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Synthesis, structure, and properties of [4-methyl-2,6-bis(2methylphenyl)phenyl] bis(2,4,6-triisopropylphenyl)phosphine
Shigeru Sasaki,*,a Yusuke Shimizu,a and Masaaki Yoshifujia,b
a
Department of Chemistry, Graduate School of Science, Tohoku University
6-3 Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Japan
b
Present address: Department of Chemistry, The University of Alabama, Tuscaloosa, AL 354870336, USA
E-mail: ssasaki@m.tohoku.ac.jp
Supplemental Materials
Experimental procedure
1
H, 13C NMR, UV-Vis, and FT-ICR-MS spectra of 2-iodo-5-methyl-1,3-bis(2-
methylphenyl)benzene
1
H, 13C, and 31P NMR, and FT-ICR-MS spectra of 1
1
H, 13C, and 31P NMR, UV-Vis, and FT-ICR-MS spectra of 4
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Experimental
General
1
H, 13C, and 31P NMR spectra were measured on a Bruker AVANCE 400 or a Bruker AVANCE
III 500 spectrometer. 1H and
13
C NMR chemical shifts are expressed as
from external
tetramethylsilane and calibrated to the residual proton of the deuterated solvent (
chloroform-d) or the carbon of the deuterated solvent (
chemical shifts are expressed as
77.0 for chloroform-d).
7.25 for
31
P NMR
rom external 85% H3PO4. FT-ICR mass spectra were
measured on a Bruker APEX III with electrospray ionization (ESI) or a Bruker SolariX 9.4T
with atmospheric pressure chemical ionization (APCI) or electrospray ionization (ESI). Melting
points were measured on a Yanagimoto MP-J3 apparatus without correction. UV-Vis spectra
were measured on a Shimadzu UV3600 spectrometer. Fluorescence spectra were measured on a
JASCO FP6600 spectrometer. Infrared spectra were measured on a JASCO FTIR 4100A
spectrometer. Microanalyses were performed at Research and Analytical Center for Giant
Molecules, Graduate School of Science, Tohoku University. Cyclic voltammetry was performed
on a BAS CV-50W controller with a glassy carbon, Pt wire, and Ag/0.01 mol L–1 AgNO3/0.1
mol L–1 n-Bu4NClO4/CH3CN as a working, a counter, and a reference electrode, respectively
(Ferrocene/Ferrocenium = 0.18 V in dichloromethane). A substrate (ca. 10–3 mol L–1) was
dissolved in dichloromethane with 0.1 mol L–1 n-Bu4NClO4 as a supporting electrolyte and the
solution was degassed by bubbling with nitrogen gas. Merck silica gel 60 was used for the
column chromatography. All reactions were carried out under an argon atmosphere unless
otherwise specified. n-Butyllithium and tetrahydrofuran (dehydrated, stabilizer free) were
purchased from Kanto Chemical Co., Inc. and used as they were. 1,3-Dibromo-2-iodo-5methylbenzene was synthesized from diazotization of 2,6-dibromotoluidine followed by reaction
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with potassium iodide. Chrorobis(2,4,6-triisopropylphenyl)phosphine was prepared by the
literature method.1
Synthesis
2-Iodo-5-methyl-1,3-bis(2-methylphenyl)benzene
A solution of 2-bromotoluene (7.8 mL, 64.8 mmol) in tetrahydrofuran (30 mL) was added to
magnesium (1.50 g, 61.7 mmol) with stirring and the resultant Grignard reagent was diluted with
tetrahydrofuran (70 mL). A solution of 1,3-dibromo-2-iodo-5-methylbenzene (6.51 g, 17.3
mmol) in tetrahydrofuran (40 mL) was added to the solution of the Grignard reagent in 3 h, and
the mixture was stirred for 12 h. A solution of iodine (6.43 g, 25.3 mmol) in tetrahydrofuran (45
mL) was added to the mixture, and excess iodine was quenched with a sodium hydrogensulfite
solution. The mixture was extracted with ether, washed with a saturated sodium chloride solution,
dried over anhydrous magnesium sulfate, concentrated by rotary evaporator. The residue was
recrystallized
from
n-hexane
to
give
the
first
crop
of
2-iodo-5-methyl-1,3-bis(2-
methylphenyl)benzene (3.23 g, 8.11 mmol, 47%). The filtrate was purified by column
chromatography (SiO2, n-hexane) to give the second crop (630 mg, 1.58 mmol, 9%).
2-Iodo-5-methyl-1,3-bis(2-methylphenyl)benzene: colorless powder; mp 118.8–119.5 °C; 1H
NMR (400 MHz, CDCl3, 300 K, observed as a 1:1 mixture of syn- and anti- isomers)
7.34–
7.21 (m, 6H+6H, syn- and anti-o-tolyl-4,5,6), 7.12 (dm, 2H+2H, JHH = 7.54 Hz, syn- and anti- otolyl-3), 6.996 (s, 2H, syn- or anti- arom), 6.994 (s, 2H, syn- or anti- arom), 2.34 (s, 3H+3H, syn-
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and anti-4-CH3), 2.12 (s, 6H, syn- or anti- CH3), 2.11 (s, 6H, syn- or anti- CH3); 13C NMR (100
MHz, CDCl3, 300 K, observed as a 1:1 mixture of syn- and anti- isomers)
147.44 (syn- or anti-
tolyl-C–CH3), 147.35 (syn- or anti- tolyl-C–CH3), 145.27 (syn- and anti- C–CH3), 137.72 (synor anti- 1,3 or tolyl-1), 137.55 (syn- or anti- 1,3 or tolyl-1), 135.65 (syn- or anti- 1,3 or tolyl-1),
135.59 (syn- or anti- 1,3 or tolyl-1), 129.79, 129.75, 129.24, 128.97, 128.91, 128.89, 127.75,
125.53, 125.45, 101.94 (syn- or anti- I–C), 101.53 (syn- or anti- I–C), 20.82 (syn- and anti- CCH3), 20.08 (syn- or anti- tolyl-CH3), 19.95 (syn- or anti- tolyl-CH3); UV-Vis (dichloromethane)
( )/nm 273sh (2220), 266sh (2890); FT-ICR-MS (APCI) m/z 398.05257 (100%) calcd for
[C21H19I]+, 398.05260; 399.06041 (13%) calcd for [C21H19I+H]+, 399.06042; Found: C 63.34, H
4.83%, I 31.62%. Calcd for C21H19I: C 63.33, H 4.81, I 31.86%.
[4-Methyl-2,6-bis(2-methylphenyl)phenyl]bis(2,4,6-triisopropylphenyl)phosphine (1)
n-Butyllithium (1.62 mol L–1 in n-hexane, 2.1 mL, 3.40 mmol) was added to a solution of 2iodo-5-methyl-1,3-bis(2-methylphenyl)benzene (1.26 g, 3.16 mmol) in tetrahydrofuran (15 mL)
at –78 °C and the solution was stirred for 30 min. Copper(I) chloride (330 mg, 3.33 mmol) was
added and the mixture was warmed to 20 °C and stirred for 3 h, and cooled to –78 °C. A solution
of chlorobis(2,4,6-triisopropylphenyl)phosphine (1.53 g, 3.23 mmol) in tetrahydrofuran (5 mL)
was added to the mixture, and the mixture was warmed and refluxed for 12 h. The mixture was
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cooled to 20 °C, diluted with n-hexane (50 mL), and the insoluble solids were removed by
filtration. The filtrate was concentrated by rotary evaporator and the residue was recrystallized
from pentane-ethanol to give 1 (648 mg, 0.914 mmol, 29%).
1: pale yellow powder; mp 68.1–69.8 °C; 1H NMR (400 MHz, CDCl3. 300 K)
7.09 (d, 2H, JHH
= 7.49 Hz, o-tolyl-3-arom), 6.89 (s, 2H, Tip-3,5-arom), 6.83 (t, 2H, JHH = 7.32 Hz, o-tolyl-4arom), 6.78 (d, 2H, JPH = 2.29 Hz, Ar-3,5-arom), 6.46 (s, 2H, Tip-3,5-arom), 6.43 (d, 2H, JHH =
7.13 Hz, o-tolyl-6-arom), 6.26 (t, 2H, JHH = 7.34 Hz, o-tolyl-5-arom), 3.82 (brs, 2H, 2 or 6CH(CH3)2), 2.75 (sept, 2H, JHH = 6.58 Hz, 2 or 6-CH(CH3)2), 2.82–2.68 (m, 2H, 2 or 6CH(CH3)2), 2.26 (s, 9H, Ar-CH3+o-tolyl-CH3), 1.19 (d, 6H, JHH = 6.71 Hz, CH(CH3)2), 1.18 (d,
6H, JHH = 6.66 Hz, CH(CH3)2), 1.09 (d, 12H, JHH = 6.41 Hz, CH(CH3)2), 0.33 (d, 6H, JHH = 6.62
Hz, 2 or 6-CH(CH3)2), 0.20 (d, 6H, JHH = 6.23 Hz, 2 or 6-CH(CH3)2);
CDCl3, 301.7 K)
13
C NMR (126 MHz,
153.29 (d, J = 18.26 Hz, Tip-2 or 6-arom), 152.41 (d, J = 20.04 Hz Tip-2 or
6-arom), 149.20 (s, Tip-4-arom), 148.13 (d, J = 22.42 Hz Ar-2 or 6), 141.50 (brs, o-tolyl-2-arom),
141.46 (brs, o-tolyl-2-arom), 135.91 (s, Ar-4-arom), 134.59 (s, o-tolyl-1-arom), 133.44 (d, J =
35.48 Hz, Ar-1-arom), 132.97 (brm, Tip-1-arom), 132.06 (brs, Ar-3,5-arom), 131.6–131.2 (brm,
o-tolyl-6-arom) 129.54 (s, o-tolyl-3-arom), 126.19 (s, o-tolyl-4-arom), 123.06 (s, o-tolyl-5-arom),
122.10 (d, J = 4.1 Hz, Tip-3 or 5-arom), 121.49 (d, J = 4.6 Hz, Tip-3 or 5-arom), 34.10 (s, 4CH(CH3)2), 33.26 (d, J = 20.2 Hz, 2 or 6-CH(CH3)2), 31.07 (d, J = 17.8 Hz, 2 or 6-CH(CH3)2),
25.13 (s, CH(CH3)2), 24.12 (s, CH(CH3)2), 23.95 (s, CH(CH3)2), 23.63 (s, CH(CH3)2), 23.45 (s,
CH(CH3)2), 23.27 (s, 4-CH3), 20.69 (s, o-tolyl-CH3), 20.01 (s, o-tolyl-CH3); 31P NMR (162 MHz,
CDCl3, 300 K)
–40.9 (s); UV-Vis (dichloromethane)
( )/nm 334 (12100); FT-ICR-MS
(ESI) m/z 708.4821 (100%), calcd for [C51H65P]+, 708.4818; Found: C 86.01, H 9.36%, calcd for
C51H65P: C 86.39, H 9.24%.
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[4-Methyl-2,6-bis(2-methylphenyl)phenyl]bis(2,4,6-triisopropylphenyl)phosphine oxide (4)
To a mixture of 1 (60.0 mg, 0.0846 mmol) and mCPBA (33.0 mg, 69–75%, 0.13 mmol as 70%),
chloroform (5 mL) was added and the resultant solution, which initially showed a purple color
and turned to colorless, was stirred for 6 h. The mixture was concentrated by rotary evaporator
and the residue was purified by column chromatography (SiO2, n-hexane/ethyl acetate = 1/70) to
give 4 (63.0 mg, quant.). Further purification by chromatography (SiO2, n-hexane, nhexane/chloroform=2/3) and recrystallization from n-hexane-methanol was carried out to reduce
impurities (silicone grease).
4: colorless chunks; mp 196.8–197.5 °C; 1H NMR (500 MHz, CDCl3, 300.1 K)
7.12 (t, 2H, J
= 7.70 Hz, o-tolyl-arom), 7.06 (m, 1H, J = 2.78, 1.85 Hz, Tip-3 or 5-arom), 7.02 (d, 1H, J = 7.42
Hz, o-tolyl-arom), 6.93 (brs, 1H, Tip-3 or 5-arom), 6.92 (brs, 2H, Ar-3,5-arom), 6.86 (d, 1H, J =
7.31 Hz, o-tolyl-arom), 6.83 (d, 1H, J = 7.31 Hz, o-tolyl-arom), 6.79–6.77 (m, 1H, Tip-3 or 5arom), 6.45 (dd, 1H, J = 3.87, 1.47 Hz, Tip-3 or 5-arom), 6.30 (t, 1H, J = 7.41 Hz, o-tolyl-arom),
6.27 (t, 1H, J = 7.41 Hz, o-tolyl-arom), 6.10 (d, 1H, J = 7.56 Hz, o-tolyl-arom), 4.14 (sept, 1H, J
= 6.42 Hz, 2 or 6-CH(CH3)2), 3.06 (sept, 1H, J = 6.46 Hz, 2 or 6-CH(CH3)2), 2.89 (sept, 1H, J =
6.39 Hz, 2 or 6-CH(CH3)2), 2.84 (sept, 1H, J = 6.81 Hz, 4-CH(CH3)2), 2.75 (sept, 1H, J = 6.88
Hz, 4-CH(CH3)2), 2.44 (sept, 1H, J = 6.56 Hz, 2 or 6-CH(CH3)2), 2.42 (s, 3H, o-tolyl-CH3), 2.31
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(3H, s, CH3), 2.09 (3H, s, o-tolyl-CH3), 1.38 (d, 3H, J = 6.80 Hz, 2 or 6-CH(CH3)2), 1.35 (d, 3H,
J = 6.18 Hz, 2 or 6-CH(CH3)2), 1.25 (d, 3H, J = 6.84 Hz, 4-CH(CH3)2), 1.24 (d, 3H, J = 6.86 Hz,
4-CH(CH3)2), 1.161 (d, 3H, J = 6.88 Hz, 4-CH(CH3)2), 1.158 (d, 3H, J = 6.86 Hz, 4-CH(CH3)2),
1.01 (d, 3H, J = 6.54 Hz, 2 or 6-CH(CH3)2), 0.84 (d, 3H, J = 6.40 Hz, 2 or 6-CH(CH3)2), 0.56 (d,
3H, J = 6.36 Hz, 2 or 6-CH(CH3)2), 0.50 (d, 3H, J = 6.86 Hz, 2 or 6-CH(CH3)2), 0.28 (d, 3H, J =
6.60 Hz, 2 or 6-CH(CH3)2), 0.14 (d, 3H, J = 6.36 Hz, 2 or 6-CH(CH3)2); 13C NMR (126 MHz,
CDCl3, 300.6 K)
156.46 (d, JPC = 9.84 Hz, Tip-2 or 6-arom), 155.92 (d, JPC = 9.58 Hz, Tip-2
or 6-arom), 150.73 (d, JPC = 2.40 Hz, Tip-4-arom), 150.71 (d, JPC = 2.31 Hz, Tip-4-arom),
150.30 (d, JPC = 12.41 Hz, Tip-2 or 6-arom), 150.25 (d, JPC = 8.47 Hz, Tip-2 or 6-arom), 147.63
(d, JPC = 10.96 Hz, Ar-2 or 6-arom), 145.63 (d, JPC = 2.62 Hz, o-tolyl-2-arom), 143.78 (d, JPC =
9.59 Hz, Ar-2 or 6-arom), 138.90 (d, JPC = 97.30 Hz, Ar-1-arom), 138.86 (d, JPC = 3.57 Hz, otolyl), 138.43 (d, JPC = 2.50 Hz, Ar-4-arom), 137.69 (s, o-tolyl-1-arom), 136.53 (d, JPC = 94.33
Hz, Tip-1-arom), 135.18 (d, JPC = 88.04 Hz, Tip-1-arom), 134.64 (s, o-tolyl-arom), 134.36 (s, otolyl-arom), 133.31 (d, JPC = 9.77 Hz, Ar-3 or 5-arom), 133.08 (d, JPC = 10.77 Hz, Ar-3 or 5arom), 130.83 (s, o-tolyl-arom), 127.87 (s, o-tolyl-arom), 126.97 (s, o-tolyl-arom), 125.39 (s, otolyl-arom), 124.62 (s, o-tolyl-arom), 123.89 (d, JPC = 10.96 Hz, Tip-3 or 5-arom), 123.77 (d, JPC
= 10.98 Hz, Tip-3 or 5-arom), 122.43 (s, o-tolyl-arom), 122.39 (s, o-tolyl-arom), 122.22 (d, JPC =
10.96 Hz, Tip-3 or 5-arom), 121.54 (d, JPC = 11.12 Hz, Tip-3 or 5-arom), 34.11 (s, 4-CH), 34.10
(d, JPC = 4.45 Hz, 2 or 6-CH), 34.01 (s, 4-CH), 33.38 (d, JPC = 2.98 Hz, 2 or 6-CH), 31.45 (d, JPC
= 7.98 Hz, 2 or 6-CH), 31.40 (d, JPC = 4.91 Hz, 2 or 6-CH), 27.23 (s, CH(CH3)2), 25.50 (s,
CH(CH3)2), 25.39 (s, CH(CH3)2), 24.45 (s, CH(CH3)2), 24.21 (s, CH(CH3)2), 24.05 (s,
CH(CH3)2), 24.03 (s, CH(CH3)2), 23.97 (s, CH(CH3)2), 23.88 (s, CH(CH3)2), 23.67 (s,
CH(CH3)2), 23.59 (s, CH(CH3)2), 23.34 (s, CH(CH3)2), 20.97 (s, o-tolyl-CH3), 20.78 (s, 4-CH3),
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19.96 (s, o-tolyl-CH3);
(dichloromethane)
31
P NMR (202 MHz, CDCl3, 300.6 K)
24.9 (s); UV-Vis
( )/nm 289 (3990); FT-ICR-MS (ESI) m/z 725.48454 (100%) calcd for
[C51H65OP+H]+, 725.48458; 747.46666 (8%) calcd for [C51H65OP+Na]+, 747.46652; Found: C
81.97, H 9.05%, calcd for C51H65OP•0.5(SiMe2O): C 81.95, H 8.99%.
References
1) S. Sasaki, F. Murakami, M. Murakami, M. Watanabe, K. Kato, K. Sutoh, and M. Yoshifuji, J.
Organomet. Chem., 690(10), 2664–2672 (2005).
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Figure S 1. 1H NMR (400 MHz, CDCl3, 300 K) spectra of 2-iodo-5-methyl-1,3-bis(2methylphenyl)benzene
S 10
Figure S 2.
13
C NMR (101 MHz, CDCl3, 300 K) spectra of 2-iodo-5-methyl-1,3-bis(2-
methylphenyl)benzene
S 11
Figure S 3. UV-Vis spectrum of 2-iodo-5-methyl-1,3-bis(2-methylphenyl)benzene in
dichloromethane
S 12
Figure S 4. FT-ICR-MS (APCI) spectrum of 2-iodo-5-methyl-1,3-bis(2-methylphenyl)benzene
S 13
Figure S 5. 1H NMR (400 MHz, CDCl3, 300 K) spectra of 1
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Figure S 6. 13C NMR (126 MHz, CDCl3, 301.7 K) spectra of 1
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Figure S 7. 31P NMR (162 MHz, CDCl3, 300 K) spectra of 1
S 16
Figure S 8. FT-ICR-MS (ESI) spectrum of 1.
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Figure S 9. 1H NMR (500 MHz, CDCl3, 300.1 K) spectra of 4
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Figure S 10. 13C NMR (126 MHz, CDCl3, 300.6 K) spectra of 4
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Figure S 11. 31P NMR (202 MHz, CDCl3, 300.6 K) spectra of 4
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Figure S 12. UV-Vis spectrum of 4 in dichloromethane
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Figure S 13. FT-ICR-MS (ESI) spectrum of 4