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mmol), phenylboronic acid (1.2 mmol), NaBH4 (0.005 g, 0.1
mmol), K2CO3 (0.21 g, 1.5 mmol) and PPh3 (0.0026 g, 0.1 mmol)
were added into the ask and the mixture was stirred for
appropriate time, under N2 atmosphere. Aer completion of the
reaction, catalyst was magnetically separated and the desired
product was puried via FCC method.
3.2. Methods
3.2.1. Preparation of VPMP micro-plates. The purchased
pumice powder (5.0 g) was placed into the milling bowl and
grinded via ball-milling (50 Hz), for 1 h. Then, the grinded
pumice was transferred to a crucible (50 mL) and the calcina-
tion process was carried out at 400 ꢂC, for 6 h. Aer completion
of the calcination process and cooling down to room tempera-
ture, 2.0 g of the pumice was placed into a glass round bottom
ask (50 mL) and dispersed in the as-prepared HCl solution
(0.1 M, 20 mL) via ultrasonication by using a cleaner bath (30
KHz, 200 W Lꢀ1), at room temperature. Next, the mixture was
stirred for 12 h at the same conditions. Ultimately, the VPMP
particles were magnetically collected and washed with ꢂdeion-
ized water for several times, and then dried in oven (60 C) for
24 h.
3.2.2. Preparation of VPMP@CLS composite. In a glass
round bottom ask (100 mL), 0.01 g of CLS powder was placed
and deionized water (20 mL) was added and well mixed via
stirring at room temperature until a clear colorless solution was
obtained. Aerward, VPMP (1.0 g) was added and dispersed,
and then stirring was continued for 6 h, under the same
conditions. Aer completion, the prepared magnetic
VPMP@CLS particles were collected, washed with deionized
water, and dried (as explained in the previous section).
3.2.3. Preparation of VPMP@CLS-Pd(II) composite
3.2.6. Spectral data
Biphenyl (a). 1H NMR (500 MHz, DMSO, d, ppm): 7.34 (2H, t, J
¼ 7.4 Hz, H-Ar), 7.44 (4H, t, J ¼ 7.8 Hz, H-Ar), 7.62 (4H, d, J ¼
7.3 Hz, H-Ar).
4-Carbaldehyde-biphenyl (b). 1H NMR (500 MHz, DMSO, d,
ppm): 7.40–7.52 (3H, m, H-Ar), 7.75 (2H, d, J ¼ 7.6 Hz, H-Ar),
7.86 (2H, d, J ¼ 6.8 Hz, H-Ar), 7.98 (2H, d, J ¼ 6.8 Hz, H-Ar),
10.05 (1H, s, CHO).
1
4-Methanol-biphenyl (c). H NMR (500 MHz, DMSO, d, ppm):
4.54 (2H, d, J ¼ 9.4 Hz, CH2), 5.24 (H, t, J ¼ 9.5 Hz, OH), 7.31–
7046 (5H, m, H-Ar), 7.59–7.65 (4H, m, H-Ar).
4-Methyl-biphenyl (d). 1H NMR (500 MHz, CDCl3, TMS): d 7.58
(d, 2H, J ¼ 7.5 Hz), 7.49 (d, 2H, J ¼ 8.0 Hz), 7.43 (t, 2H, J ¼ 7.5
Hz), 7.32 (t, 1H, J ¼ 7.3 Hz), 7.25 (d, 2H, J ¼ 7.5 Hz).
4-Methoxy-biphenyl (e). 1H NMR (500 MHz, CDCl3, TMS):
d 7.54 (q, 4H, J ¼ 6.7 Hz), 7.42 (t, 2H, J ¼ 7.7 Hz), 7.28 (t, 1H, J ¼
14.8 Hz), 6.98 (d, 2H, J ¼ 4.3 Hz), 3.86 (s, 3H).
1
4-Nitro-biphenyl (f). H NMR (500 MHz, CDCl3, TMS): d 8.32
(d, 2H, J ¼ 9.0 Hz), 7.75 (d, 2H, J ¼ 9.0 Hz), 7.64 (d, 2H, J ¼ 7.0
Hz), 7.51 (t, 2H, J ¼ 7.5 Hz), 7.46 (t, 1H, J ¼ 7.2 Hz).
1-Biphenyl-4-yl-ethanone (g). 1H NMR (500 MHz, CDCl3, TMS):
d 8.03 (d, 2H, J ¼ 8.4 Hz), 7.69 (d, 2H, J ¼ 4.0 Hz), 7.63 (t, 2H, J ¼
4.5 Hz), 7.48 (t, 2H, J ¼ 7.5 Hz), 7.40 (t, 1H, J ¼ 7.0 Hz), 2.64 (s,
3H).
3.2.3.1 Solution A. A solution of PdCl2 (0.1 M, in HCl solu-
tion) was prepared. For this purpose, in a glass round bottom
ask (25 mL), brown powder of PdCl2 salt was dissolved in
ꢂ
deionized water that was heated to around 60 C, and the pH
value was reduced to ꢁ3 by addition of two drops (0.1 mL) of the
concentrate HCl. Aer forming a red clear solution, it was
cooled down to room temperature.
3.2.3.2 Mixture A. In a glass round bottom ask (100 mL),
VPMP@CLS particles (0.5 g) were dispersed in deionized water
(10 mL) via ultrasonication, and the as-prepared solution of
KOH (1.0 M, 2.0 mL) was added drop by drop, during the
ultrasonication at room temperature.
Finally, solution A was dropwise added to the content of
mixture A, during the stirring at room temperature. Aer
completion of the addition, the mixture was stirred for addi-
tional 12 h, at the same conditions. Separation and purication
was carried out as explained at the end of the previous sections.
3.2.4. Preparation of VPMP@CLS-Pd(0) composite. In
a round bottom ask (50 mL), VPMP@CLS-Pd(II) particles (0.1 g)
was placed and dispersed in DMSO (5.0 mL) via ultrasonication.
Then, the pH of the mixture was tuned at ca. 8.0 by addition of
K2CO3 (0.4 g). Next, NaBH4 (0.05 g, 1.0 mmol) and PPh3 (0.026 g,
1.0 mmol) were added into the ask and the mixture was stirred
for 30 min, under N2 atmosphere at room temperature. Finally,
the particles were magnetically separated, washed and dried in
a vacuum oven.
1
Biphenyl-4-carbonitrile (h). H NMR (500 MHz, CDCl3, TMS):
d 7.73 (d, 2H, J ¼ 8.5 Hz), 7.68 (d, 2H, J ¼ 8.5 Hz), 7.59 (t, 2H, J ¼
4.5 Hz), 7.48 (t, 2H, J ¼ 7.5 Hz), 7.42 (m, 1H).
2-Methyl-biphenyl (i). 1H NMR (500 MHz, CDCl3, TMS): d 7.42
(t, 2H, J ¼ 7.5 Hz), 7.34 (m, 3H), 7.26 (m, 4H), 2.28 (s, 3H).
1
Biphenyl-3-ol (j). H NMR (500 MHz, CDCl3, TMS): d 7.56 (d,
2H, J ¼ 7.7 Hz), 7.43 (t, 2H, J ¼ 7.6 Hz), 7.34 (m, 2H), 7.17 (d, 1H,
J ¼ 7.7 Hz), 7.06 (s, 1H), 6.82 (m, 1H), 4.82 (s, 1H).
4. Conclusion
An efficient heterogeneous catalytic system based on the prin-
ciples of green chemistry has been presented and suitably
applied in the synthetic reactions of biphenyl pharmaceutical
compounds. In summary, volcanic pumice magnetic particles
(VPMP) in micro scale have been constructively composed with
cellulose (CLS) natural polymeric strands. Briey, two aims were
pursued by this composition: (rst) inherent magnetic property
of VPMP that provides a great possibility to isolate the catalyst
particles with high convenience, (second) high heterogeneity
and structural stability is obtained by the VPMP that results in
signicant recyclability for the catalyst. Moreover, palladium
nanoparticles (Pd NPs) have been incorporated to the structure
as the main catalytic sites. For the synthetic reactions of the
biphenyl pharmaceutical derivatives (via Suzuki approach), the
present Pd(II) NPs onto the surfaces were reduced to Pd(0). In
this regard, a plausible mechanism has been suggested in the
3.2.5. General procedure for the synthesis of biphenyl
derivatives by VPMP@CLS-Pd catalytic system (in situ reduction
of Pd2+). In a round bottom ask (100 mL), the VPMP@CLS-
Pd(II) particles (0.01) were dispersed in DMSO (5.0 mL) via
ultrasonication, at room temperature. Then, aryl halide (1.0
23368 | RSC Adv., 2020, 10, 23359–23371
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