A R T I C L E S
Yamashita et al.
Synthesis of 1-Diphenylphosphino-1′-bis(4-trifluoromethylphe-
nyl)phosphino-ferrocene (17, DPPF-Ph,CF3). A solution of n-
butyllithium in hexane (2.5 M; 0.88 mL, 2.2 mmol) was added to a
solution of 1-bromo-1′-diphenylphosphinoferrocene (898 mg, 2.00
mmol) in THF (50 mL) at -78 °C under nitrogen in Schlenk flask.
The resulting solution was stirred for 1 h at -78 °C. ClP(C6H4-p-CF3)2
(824 mg, 2.31 mmol) was then added at -78 °C, and the solution was
stirred at room temperature for 4 h. The reaction mixture was poured
into water (50 mL) and extracted with CH2Cl2. The combined organic
layer was dried over Na2SO4 and evaporated under reduced pressure.
The residue was purified twice by silica gel chromatography (CH2Cl2/
hexane ) first 10%; second 0-10%) to give an orange solid (746 mg,
Hz, 2H); 31P{1H} NMR (THF-d8, 162 MHz); major isomer, δ 9.1 (d,
J ) 33 Hz), 25.7 (d, J ) 33 Hz); minor isomer, δ 8.9 (d, J ) 34 Hz),
25.0 (d, J ) 34 Hz); 19F{1H} NMR (THF-d8, 376 MHz); major isomer,
δ -62.7 (s, 6F), -61.6 (s, 3F); minor isomer, δ -63.0 (s, 6F), -61.7
(s, 3F); Anal. Calcd. for C43H30F9FeIP2Pd: C, 48.32; H, 2.83. Found:
C, 48.54; H, 2.75; 21a,b: 1H NMR data of the Cp and OMe groups
(THF-d8, 400 MHz); major isomer, δ 3.76 (s, 3H), 3.80 (q, J ) 1.6
Hz, 2H), 4.29 (t, J ) 1.6 Hz, 2H), 4.60 (brs, 2H), 4.76 (q, J ) 1.6 Hz,
2H); minor isomer, 3.73 (q, J ) 1.6 Hz, 2H), 3.86 (s, 3H), 4.23 (t, J
) 1.6 Hz, 2H), 4.61 (brs, 2H), 4.80 (q, J ) 1.6 Hz, 2H); 31P{1H} NMR
(THF-d8, 162 MHz); major isomer, δ 9.2 (d, J ) 33 Hz), 23.9 (d, J )
33 Hz); minor isomer, δ 6.2 (d, J ) 35 Hz), 25.0 (d, J ) 35 Hz);
19F{1H} NMR (THF-d8, 376 MHz); major isomer, δ -62.7 (s, 6F),
-61.4 (s, 3F); minor isomer, δ -63.0 (s, 6F), -61.7 (s, 3F); major:
minor ) 7.2:1; Anal. Calcd. for C45H34F9FeIO2P2Pd: C, 47.88; H, 3.04.
Found: C, 47.79; H, 3.00.
1
54%). H NMR (CDCl3, 400 MHz) δ 3.98 (m, 4H); 4.28 (m, 2H);
4.37 (m, 2H); 7.24-7.30 (m, 10H); 7.33-7.39 (m, 4H), 7.55 (d, J )
8.0 Hz, 4H); 31P{1H} NMR (CDCl3, 202 MHz) δ -17.1 (s), -15.8
(s); 19F{1H} NMR (CDCl3, 376 MHz) δ -62.1 (s); Anal. Calcd. For
C36H26F6P2Fe: C, 62.63; H, 3.80. Found: C, 62.74; H, 3.84.
General Procedure for Generation of (LL′)Pd(C6H4-4-CF3)NMe-
(C6H4-4-Me) (LL′ ) DPPF-OMe,Ph (22a,b), DPPF-Ph,CF3 (23a,b),
and DPPF-OMe,CF3 (24a,b)). In drybox, (LL′)Pd(C6H4-4-CF3)I (LL′
) Ph,OMe-DPPF (19a,b, 9.3 mg, 10 µmol), Ph,CF3-DPPF (20a,b, 10.7
mg, 10.0 µmol), or OMe-CF3-DPPF (21a,b, 10.7 mg, 10.0 µmol) was
placed into a 4-mL vial and was dissolved in THF-d8 (300 µL). The
solution was transferred to screw-capped NMR tube and the NMR tube
was removed from the drybox. A potassium N-methyltoluidide solution
(0.150 M in THF-d8, 100 µL, 15.0 µmol) was added at -78 °C to the
solution of palladium complex (with a gastight syringe sealed with
Teflon tape). After shaking the mixture, the NMR tube was quickly
placed into a pre-cooled NMR spectrometer probe (-45 °C). The
palladium amido complexes were confirmed by NMR spectroscopy at
-45 °C. 22a,b: 1H NMR data of tolyl methyl and N-methyl groups
(THF-d8, 500 MHz, -45 °C); major isomer, δ 1.95 (s, 3H, Tol-Me),
2.11 (s, 3H, NMe); minor isomer, δ 1.97 (s, 3H, Tol-Me), 2.14 (s, 3H,
NMe); 31P{1H} NMR (THF, 162 MHz, -45 °C); major isomer, δ 8.9
(br), 21.4 (d, J ) 38 Hz); minor isomer, δ 6.7 (br), 24.3 (d, J ) 39
Hz); 19F{1H} NMR (THF, 376 MHz, -15 °C); major isomer, δ -60.5
(s); minor isomer, δ -60.6 (s); major: minor ) 1.3:1; 23a,b: 1H NMR
data of tolyl methyl and N-methyl groups (THF-d8, 500 MHz, -45
°C); major isomer, δ 1.94 (s, 3H, Tol-Me), 2.24 (s, 3H, NMe); minor
isomer, δ 1.96 (s, 3H, Tol-Me), 2.12 (s, 3H, NMe); 31P{1H} NMR
(THF, 162 MHz, -45 °C); major isomer, δ 8.2 (br), 23.3 (d, J ) 37
Hz); minor isomer, δ 7.6 (br), 25.3 (d, J ) 40 Hz); 19F{1H} NMR
(THF, 376 MHz, -15 °C); major isomer, δ -60.7 (s, 3F), -61.8 (s,
3F), -62.1 (s, 3F); minor isomer, δ -60.8 (s, 3F), -62.0 (s, 3F), -62.3
(s, 3F); major: minor ) 3.0:1; 24a,b: 1H NMR data of tolyl methyl
and N-methyl groups (THF-d8, 500 MHz, -45 °C); major isomer, δ
1.95 (s, 3H, Tol-Me), 2.27 (s, 3H, NMe); minor isomer, δ 1.99 (s, 3H,
Tol-Me), 2.16 (s, 3H, NMe); 31P{1H} NMR (THF, 162 MHz, -45 °C);
major isomer, δ 8.0 (br), 20.5 (d, J ) 37 Hz); minor isomer, δ 5.1
(br), 25.4 (d, J ) 40 Hz); 19F{1H} NMR (THF, 376 MHz, -15 °C);
major isomer, δ -60.6 (s, 3F), -61.8 (s, 3F), -62.1 (s, 3F); minor
isomer, δ -60.8 (s, 3F), -62.0 (s, 3F), -62.3 (s, 3F); major: minor )
5.8:1.
Synthesis of 1-Bis(4-methoxyphenyl)phosphino-1′-bis(4-trifluo-
romethylphenyl)-ferrocene (18, DPPF-OMe,CF3). A solution of
n-butyllithium in hexane (2.5 M; 0.85 mL, 2.1 mmol) was added to a
solution of 1-bromo-1′-bis(4-methoxyphenyl)phosphinoferrocene (1.08
g, 2.12 mmol) in THF (40 mL) at -78 °C under nitrogen in Schlenk
flask. The resulting solution was stirred for 1.5 h at -78 °C. A solution
of ClP(C6H4-p-CF3)2 (820 mg, 2.3 mmol) in THF (5 mL) was then
added to the reaction mixture at -78 °C, and the solution was stirred
at room temperature for 1 h. The solvents were removed under reduced
pressure, and the crude product was purified by silica gel chromatog-
raphy (CH2Cl2/hexane ) 50-100%) to give an orange solid (1.28 g,
83%). 1H NMR (CDCl3, 400 MHz) δ 3.81 (s, 6H), 3.98 (m, 2H), 4.02
(m, 2H), 4.22 (m, 2H), 4.36 (m, 2H), 6.85 (d, J ) 8.5 Hz, 4H), 7.23
(m, 4H), 7.41 (t, J ) 7.6 Hz, 4H), 7.56 (d, J ) 7.8 Hz, 4H); 31P{1H}
NMR (CDCl3, 202 MHz) δ -20.7 (s), -15.5 (s); 19F{1H} NMR
(CDCl3, 376 MHz) δ -62.1 (s); Anal. Calcd. For C38H30F6O2P2Fe: C,
60.79; H, 4.03. Found: C, 61.01; H, 4.17.
General Synthetic Procedure for (LL′)Pd(C6H4-p-CF3)I (LL′ )
DPPF-OMe,Ph (19a,b), DPPF-Ph,CF3 (20a,b), and DPPF-OMe,CF3
(21a,b)). In a glovebox, a solution of unsymmetrical ligand LL′ (Ph,-
OMe-DPPF (16, 399 mg, 0.650 mmol), Ph,CF3-DPPF (17, 171 mg,
0.248 mmol), or OMe,CF3-DPPF (18, 810 mg, 1.11 mmol)) in THF (4
mL for 16, 2 mL for 17, 5 mL for 18) was added at room temperature
to a solution of (TMEDA)Pd(C6H4-p-CF3)I (300 mg, 0.607 mmol for
19a,b, 109 mg, 0.220 mmol for 20a,b, or 495 mg, 1.00 mmol for 21a,b)
in THF (4 mL for 19a,b, 2 mL for 20a,b, or 5 mL for 21a,b). After
stirring for 5 min at room temperature, solvents were removed under
reduced pressure until the volume was about 2 mL or 4 mL for 19a,b
or 21a,b, or until the solvents were completely removed for 20a,b.
The resulting solution of 19a,b and 21a,b in THF or solution of 20a,b
in 2 mL of ether was added dropwise at room temperature to vigorously
stirred pentane (18 mL) to give yellow precipitate. The resulting yellow
powder was isolated by filtration through a glass fritted funnel to afford
the product (561 mg, 93% for 19a,b, 187 mg, 79% for 20a,b, 928 mg,
82% for 21a,b) as a mixture of 2 regioisomers (major: minor ) 1.2:1
Synthesis of H15NMePh.109,110 In a drybox, 15N-aniline (410 mg,
4.40 mmol) and K2CO3 (1.20 g, 8.65 mmol) were placed into a 20 mL
vial. After addition of THF (5 mL), the vial was sealed with a rubber
septum and was removed from the drybox. Water (5 mL) and Boc2O
(Di-tert-butyl dicarbonate, 1.15 mL, 5.00 mmol) were added to the
vial at room temperature. The resulting solution was stirred for 19 h at
room temperature, and the reaction was quenched by addition of water.
After extraction of the reaction mixture with CH2Cl2, and the combined
organic phase was dried with Na2SO4. Removal of solvents afforded a
white solid (1.02 g) of the BOC-protected 15N-labeled aniline. This
solid was brought into a drybox and dissolved in DMF (4 mL). MeI
1
for 19a,b; 2.7:1 for 20a,b; 7.2:1 for 21a,b; calculated from H and
19F{1H} NMR spectra). 19a,b: 1H NMR data for Cp and OMe groups
(THF-d8, 400 MHz) major isomer, δ 3.72 (br, 2H), 3.74 (s, 3H), 4.20
(brs, 2H), 4.51 (brs, 2H), 4.73 (m, 2H); minor isomer, 3.67 (br, 2H),
3.85 (s, 3H), 4.16 (brs, 2H), 4.53 (brs, 2H), 4.75 (m, 2H); 31P{1H}
NMR (THF-d8, 162 MHz); major isomer, δ 9.1 (d, J ) 33 Hz), 23.7
(d, J ) 33 Hz); minor isomer, δ 6.3 (d, J ) 34 Hz), 26.2 (d, J ) 34
Hz); 19F{1H} NMR (THF-d8, 376 MHz); major isomer, δ -62.7 (s,
6F), -61.6 (s, 3F); minor isomer, δ -63.0 (s, 6F), -61.7 (s, 3F); Anal.
Calcd. for C43H36F3FeIO2P2Pd: C, 52.02; H, 3.65. Found: C, 51.78;
H, 3.53; 20a,b: 1H NMR data of the Cp groups (THF-d8, 400 MHz);
major isomer, δ 3.76 (q, J ) 1.6 Hz, 2H), 4.28 (t, J ) 1.6 Hz, 2H),
4.63 (brs, 2H), 4.85 (q, J ) 1.6 Hz, 2H); minor isomer, 3.73 (q, J )
1.6 Hz, 2H), 4.26 (t, J ) 1.6 Hz, 2H), 4.60 (brs, 2H), 4.82 (q, J ) 1.6
(109) Macleod, C.; McKiernan, G. J.; Guthrie, E. J.; Farrugia, L. J.; Hamprecht,
D. W.; Macritchie, J.; Hartley, R. C. J. Org. Chem. 2003, 68, 387-401.
(110) Peterson, M. A.; Nilsson, B. L. Synth. Commun. 1999, 29, 3821-3827.
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16358 J. AM. CHEM. SOC. VOL. 125, NO. 52, 2003