486
Nooredin Goudarzian et al.
1.5), 7.36–7.43 (m, 3H); 13C NMR (62.9 MHz,
2. Experimental
2.1 General remarks
CDCl3)δ (ppm): 147.6, 147.0, 138.7, 129.1, 128.9,
127.7, 127.3, 124.1.
1
1d60: H NMR (250 MHz, CDCl3)δ (ppm): 7.73 (m,
NMR spectra were recorded on a Bruker Avance DPX-
250. The purity of the products and the progress of
the reactions were accomplished by TLC on silica–gel
polygram SILG/UV254 plates or GC analysis using a
3-meter length column packed with DC-200 stationary
phase.
2H), 7.39–7.59 (m, 7H), 2.43 (s, 3H); 13C NMR
(62.9 MHz, CDCl3)δ (ppm): 142.0, 141.3, 135, 130.4,
129.9, 129.3, 128.9, 128.2, 127.6, 126.4, 125.9, 20.6.
1
1e61: H NMR (250 MHz, CDCl3)δ (ppm): 7.53–7.49
(m, 2H). 7.26–7.14 (m, 5H), 6.96–6.86 (m, 1H).
1
1f60: H NMR (250 MHz, CDCl3)δ (ppm): 8.07–7.95
(m, 3H), 7.61–7.53 (m, 9H); 13C NMR (62.9 MHz,
CDCl3)δ (ppm): 140.9, 140.4, 133.9, 131.7 129.8,
128.8, 128.4, 127.4, 127.3, 127.0, 126.7, 126.1, 125.9,
125.5.
2.2 General experimental procedure for the
Suzuki–Miyaura reaction
1
1g60: H NMR (250 MHz, CDCl3)δ (ppm): 7.73 (m,
In 5 mL flask containing ethylene glycol (2 mL), was
added polyethyleneimine (300 mg) and stirred until
solving in 80 or 100◦C. To the resulting solution were
added NiCl2.6H2O (1 mol%) aryl halide (1 mmol),
phenylboronic acid or Potassium phenyltrifluoroborate
(1.5 mmol) and K2CO3 (1.5 mmol). The progress of
the reaction was monitored by TLC or GC analyses.
After completion of the reaction, the reaction mixture
was allowed to cool down to room temperature and
extracted with ethyl acetate or diethyl ether (3 × 2 mL)
and the upper organic phase was separated, washed
with 3 mL water, dried over anhydrous MgSO4 and
evaporated. Further purification was performed by col-
umn chromatography (EtOAc/n-hexane) to obtain the
desired coupling product.57–59
2H), 7.59–7.39 (m, 7H), 2.43 (s, 3H).
1h: 1H NMR (250 MHz, CDCl3)δ (ppm): 7.50–7.18 (m,
7H), 6.85–6.81(m, 2H), 4.61 (s, 1H).
1i62: 1H NMR (250 MHz, CDCl3)δ (ppm): 8.85 (s, 1 H),
8.57 (s, 1H), 7.84 (d, 1 H, J = 8.0), 7.33–7.57 (m, 6 H);
13C NMR (62.9 MHz, CDCl3)δ (ppm): 148.3, 148.1,
137.7, 136.7, 134.4, 129.0, 128.1, 127.1, 123.6.
1
1j62: H NMR (250 MHz, CDCl3)δ (ppm): 7.45–7.75
(m, 9 H); 13C NMR (62.9 MHz, CDCl3)δ (ppm): 141.8,
136.2, 132.4, 128.6, 126.9, 119.0, 110.5.
1
1k60: H NMR (250 MHz, CDCl3)δ (ppm): 7.29–7.50
(m, 9 H); 13C NMR (62.9 MHz, CDCl3)δ (ppm): 139.1,
138.4, 133.7, 129.0, 128.7, 128.3, 127.5, 126.9.
3. Results and discussion
2.3 Recycling of the catalyst
Polyethyleneimine has been produced on the indus-
trial scale since 1938 which is obtained mainly by the
polymerization of aziridine63 (figure 1).
After completion of the reaction of iodobenzene
(1 mmol) with phenylboranic acid (1.5 mmol), the reac-
tion mixture was cooled down to room temperature and
washed with diethyl ether (3 × 2 mL) to extract prod-
uct and unreacted material. Then residue containing of
polymer and NiCl2. 6H2O was reused for the similar
reaction.
In this article, we report using of polyethyleneimine
(PEI) as ligand in the presence of NiCl2·6H2O for the
successful recyclable Suzuki–Miyaura coupling reac-
tion in ethylene glycol under phosphine-free and mild
reaction conditions. Polyethyleneimine is stable, cheap,
non-toxic polymer, and its handling in the presence of
NiCl2·6H2O for Suzuki coupling does not need special
precautions and inert atmosphere.
2.4 Characterization data of compounds
Optimized reaction conditions were achieved by the
reaction of 4-iodoanisole (1 mmol) as a model com-
pound with phenylboranic acid (1.5 mmol) in the pres-
ence of NiCl2. 6H2O (1 mol%), polyethyleneimine
1
1a60: H NMR (250 MHz, CDCl3)δ (ppm): 7.33–7.64
(m, 10 H).
1
1b60: H NMR (250 MHz, CDCl3)δ (ppm): 7.51–7.57
(m, 4H), 7.41 (t, 1H, J = 7.2), 7.28 (t, 1H, J = 7.2), 6.98
(d, 2H, J = 7.5), 3.85 (s, 3H); 13C NMR (62.9 MHz,
CDCl3)δ (ppm): 159.2, 140.9, 133.8, 128.8, 128.4,
128.2, 127.1, 114.3, 55.3.
N
n
H
1c60: 1H NMR (250 MHz, CDCl3)δ (ppm): 8.19 (d, 2H,
J = 9.0), 7.63 (d, 2H, J = 9.0), 7.53 (dd, 2 H, J = 7.5,
Figure 1. Polyethyleneimine.