Organometallics
Article
extracted with DCM (20 mL), and the combined organic layers were
dried over sodium sulfate. After removal of the solvent under reduced
pressure, column chromatography on silica gel (ethyl acetate/
methanol 19/1 → 9/1 → DCM/methanol 9/1), and drying under
high vacuum, the product was obtained as a yellowish brown oil (438
pressure, and the residue was purified by column chromatography on
silica gel (hexanes/ethyl acetate/methanol 50/50/1 → 25/25/1 →
DCM/methanol 10/1). After drying under high vacuum, the product
was obtained as a yellow solid (150 mg, 0.21 mmol, 56%). NMR:
Calcd for C32H43BrN4O3Pd (718.04): C, 53.53; H, 6.04; N, 7.80.
Found: C, 53.22; H, 6.28; N, 7.51. ESI-MS: 637.4 ([LL′Pd]+). Mp:
67 °C.
General Catalytic Procedure. All solid reagents and a magnetic
stirring bar were placed in a 10 mL crimp vial, and the vial was capped
by a butyl rubber septum. The vial was evacuated and subsequently
filled with argon three times. Then, the solvent and all liquid reagents
were added via syringe. The vial was placed in a preheated aluminum
block and stirred for the indicated time. For determination of the GC
yield, DCM (2 mL) and dodecane (175 mg), as an internal standard,
were added, and aliquots of 50 μL of the organic layer were placed
onto a plug of silica and rinsed with DCM (3 mL). The obtained
solution was analyzed by GC-MS. The yield was determined using a
calibration curve. All yields given are an average of two separate runs.
For the determination of the isolated yields, water (5 mL) was added
and the mixture was extracted with DCM (3 × 10 mL). The solvent
was evaporated under reduced pressure, the residue was dissolved in a
solution was filtered over silica. For reactions without full conversion,
the raw product was purified by column chromatography. The
product was dried under reduced pressure at 50 °C. Product
1
mg, 0.48 mmol, 72%). H NMR (500 MHz, CDCl3): δ (ppm) 6.91
(dd, J = 7.6 Hz, J = 0.9 Hz, 2 H, Har), 6.73−6.81 (m, 4 H, Har), 6.68
(td, J = 7.3 Hz, J = 1.9 Hz, 2 H, Har), 6.43 (d, 3J = 1.6 Hz, 2 H, NCH),
a
6.37 (d, 3J = 1.6 Hz, 2 H, NCH), 3.98−4.15 (m, 2 H, NCH2 ), 3.81−
b
3.94 (m, 2 H, NCH2 ), 3.62−3.78 (m, 4 H, CH2), 3.52−3.62 (m, 12
H, CH2), 3.48 (q, 3J = 4.5 Hz, 4 H, MeOCH2), 3.35 (s, 6 H, OCH3),
2.21 (s, 6 H, CH3). Mixture of trans/cis isomers (approximately 6:1).
For clarity, only the peaks of the trans isomer are given. 13C NMR (126
MHz, CDCl3): δ (ppm) 181.2 (s, C(O)), 151.6 (s, Car), 147.5 (s,
Car), 134.4 (s, Car), 132.7 (s, CHar), 126.3 (s, CHar), 125.7 (s, NCH),
122.7 (s, CHar), 119.7 (s, CHar), 119.6 (s, NCH), 71.8 (s, CH2), 70.8
(s, CH2), 70.57 (s, CH2), 70.59 (s, CH2), 69.2 (s, CH2), 59.0 (s,
OCH3), 47.0 (s, NCH2), 24.6 (s, CH3). Mixture of trans/cis isomers
(approximately 6:1). For clarity, only the peaks of the trans isomer are
given. Anal. Calcd for C36H48N4O10Pd2 (909.64): C, 47.54; H, 5.32;
N, 6.16. Found: C, 47.56; H, 5.05; N, 6.41. ESI-MS: 395.2 ([L −
Pd]+), 851.3 ([L2Pd2(OAc)]+).
Complex 6. 1,3-Bis(2,6-diisopropylphenyl)imidazolium chloride
(283 mg, 0.67 mmol, 2 equiv), compound 4 (303 mg, 0.33 mmol),
KCl (298 mg, 4.00 mmol, 12 equiv), and potassium carbonate (465
mg, 3.33 mmol, 10 equiv) were suspended in THF (15 mL) and were
stirred at 50 °C for 16 h. The mixture was filtered, the solvent was
evaporated under reduced pressure, and the residue was purified by
column chromatography on silica gel (DCM/ethyl acetate 9/1). The
product was dissolved in diethyl ether (10 mL) and precipitated by
addition of hexanes (40 mL). After drying under high vacuum at 50
°C, the product was obtained as a light yellow solid (436 mg, 0.53
mmol, 80%). 1H NMR (600 MHz, CDCl3): δ (ppm) 7.36 (t, 3J = 7.9
Hz, 2 H, Har), 7.27−7.31 (m, 3 H, Har, NCH), 7.21 (s, 2 H, Har), 7.16
ASSOCIATED CONTENT
* Supporting Information
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S
The Supporting Information is available free of charge on the
3
3
(d, J = 1.5 Hz, 1 H, NCH), 7.15 (d, J = 1.5 Hz, 1 H, NCH), 7.08
(dd, 3J = 7.9 Hz, 4J = 1.1 Hz, 1 H, Har), 6.88 (td, 3J = 7.6 Hz, 4J = 1.3
Hz, 1 H, Har), 6.79 (td, 3J = 7.4, 4J = 1.3 Hz, 1 H, Har), 6.72 (dd, 3J =
7.5 Hz, 4J = 0.8 Hz, 1 H, Har), 6.65 (d, 3J = 1.9 Hz, 1 H, NCH), 4.26
Characterization data for the synthesized compounds,
details for the solid-state structure determination of
compound 6, and NMR spectra (PDF)
3
3
(t, J = 5.6 Hz, 2 H, NCH2), 3.76 (t, J = 5.6 Hz, 2 H, NCH2CH2),
3.51−3.54 (m, 3 H, CH2), 3.47−3.51 (m, 3 H, CH2), 3.40−3.44 (m,
2 H, CH2), 3.31 (s, 3 H, OCH3), 3.30 (spt, 3J = 6.0 Hz, 4 H, CHiPr),
1.48 (d, 3J = 6.4 Hz, 6 H, CH3), 1.16 (d, 3J = 6.8 Hz, 6 H, CH3), 1.01
(d, 3J = 6.8 Hz, 6 H, CH3), 0.78 (d, 3J = 6.4 Hz, 6 H, CH3). 13C NMR
(151 MHz, CDCl3): δ (ppm) 180.1 (s, Car) 152.6 (s, Car), 152.2 (s,
Car), 147.8 (s, Car), 145.0 (s, Car), 138.0 (s, CHar), 137.4 (s, Car),
136.1 (s, Car), 129.8 (s, CHar), 127.4 (s, CHar), 125.9 (s, CHar), 124.8
(s, CHar), 124.2 (s, CHar), 123.9 (s, CHar), 122.6 (s, CHar), 120.9 (s,
CHar), 120.1 (s, CHar), 71.8 (s, CH2), 70.8 (s, CH2), 70.52 (s, CH2),
70.49 (s, CH2), 69.4 (s, CH2), 68.5 (s, CH2), 59.0 (s, OCH3), 47.4 (s,
CH2), 29.0 (s, CHiPr) 28.4 (s, CHiPr), 26.5 (s, CH3,iPr), 26.1 (s,
CH3,iPr), 23.2 (s, CH3,iPr), 23.0 (s, CH3,iPr). Anal. Calcd for
C43H57ClN4O3Pd (819.82): C, 63.00; H, 7.01; N, 6.83. Found: C,
63.03; H, 7.39; N, 6.70. ESI-MS: 783.6 ([LL′Pd]+). Mp: 78 °C.
Complex 7. Compound 3 (120 mg, 0.26 mmol, 2 equiv),
compound 4 (120 mg, 0.13 mmol), KBr (188 mg, 1.58 mmol, 12
equiv), and potassium carbonate (184 mg, 1.32 mmol, 10 equiv) were
suspended in THF (10 mL) and stirred at 50 °C for 16 h. The
mixture was filtered off, the solvent was evaporated under reduced
pressure, and the residue was purified by column chromatography on
silica gel (DCM/ethyl acetate 9/1). After drying under high vacuum,
the product was obtained as a yellow, hygroscopic oil (96 mg, 0.11
mmol, 43%). NMR: complex spectrum. Please see the Supporting
Information. Anal. Calcd for C38H55BrN4O6Pd·0.7H2O (850.2): C,
53.29; H, 6.99; N, 6.55. Found: C, 52.90; H, 6.59; N, 6.49. ESI-MS:
769.6 ([LL′Pd]+).
Accession Codes
CCDC 1863544 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
bridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
AUTHOR INFORMATION
Corresponding Author
■
ORCID
Notes
The authors declare no competing financial interest.
REFERENCES
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(1) Metal-Catalyzed Cross-Coupling Reactions and More; de Meijere,
̈
A., Brase, S., Oestreich, M., Eds.; Wiley-VCH: Weinheim, 2014.
(2) Beletskaya, I. P.; Averin, A. D. New trends in the cross-coupling
and other catalytic reactions. Pure Appl. Chem. 2017, 89, 1413−1428.
(3) Kotha, S.; Lahiri, K.; Kashinath, D. Recent applications of the
Suzuki − Miyaura cross-coupling reaction in organic synthesis.
Tetrahedron 2002, 58, 9633−9695.
(4) Nicolaou, K. C.; Bulger, P. G.; Sarlah, D. Palladium-catalyzed
cross-coupling reactions in total synthesis. Angew. Chem., Int. Ed.
2005, 44, 4442−4489.
(5) Fyfe, J.; Watson, A. Strategies towards Chemoselective Suzuki−
Miyaura Cross-Coupling. Synlett 2015, 26, 1139−1144.
Complex 8. Compound 3 (169 mg, 0.37 mmol, 2 equiv),
compound 5 (120 mg, 0.19 mmol), KBr (266 mg, 2.2 mmol, 12
equiv), and potassium carbonate (260 mg, 1.9 mmol, 10 equiv) were
suspended in THF (15 mL) and stirred at 50 °C for 2 days. The
mixture was filtered, the solvent was evaporated under reduced
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Organometallics XXXX, XXX, XXX−XXX