of diastereomeric mandelate, O-methylmandelate, and α-methoxy-α- trifluoromethylphenylacetate (MTPA) Esters. J. Am. Chem. Soc. 1973, 95, 512-519.
16. Pirkle, W.H.; Burlingame, T.G.; Beare, S.D. Optically active NMR solvents VI. The determination of optical purity and absolute configuration of amines. Tetrahedron Lett. 1968, 9, 5849-5852.
17. Vilhanová, B.; Matoušek, V.; Václavík, J.; Syslová, K.; Přech, J.; Pecháček, J.; Šot, P.; Januščák, J.; Toman, J.; Zápal, J.; Kuzma, M.; Kačer, P. Two optimized synthetic pathways toward a chiral precursor of Mivacurium chloride and other skeletal muscle relaxants. Tetrahedron: Asymmetry 2013, 24, 50-55.
18. Pecháček, J.; Václavík, J.; Přech, J.; Šot, P.; Januščák, J.; Vilhanová, B.; Vavřík, J.; Kuzma, M.; Kačer, P. Asymmetric transfer hydrogenation of imines catalyzed by a Noyori-type Ru(II) complex-a parametric study. Tetrahedron: Asymmetry 2013, 24, 233-239.
19. Balcells, D.; Maseras, F. Computational approaches to asymmetric synthesis. New J. Chem. 2007, 31, 333-343.
20. Zhou, X.; Wu, X.; Yang, B.; Xiao, J. Varying the ratio of formic acid to triethylamine impacts on asymmetric transfer hydrogenation of ketones. J. Mol. Catal. A: Chem. 2012, 357, 133-140.
21. Wu, X.; Li, X.; Zanotti-Gerosa, A.; Pettman, A.; Liu, J.; Mills, A. J.; Xiao, J. RhIII- and IrIII-catalyzed asymmetric transfer hydrogenation of ketones in water. Chem. Eur. J. 2008, 14, 2209-2222.
22. Zhang, J.; Blazecka, P.G.; Bruendl, M.M.; Huang, Y. Ru-TsDPEN with formic acid/Hünig's base for asymmetric transfer hydrogenation, a practical synthesis of optically enriched N-propyl pantolactam. J. Org. Chem. 2009, 74, 1411-1414.
23. Kuzma, M.; Václavík, J.; Novák, P.; Přech, J.; Januščák, J.; Červený, J.; Pecháček, J.; Šot, P.; Vilhanová, B.; Matoušek, V.; Goncharova, I.I.; Urbanová, M.; Kačer, P. New insight into the role of a base in the mechanism of imine transfer hydrogenation on a Ru(II) half-sandwich complex. Dalton Trans. 2013, 42, 5174-5182.
24. 6-arene-ruthenium(II) complexes. Angew. Chem. Int. Ed. 2001, 40, 2818-2821.
25. Takehara, J.; Hashiguchi, S.; Fujii, A.; Inoue, S.; Ikariya, T.; Noyori, R. Amino alcohol effects on the ruthenium (II)-catalysed asymmetric transfer hydrogenation of ketones in propan-2-ol. Chem. Commun. 1996, 233-234.
26. Yamada, I.; Noyori, R. Asymmetric transfer hydrogenation of benzaldehydes. Org. Lett. 2000, 2, 3425-3427.
27. Vedejs, E.; Trapencieris, P.; Suna, E. Substituted isoquinolines by Noyori transfer hydrogenation: enantioselective synthesis of chiral diamines containing an aniline subunit. J. Org. Chem. 1999, 64, 6724-6729.
28. Samano, V.; Ray, J.A.; Thompson, J.B.; Mook, R.A.; Jung, D.K.; Koble, C.S.; Martin, M.T.; Bigham, E.C.; Regitz, C.S.; Feldman, P.L.; Boros, E.E. Synthesis of ultra-short-acting neuromuscular blocker GW 0430: A remarkably stereo- and regioselective tetrahydroisoquinolinium. Org. Lett. 1999, 1, 1993-1996.
29. Ohkuma, T.; Utsumi, N.; Watanabe, M.; Tsutsumi, K.; Arai, N.; Murata, K. Asymmetric hydrogenation of α-hydroxy ketones catalyzed by MsDPEN-Cp*Ir(III) complex. Org. Lett. 2007, 9, 2565-2567.
30. Shirai, S.; Nara, H.; Kayaki, Y.; Ikariya, T. Remarkable positive effect of silver salts on asymmetric hydrogenation of acyclic imines with Cp*Ir complexes bearing chiral N-sulfonylated diamine ligands. Organometallics 2009, 28, 802-809.
31. Chen, F.; Wang, T.; He, Y.; Ding, Z.; Li, Z.; Xu, L.; Fan, Q.-H. Asymmetric hydrogenation of N-alkyl ketimines with phosphine-free, chiral, cationic Ru-MsDPEN catalysts. Chem. Eur. J. 2011, 17, 1109-1113.
32. Ariger, M.A.; Carreira, E.M. pH-Independent transfer hydrogenation in water: Catalytic, enantioselective reduction of β-keto esters. Org. Lett. 2012, 14, 4522-4524.
33. Yin, L.; Zheng, Y.; Jia, X.; Li, X.; Chan, A. S. C. Efficient and promising asymmetric preparation of enantiopure tolvaptan via transfer hydrogenation with robust catalysts. Tetrahedron: Asymmetry 2010, 21, 2390-2393.
34. Přech, J.; Václavík, J.; Šot, P.; Pecháček, J.; Vilhanová, B.; Januščák, J.; Syslová, K.; Pažout, R.; Maixner, J.; Zápal, J.; Kuzma, M.; Kačer, P. Asymmetric transfer hydrogenation of 1-phenyl dihydroisoquinolines using Ru(II) diamine catalysts. Catal. Commun. 2013, 36, 67-70.
35. Li, X.; Blacker, J.; Houson, I.; Wu, X.; Xiao, J. An efficient Ir(III) catalyst for the asymmetric transfer hydrogenation of ketones in neat water. Synlett 2006, 2006, 1155-1160.
36. Lu, C.; Luo, Z.; Huang, L.; Li, X. The Ru-catalyzed enantioselective preparation of chiral halohydrins and their application in the synthesis of (R)-clorprenaline and (S)-sotalol. Tetrahedron: Asymmetry 2011, 22, 722-727.
37. Luo, Z.; Qin, F.; Yan, S.; Li, X. An efficient and promising method to prepare Ladostigil (TV3326) via asymmetric transfer hydrogenation catalyzed by Ru-Cs-DPEN in an HCOONa-H2O-surfactant system. Tetrahedron: Asymmetry 2012, 23, 333-338.
38. Crépy, K.V.L.; Imamoto, T. Recent developments in catalytic asymmetric hydrogenation. Adv. Synth. Catal. 2003, 345, 79-101.
39. Majdloch, R.; Januščák, J.; Kuzma, M.; Kačer, P. Institute of Chemical Technology in Prague. Manuscript in Preparation
40. Martins, J.E.D.; Clarkson, G.J.; Wills, M. Ru(II) complexes of N-alkylated TsDPEN ligands in asymmetric transfer hydrogenation of ketones and imines. Org. Lett. 2009, 11, 847-850.
41. Martins, J.E.D.; Contreras Redondo, M.A.; Wills, M. Applications of N'-alkylated derivatives of TsDPEN in the asymmetric transfer hydrogenation of CO and CN bonds. Tetrahedron: Asymmetry 2010, 21, 2258-2264.
42. Manville, C.V.; Docherty, G.; Padda, R.; Wills, M. Application of proline-functionalised 1,2-diphenylethane-1,2-diamine (DPEN) in asymmetric transfer hydrogenation of ketones. Eur. J. Org. Chem. 2011, 2011, 6893-6901.
43. Johnson, T.C.; Totty, W.G.; Wills, M. Application of ruthenium complexes of triazole-containing tridentate ligands to asymmetric transfer hydrogenation of ketones. Org. Lett. 2012, 14, 5230-5233.
44. Hannedouche, J.; Clarkson, G.J.; Wills, M. A new class of "tethered" ruthenium(II) catalyst for asymmetric transfer hydrogenation reactions. J. Am. Chem. Soc. 2004, 126, 986-987.
45. Hayes, A.M.; Morris, D.J.; Clarkson, G.J.; Wills, M. A class of ruthenium(II) catalyst for asymmetric transfer hydrogenations of ketones. J. Am. Chem. Soc. 2005, 127, 7318-7319.
46. Kei, F.; Cheung, K.; Hayes, A.M.; Hannedouche, J.; Yim, A.S.Y.; Wills, M. "Tethered" Ru(II) catalysts for asymmetric transfer hydrogenation of ketones. J. Org. Chem. 2005, 70, 3188-3197.
47. Morris, D.J.; Hayes, A.M.; Wills, M. The "reverse-tethered" ruthenium (II) catalyst for asymmetric transfer hydrogenation: further applications. J. Org. Chem. 2006, 71, 7035-7044.
48. Cheung, F.K.; Lin, C.; Minissi, F.; Crivillé, A.L.; Graham, M.A.; Fox, D.J.; Wills, M. An investigation into the tether length and substitution pattern of arene-substituted complexes for asymmetric transfer hydrogenation of ketones. Org. Lett. 2007, 9, 4659-4662.
49. Matharu, D. S.; Martins, J. E. D.; Wills, M. Asymmetric transfer hydrogenation of C=O and C=N bonds by tethered Rh(III) catalysts. Chem. Asian J. 2008, 3, 1374-1383.
50. Cheung, F.K.K.; Clarke, A.J.; Clarkson, G.J.; Fox, D.J.; Graham, M.A.; Lin, C.; Crivillé, A.L.; Wills, M. Kinetic and structural studies on "tethered" Ru(II) arene ketone reduction catalysts. Dalton Trans. 2010, 39, 1395-1402.
51. Soni, R.; Cheung, F.K.; Clarkson, G.C.; Martins, J.E.D.; Graham, M.A.; Wills, M. The importance of the N-H bond in Ru/TsDPEN complexes for asymmetric transfer hydrogenation of ketones and imines. Org. Biomol. Chem. 2011, 9, 3290-3294.
52. Kačer, P.; Kuzma, M.; Leitmannová, E.; Č ervený, L. Ruthenium complexes for asymmetric transfer hydrogenation. In Organometallic Compounds: Preparation, Structure and Properties; Chin, H.F., Ed.; Nova Science Publishers, Inc.: Hauppauge, NY, USA, 2010; pp. 373-401.
53. Touge, T.; Hakamata, T.; Hideki, N.; Kobayashi, T.; Sayo, N.; Saito, T.; Kayaki, Y.; Ikariya, T. Oxo-tethered ruthenium(II) complex as a bifunctional catalyst for asymmetric transfer hydrogenation and H2 hydrogenation. J. Am. Chem. Soc. 2011, 133, 14960-14963.
54. Parekh, V.; Ramsden, A.; Wills, M. Ether-tethered Ru(II)/TsDPEN complexes; synthesis and applications to asymmetric transfer hydrogenation. Catal. Sci. Technol. 2012, 2, 406-414.
55. 6-arene/N-tosylethylenediamine-ruthenium (II) complexes: Solution behavior and catalytic activity for asymmetric hydrogenation. Chem. Asian J. 2010, 5, 806-816.
56. Ito, M.; Endo, Y.; Ikariya, T. Well-defined triflylamide-tethered arene-Ru(Tsdpen) complexes for catalytic asymmetric hydrogenation of ketones. Organometallics 2008, 27, 6053-6055.
57. Ito, M.; Endo, Y.; Tejima, N.; Ikariya, T. Bifunctional triflylamide-tethered Cp'Rh and Cp'Ir complexes: A new entry for asymmetric hydrogenation catalysts. Organometallics 2010, 29, 2397-2399.
58. Mao, J.; Baker, D. C. A chiral rhodium complex for rapid asymmetric transfer hydrogenation of imines with high enantioselectivity. Org. Lett. 1999, 1, 841-843.
59. Wu, J.; Wang, F.; Ma, Y.; Cui, X.; Cun, L.; Zhu, J.; Deng, J.; Yu, B. Asymmetric transfer hydrogenation of imines and iminiums catalyzed by a water-soluble catalyst in water. Chem. Commun. 2006, volume, 1766-1768.
60. Evanno, L.; Ormala, J.; Pihko, P.M. A highly enantioselective access to tetrahydroisoquinoline and β-carboline alkaloids with simple Noyori-type catalysts in aqueous media. Chem. Eur. J. 2009, 15, 12963-12967.
61. Chang, M.; Li, W.; Zhang, X. A highly efficient and enantioselective access to tetrahydroisoquinoline alkaloids: asymmetric hydrogenation with an iridium catalyst. Angew. Chem. Int. Ed. 2011, 50, 10679-10681.
62. 6-p-cymene) TsDPEN]. Catal. Lett. 2013, 143, 555-562.
63. Dub, P. A.; Ikariya, T. Quantum chemical calculations with the inclusion of nonspecific and specific solvation: Asymmetric transfer hydrogenation with bifunctional ruthenium catalysts. J. Am. Chem. Soc. 2013, 135, 2604-2619.
64. Koike, T.; Ikariya, T. Mechanistic aspects of formation of chiral ruthenium hydride complexes from 16-electron ruthenium amide complexes and formic acid: Facile reversible decarboxylation and carboxylation. Adv. Synth. Catal. 2004, 346, 37-41.
65. 6)Ru complexes. Organometallics 2002, 21, 2964-2969.
66. Aliende, C.; Pérez-Manrique, M.; Jalón, F.A.; Manzano, B.R.; Rodíguez, A.M.; Espino, G. Arene ruthenium complexes as versatile catalysts in water in both transfer hydrogenation of ketones and oxidation of alcohols. Selective deuterium labeling of rac-1-phenylethanol. Organometallics 2012, 31, 6106-6123.
67. 2 to formate by water-stable iridium dihydride pincer complex. Dalton Trans. 2013, 42, 5755-5763.
68. Soldevila-Barreda, J.J.; Bruijnincx, P.C.A.; Habtemariam, A.; Clarkson, G.J.; Deeth, R.J.; Sadler, P.J. Improved catalytic activity of ruthenium-arene complexes in the reduction of NAD+. Organometallics 2012, 31, 5958-5967.
69. Letko, C.S.; Heiden, Z.M.; Rauchfuss, T.B.; Wilson, S.R. Coordination chemistry of the soft chiral Lewis acid [Cp*Ir(TsDPEN)]+. Inorg. Chem. 2011, 50, 5558-5566.
70. Jolley, K.E.; Zanotti-Gerosa, A.; Hancock, F.; Dyke, A.; Grainger, D.M.; Medlock, J.A.; Nedden, H.G.; Le Paih, J.J.M.; Roseblade, S.J.; Seger, A.; et al. Application of tethered ruthenium catalysts to asymmetric hydrogenation of ketones, and the selective hydrogenation of aldehydes. Adv. Synth. Catal. 2012, 354, 2545-2555.
71. Noyori, R.; Hashiguchi, S. Asymmetric transfer hydrogenation catalyzed by chiral ruthenium complexes. Acc. Chem. Res. 1997, 30, 97-102.
72. Åberg, J.B.; Samec, J.S.M.; Bäckvall, J.-E. Mechanistic investigation on the hydrogenation of imines by [p-(Me2CH)C6H4Me] RuH(NH2CHPhCHPhNSO2C6H4-p-CH3). Experimental support for an ionic pathway. Chem. Commun. 2006, 2771-2773.
73. 6-p-cymene)[(S,S)-N-TsDPEN] as a catalyst: A computational study. Organometallics 2011, 30, 4822-4829.
74. 6-(pcymene)]: A DFT study. Organometallics 2012, 31, 6496-6499.
75. Xue, D.; Chen, Y.-C.; Cui, X.; Wang, Q.-W.; Zhu, J.; Deng, J.-G. Transfer hydrogenation of activated C=C bonds catalyzed by ruthenium amido complexes: Reaction scope, limitation, and enantioselectivity. J. Org. Chem. 2005, 70, 3584-3591.
76. Tang, W.; Zhang, X. New chiral phosphorus ligands for enantioselective hydrogenation. Chem. Rev. 2003, 103, 3029-3069.
77. Václavík, J.; Kačer, P.; Červený, L. Rational design of chiral ruthenium complexes for asymmetric hydrogenations. In Homogeneous Catalysts: Types, Reactions and Applications; Poehler, A.C., Ed.; Nova Science Publishers, Inc.: Hauppauge, NY, USA, 2011; pp. 127-153.
78. Lühr, S.; Holz, J.; Börner, A. The synthesis of chiral phosphorus ligands for use in homogeneous metal catalysis. ChemCatChem 2011, 3, 1708-1730.
79. 6-arene/N-tosylethylenediamine- ruthenium(II) catalysts. J. Am. Chem. Soc. 2006, 128, 8724-8725.
80. 6-arene-N-tosylethylenediamineruthenium( II) complexes. Chem. Asian J. 2006, 1, 102-110.
81. 6-arene/N- tosylethylenediamine ruthenium (II). Organometallics 2009, 28, 2078-2084.
82. 6-arene/TsDPEN-ruthenium(II) complexes. Org. Lett. 2007, 9, 255-257.
83. Ohkuma, T.; Utsumi, N.; Watanabe, M.; Tsutsumi, K.; Arai, N.; Murata, K. Asymmetric hydrogenation of α-hydroxy aromatic ketones catalyzed by MsDPEN-Cp*Ir(III) Complex. Org. Lett. 2007, 13, 2565-2567.
84. Li, C.; Xiao, J. Asymmetric hydrogenation of cyclic imines with an ionic Cp*Rh(III) catalyst. J. Am. Chem. Soc. 2008, 130, 13208-13209.
85. Chen, F.; Ding, Z.; He, Y.; Qin, J.; Wang, T.; Fan, Q.-H. Asymmetric hydrogenation of N-alkyl and N-aryl ketimines using chiral cationic Ru(diamine) complexes as catalysts: The counteranion and solvent effects, And substrate scope. Tetrahedron 2012, 68, 5248-5257.
86. Chen, F.; Ding, Z.; Qin, J.; Wang, T.; He, Y.; Fan, Q. Highly effective asymmetric hydrogenation of cyclic N-alkyl imines with chiral cationic Ru-MsDPEN catalysts. Org. Lett. 2011, 13, 4348-4351.
87. Kaldor, I.; Feldman, P.L.; Mook, R.A.; Ray, J.A.; Samano, V.; Sefler, A.M.; Thompson, J.B.; Travis, B.R.; Boros, E.E. Stereocontrolled synthesis of cis-dibenzoquinolizine chlorofumarates: curare-like agents of ultrashort duration. J. Org. Chem. 2001, 66, 3495-3501.
88. Boros, E.E.; Samano, V.; Ray, J.A.; Thompson, J.B.; Jung, D.K.; Kaldor, I.; Koble, C.S.; Martin, M.T.; Styles, V.L.; Mook, R.A.; et al. Neuromuscular blocking activity and therapeutic potential of mixed-tetrahydroisoquinolinium halofumarates and halosuccinates in rhesus monkeys. J. Med. Chem. 2003, 46, 2502-2515.
89. Li, Y.; Li, Z.; Li, F.; Wang, Q.; Tao, F. Preparation of polymer-supported Ru-TsDPEN catalysts and use for enantioselective synthesis of (S)-fluoxetine. Org. Biomol. Chem. 2005, 3, 2513-2518.
90. Liu, J.; Zhou, D.; Jia, X.; Huang, L.; Li, X.; Chan, A.S.C. A convenient synthesis of (R)-salmeterol via Rh-catalyzed asymmetric transfer hydrogenation. Tetrahedron: Asymmetry 2008, 19, 1824-1828.
91. Huang, L.; Liu, J.; Shan, W.; Liu, B. A. O.; Shi, A.; Li, X. The asymmetric synthesis of (R,R)-formoterol via transfer hydrogenation with polyethylene glycol bound Rh catalyst in PEG2000 and water. Chirality 2010, 211, 206-211. Metabolomics