10.1002/chem.201701342
Chemistry - A European Journal
FULL PAPER
CPME (3.0 mL) was added to a mixture of RuCl2((S)-dppmp)2 (6d) (71.1
mg, 0.100 mmol), Zn(OCOCF3)2 (58.3 mg, 0.200 mmol), and KHMDS
(39.9 mg, 0.200 mmol) at room temperature. The orange reaction mixture
was stirred at 100 °C for 13 h. All volatiles were removed in vacuo to give
brown solid. The solid was extracted by Et2O (5 mL X 3) and filtered
through the pad of Celite. The filtrate was concentrated to obtain yellow
solid (60 mg, 0.069 mmol, 69% yield). Mp 218 °C (dec.); 1H NMR (400
MHz, benzene-d6, 30 °C), δ 1.33-1.57 (m, 4H, methylene), 1.61-1.82 (m,
4H, methylene), 2.35-2.53 (m, 2H, methylene), 2.61-2.79 (m, 4H,
methylene), 2.79-2.95 (m, 2H, methylene), 3.90 (br s, 2H, methyne), 6.80-
7.08 (m, 16H, Ar), 7.31 (br s, 4H, Ar), 8.40 (br s, 2H, NH); 13C{1H} NMR
(100 MHz, benzene-d6, 30 °C) δ 27.7, 31.47 (d, JC-P = 7.7 Hz), 31.54 (d, JC-
P = 7.7 Hz), 37.4 (d, JC-P = 14 Hz), 37.6 (d, JC-P = 14 Hz), 48,5, 59.8 (d, JC-
P = 2.4 Hz), 59.8 (d, JC-P = 2.4 Hz), 114.3 (q, JC-F = 292 Hz), 129.4, 130.1,
132.5 (d, JC-P = 4.4 Hz), 132.6 (d, JC-P = 4.4 Hz), 133.5 (d, JC-P = 4.9 Hz),
133.6 (d, JC-P = 4.9 Hz), 166.7 (q, JC-F = 36 Hz), two aryl signals were
overlapped with signal of deuterium solvent; 19F{1H} NMR (376 MHz,
benzene-d6, 30 ºC) δ -74.7; 31P{1H} NMR (162 MHz, benzene-d6, 30 ºC) δ
52.5; IR (KBr, /cm-1) 3443, 3179, 3059, 2963, 1686, 1670, 1486, 1435,
1415, 1261, 1198, 1137, 1099, 1026, 839, 803, 788, 741, 727, 696, 527,
513; MS (FAB) m/z 866 (M+); HRMS (FAB) m/z calcd. for
C38H40F6N2O4P2Ru 866.1411 found 866.1404; Anal. Calcd for
C38H40F6N2O4P2Ru: C, 52.72; H, 4.66; N, 3.24. Found: C, 52.56; H, 4.95;
N, 2.89.
Experimental Section
General Information
All manipulations involving air- and moisture-sensitive compounds were
carried out under an argon atmosphere by using standard vacuum line and
Schlenk tube techniques. All liquid alcohols and amines were distilled
under an argon atmosphere from the calcium hydride. Alternatively,
toluene, THF, Et2O and hexane were dried and deoxygenated by using
Grubbs column (Glass Counter Solvent Dispending System, Nikko
Hansen & Co, Ltd.). 1,4-Dioxane was distilled over sodium benzophenone
ketyl under an argon atmosphere. Amide substrates were synthesized by
standard condensation reaction of acyl chlorides and amines. All other
reagents were purchased at the highest commercial quality and used
without further purification. Flash column chromatography was performed
using silica gel 60 (0.040–0.063 mm, 230–400 mesh ASTM).
Physical Measurements
1H NMR (400 MHz), 13C{1H} NMR (100 MHz), 19F{1H} NMR (376 MHz) and
31P{1H} NMR (160 MHz) spectra were measured on Bruker Avance III-400
spectrometers in 5 mm NMR tubes. All 1H NMR chemical shifts were
reported in ppm relative to the residual solvent protons in chloroform-d1 at
δ 7.26, benzene-d6 at δ 7.16, dichloromethane-d2 at δ 5.32, and DMSO-d6
at δ 2.50. All 13C{1H} NMR chemical shifts were reported in ppm relative
to carbon resonance of the solvent itself in chloroform-d1 at δ 77.16,
benzene-d6 at δ 128.06, dichloromethane-d2 at δ 53.84, and DMSO- d6 at
δ 39.52. All 19F{1H} NMR chemical shifts were reported in ppm relative to
an external reference of α,α,α-trifluorotoluene at δ -63.9. 31P{1H} NMR
chemical shifts were recorded in ppm relative to 85% H3PO4 as an external
standard at δ 0.00. GC analyses were recorded on a Shimadzu GC-2014
gas chromatograph with J&W Scientific DB-5 column. High-resolution
mass spectrometry (HRMS) was performed on a JEOL JMS-700 (EI, FAB
plus) and a Brucker Daltonics MicroTOF (ESI plus). IR spectra were
recorded on a JASCO FT/IR-230 spectrometer. X-ray crystallographic
studies were performed on Rigaku XtaLAB P200 system with graphite-
monochromated Mo Kα radiation (λ = 0.71075). All melting point were
recorded on BUCHI melting point M-565. Elemental analyses were
recorded by using Perkin-Elmer 2400 at the Faculty of Engineering
Science, Osaka University.
Acknowledgements
T.H. and A.I. acknowledge financial support from a JSPS
Research Fellowship for Young Scientists and the JSPS
Japanese-German Graduate Externship Program. This work was
supported by JSPS KAKENHI Grant Number JP15H057950, a
Grant-in-Aid for Scientific Research on Innovative Areas, and
JP262480280, a Grant-in-Aid for Scientific Research(A) of The
Ministry of Education, Culture, Sports, Science, and Technology,
Japan. We thank Prof. H. Tsurugi and Dr. Y. Kita for fruitful
discussions.
General Procedures for the Catalytic Dehydrogenative Coupling
Reaction
Keywords: dehydrogenative synthesis • ruthenium • imine •
amide • selectivity
Dehydrogenative synthesis of imine: A mixture of RuCl2(dppea)2 (6a)
= 2-diphenylphosphinoethane; 3.2 mg, 5.0 X
10-3 mmol),
[1]
[2]
J. March, Advanced Organic Chemistry, sixth ed.; Wiley: New York, 1992.
a) M. H. S. A. Hamid, P. A. Slatford, J. M. J. Williams, Adv. Synth. Catal.
2007, 349, 1555. b) G. E. Dobereiner, R. H. Crabtree, Chem. Rev. 2010,
110, 681. c) G. Guillena, D. J. Ramon, M. Yus, Chem. Rev. 2010, 110,
1611. d) C. Gunanathan, D. Milstein, Science 2013, 341, 249. e) C. Chen,
F. Verpoort, Q. Wu, RSC Adv. 2016, 6, 55599. f) Q. Yang, Q. Wang, Z.
Yu, Chem. Soc. Rev. 2015, 44, 2305.
(dppea
Zn(OCOCF3)2 (2.9 mg, 1.0 X 10-2 mmol), KOtBu (22.4 mg, 0.20 mmol),
alcohol (1.5 mmol), and amine (1.0 mmol) in 1,4-dioxane (2.0 mL) was
refluxed for 18 h. After cooling to room temperature, the resulting mixture
was purified by silica gel column chromatography (Hexane:NEt3 = 20:1).
Dehydrogenative synthesis of amide: A mixture of RuCl2((S)-dppmp)2 (6d)
[(S)-dppmp = (S)-2-((diphenylphosphanyl)methyl)-pyrrolidine; 7.1 mg, 1.0
X 10-2 mmol], Zn(OCOCF3)2 (5.8 mg, 2.0 X 10-2 mmol), KHMDS (39.9 mg,
0.200 mmol), alcohol (1.0 mmol), and amine (1.5 mmol) in CPME (2.0 mL)
was refluxed for 18 h. After cooling to room temperature, the resulting
mixture was purified by silica gel column chromatography (Hexane:AcOEt
= 8:1).
[3]
[4]
a) S. Tang, J. Yuan, C. Liu, A. Lei, Dalton Trans. 2014, 43, 13460. b) I.
B. Krylov, V. A. Vil’, A. O. Terent’ev, Beilstein J. Org. Chem. 2015, 11,
92.
a) J. M. Ketcham, I. Shin, T. P. Montgomery, M. J. Krische, Angew.
Chem., Int. Ed. 2014, 53, 9142. b) A.-M. J. Dechert-Schmitt, D. C.
Schmitt, T. Itoh, M. J. Krische, Nat. Prod. Rep. 2014, 31, 504. c) K. D.
Nguyen, B. Y. Park, T. Luong, H. Sato, V. J. Garza, M. J. Krische,
Science 2016, 354, 6310.
Synthetic Procedure of Complexes
[5]
a) B. Gnanaprakasam, J. Zhang, D. Milstein, Angew. Chem., Int. Ed.
2010, 49, 1468. b) J. W. Rigoli, S. A. Moyer, S. D. Pearce, J. M.
Schomaker, Org. Biomol. Chem. 2012, 10, 1746. c) A. Maggi, R. Madsen,
Organometallics 2012, 31, 451. d) B. Saha, S. M. W. Rahaman, P. Daw,
G. Sengupta, J. K. Bera, Chem.—Eur. J. 2014, 20, 6542.
Complexes 6a,19 6b,20 6d,21 6e,22 6f,23 6g,24 and 8a13 were synthesized
according to literature procedures.
Synthesis of Ru(OCOCF3)2((S)-dppmp)2 (8d)
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