R. N. Prabhu, G. N. Babu and S. Pal
mogeneous catalysts for the formation of diaryl ketones from
arylboronic acids and aryl aldehydes.
Me). 13C NMR ((CD3)2SO; 100 MHz, δ, ppm): 178.43 (C2), 149.33
(C11), 146.56 (C13), 138.39 (C4), 134.46 (C10), 129.46 (C9), 129.27
(C16), 128.51 (C3), 128.43 (C7), 127.64 (C6), 126.25 (C1), 125.74 (C15),
123.44 (C12), 120.13 (C5), 118.11 (C8), 116.25 (C17), 108.10 (C14),
20.82 (Me). UV–visible (Me2NCHO; λmax, nm (ε, 105 Mꢀ1 cmꢀ1)):
474 (8.8), 452 (8.9), 425sh (6.1), 360sh (3.1), 318 (4.7).
Experimental
Materials
H2L3 (R = Cl). Yield 76%. LC–MS (m/z): calcd for (M + H)+: 298.73.
Found: 298.30. Anal. Calcd for C17H12NO2Cl (297.73) (%): C, 68.58; H,
4.06; N, 4.70. Found (%): C, 68.46; H, 4.12; N, 4.65. Selected IR bands
(KBr; cmꢀ1): 3480, 1633, 1607. 1H NMR ((CD3)2SO; 400 MHz, δ, ppm):
15.66 (d, J = 9 Hz, 1H, NH), 10.59 (s, 1H, OH), 9.54 (d, J = 9 Hz, 1H,
H11), 8.48 (d, J = 8 Hz, 1H, H8), 8.14 (s, 1H, H17), 7.84 (d, J = 9 Hz,
1H, H4), 7.71 (d, J = 8 Hz, 1H, H5), 7.51 (dd, J = 8, 8 Hz, 1H, H7), 7.30
(dd, J = 8, 8 Hz, 1H, H6), 7.14 (d, J = 8 Hz, 1H, H15), 7.00 (d,
J = 8 Hz, 1H, H14), 6.82 (d, J = 9 Hz, 1H, H3). 13C NMR ((CD3)2SO;
100 MHz, δ, ppm): 177.55 (C2), 150.68 (C11), 147.96 (C13), 138.65
(C4), 134.27 (C10), 130.74 (C12), 129.45 (C5), 128.57 (C7), 126.52
(C16), 126.46 (C15), 125.14 (C3), 124.11 (C9), 123.78 (C6), 120.68 (C8),
2-Hydroxy-1-naphthaldehyde, 2-amino-4-R-phenols (R = H, Me and
Cl) and the substrates (aldehydes and boronic acid derivatives) for
the cross-coupling reactions were obtained from Sigma Aldrich
and used as received. PdCl2 was purchased from Arora Matthey
Ltd., India, and used without further purification. All other chemicals
and solvents used in this work were of reagent grade available
commercially and used as supplied.
Physical Measurements
Microanalyses (CHN) were performed using a Thermo Finnigan
Flash EA1112 series elemental analyser. Magnetic susceptibility
measurements were performed with a Sherwood scientific balance.
A Shimadzu LCMS 2010 liquid chromatograph–mass spectrometer
(LC–MS) was used to verify the purity of the Schiff bases (H2L1–3).
The solution electrical conductivities were measured using a
Digisun DI-909 conductivity meter. The infrared (IR) spectra were re-
corded with a Jasco-5300 FT-IR spectrophotometer. A Shimadzu
UV-3600 UV–VIS–NIR spectrophotometer was used to obtain the
electronic spectra. The NMR spectra were recorded with a Bruker
spectrometer.
117.76 (C17), 117.56 (C14), 108.66 (C1). UV–visible (Me2NCHO; λmax
,
nm (ε, 105 Mꢀ1 cmꢀ1)): 470 (10.0), 453 (9.6), 395sh (4.1), 322 (5.3).
General Procedure for Synthesis of [Pd(Ln)(PPh3)] (1–3)
To a solution of H2Ln (0.2 mmol) and Et3N (0.3 ml) in toluene (20 ml),
solid [Pd(PPh3)2Cl2] (0.2 mmol) was added. The reaction mixture
was stirred under reflux for 1 h and the progress of the reaction
was monitored using TLC. At the end of the reaction, the reaction
mixture was cooled to room temperature and filtered to remove
the precipitate of Et3NHCl. The filtrate containing the complex
was evaporated under reduced pressure and the solid obtained
was washed thoroughly with n-hexane, cold ethanol and diethyl
ether, and finally dried in air. The complexes were thus obtained
as orange solids in 69–73% yields.
General Procedure for Preparation of H2L1–3
The Schiff bases (H2L1–3) were prepared by condensation reactions
of 2-hydroxy-1-napthaldehyde (10 mmol) with substituted 2-
amino-4-R-phenols (R = H, Me and Cl) (10 mmol) in refluxing etha-
nol (20 ml) in the presence of glacial acetic acid (0.3 ml). The yellow
solid that separated on cooling the reaction mixture was filtered,
washed with cold ethanol and diethyl ether, and finally dried in
vacuum.
[Pd(L1)(PPh3)] (1). Yield 70%. Anal. Calcd for C35H26NO2PPd
(629.94) (%): C, 66.73; H, 4.16; N, 2.22. Found (%): C, 66.53; H, 4.09;
N, 2.28. Selected IR bands (KBr; cmꢀ1): 1600 (C¼N); 744, 695, 515
1
(PPh3). H NMR ((CD3)2SO; 400 MHz, δ, ppm): 9.79 (d, J = 17 Hz,
1H, H11), 8.70 (d, J = 8 Hz, 1H, H5), 8.36 (d, J = 8 Hz, 1H, H17), 7.78–
7.72 (m, 8H, PPh3 ortho Hs, H4, H8), 7.65–7.58 (m, 10H, PPh3
meta/para Hs, H7), 7.34 (dd, J = 8, 8 Hz, 1H, H6), 7.04 (dd, J = 8,
8 Hz, 1H, H15), 6.78 (d, J = 8 Hz, 1H, H3), 6.70 (dd, J = 8, 8 Hz, 1H,
H16), 6.63 (d, J = 8 Hz, 1H, H14). 13C NMR ((CD3)2SO; 100 MHz, δ,
ppm): 167.59 (C13), 167.56 (C2), 163.60 (C11), 142.60 (C12), 139.38
H2L1 (R = H). Yield 80%. LC–MS (m/z): calcd for (M + H)+: 264.29.
Found: 263.95. Anal. Calcd for C17H13NO2 (263.28) (%): C, 77.55; H,
4.98; N, 5.32. Found (%): C, 77.42; H, 4.91; N, 5.38. Selected IR bands
(KBr; cmꢀ1): 3483, 1633, 1622. 1H NMR ((CD3)2SO; 400 MHz, δ, ppm):
15.74 (d, J = 10 Hz, 1H, NH), 10.36 (s, 1H, OH), 9.52 (d, J = 10 Hz, 1H,
H11), 8.40 (d, J = 8 Hz, 1H, H8), 7.95 (d, J = 8 Hz, 1H, H17), 7.81 (d,
J = 9 Hz, 1H, H4), 7.68 (d, J = 8 Hz, 1H, H5), 7.49 (dd, J = 8, 8 Hz,
1H, H7), 7.27 (dd, J = 8, 8 Hz, 1H, H6), 7.12 (dd, J = 8, 8 Hz, 1H, H15),
7.03 (d, J = 8 Hz, 1H, H14), 6.96 (dd, J = 8, 8 Hz, 1H, H16), 6.81 (d,
J = 9 Hz, 1H, H3). 13C NMR ((CD3)2SO; 100 MHz, δ, ppm): 178.12
(C2), 149.87 (C11), 148.91 (C13), 138.41 (C4), 134.40 (C10), 129.46
(C5), 129.04 (C9), 128.56 (C7), 127.21 (C15), 126.31 (C12), 125.58 (C3),
123.49 (C6), 120.29 (C14), 120.19 (C8), 118.04 (C17), 116.43 (C16),
108.17 (C1). UV–visible (Me2NCHO; λmax, nm (ε, 105 Mꢀ1 cmꢀ1)):
470 (9.2), 448 (9.2), 422sh (6.3), 355sh (3.6), 325 (5.4).
2
4
(C9), 134.63 (d, JC,P = 9 Hz, Co. of PPh3), 131.82 (d, JC,P = 2 Hz, Cp
of PPh3), 129.31 (d, JC,P = 9 Hz, Cm of PPh3), 129.11 (C15), 128.94
3
(d, 1JC,P = 23 Hz, Ci of PPh3), 128.66 (C10), 128.03 (C5), 127.19 (C17),
124.47 (C7), 123.21 (C8), 121.59 (C6), 119.07 (C16), 116.90 (C3),
115.55 (C14), 111.41 (C1). 31P NMR ((CD3)2SO; 160 MHz, δ, ppm):
22.30. UV–visible (Me2NCHO; λmax, nm (ε, 104 Mꢀ1 cmꢀ1)): 473
(10.8), 449 (10.7), 425sh (7.0), 355sh (3.6), 326 (5.6).
[Pd(L2)(PPh3)] (2). Yield 73%. Anal. Calcd for C36H28NO2PPd
(644.01) (%): C, 67.14; H, 4.38; N, 2.17. Found (%): C, 67.28; H, 4.41;
N, 2.14. Selected IR bands (KBr; cmꢀ1): 1609 (C¼N); 747, 695, 516
H2L2 (R = Me). Yield 83%. LC–MS (m/z): calcd for (M + H)+: 278.32.
Found: 278.15. Anal. Calcd for C18H15NO2 (277.31) (%): C, 77.96; H,
5.45; N, 5.05. Found (%): C, 78.12; H, 5.41; N, 5.13. Selected IR bands
(KBr; cmꢀ1): 3486, 1633, 1614. 1H NMR ((CD3)2SO; 400 MHz, δ, ppm):
15.71 (d, J = 10 Hz, 1H, NH), 10.10 (s, 1H, OH), 9.49 (d, J = 10 Hz, 1H,
H11), 8.40 (d, J = 8 Hz, 1H, H8), 7.81 (s, 1H, H17), 7.80 (d (partially
merged with H17 singlet), J = 9 Hz, 1H, H4), 7.67 (d, J = 8 Hz, 1H,
H5), 7.49 (dd, J = 8, 8 Hz, 1H, H7), 7.27 (dd, J = 8, 8 Hz, 1H, H6), 6.91
(br, s (AB → A2) 2H, H14, H15), 6.79 (d, J = 9 Hz, 1H, H3), 2.32 (s, 3H,
(PPh3). H NMR ((CD3)2SO; 400 MHz, δ, ppm): 9.75 (d, J = 18 Hz,
1
1H, H11), 8.79 (d, J = 8 Hz, 1H, H5), 8.52 (s, 1H, H17), 7.75–7.70 (m,
8H, PPh3 ortho Hs, H4, H8), 7.64–7.56 (m, 10H, PPh3 meta/para Hs,
H7), 7.34 (dd, J = 8, 8 Hz, 1H, H6), 7.04 (d, J = 9 Hz, 1H, H15), 6.74
(d, J = 9 Hz, 1H, H3), 6.60 (d, J = 9 Hz, 1H, H14), 2.29 (s, 3H, Me). 13
C
NMR ((CD3)2SO; 100 MHz, δ, ppm): 167.58 (C13), 167.55 (C2), 163.53
(C11), 142.62 (C12), 139.36 (C9), 134.54 (d, 2JC,P = 14 Hz, Co. of PPh3),
4
131.97 (C16), 131.84 (d, JC,P = 6 Hz, Cp of PPh3), 129.29 (d,
3JC,P = 6 Hz, Cm of PPh3), 129.14 (C17), 128.95 (d, 1JC,P = 27 Hz, Ci
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Appl. Organometal. Chem. (2016)