2-(2-Methoxynaphthalen-1-yl)-4,4,5,5-tetramethyl-1,3,2-dioxa-
borolane (2s). 1H NMR (300 MHz, CDCl3): δ 1.48 (s, 12H),
3.92 (s, 3H), 7.21 (d, J = 9.0 Hz, 1H), 7.26–7.33 (m, 1H),
7.41–7.46 (m, 1H), 7.76 (d, J = 8.1 Hz, 1H), 7.85 (d, J = 9.0
Hz, 1H), 7.93 (d, J = 8.4 Hz, 1H). 13C NMR (75 MHz, CDCl3):
δ 25.0, 56.8, 84.1, 113.1, 123.4, 126.7, 126.9, 128.3, 129.1,
131.8, 137.2, 161.6. HRMS calcd for C17H21BO3 [M + H]+:
285.1662, found 285.1660.
3′-Methylbiphenyl-4-carbaldehyde
(5a)21. 1H
NMR
(300 MHz, CDCl3): δ 2.36 (s, 3H), 7.14–7.17 (m, 1H),
7.29–7.36 (m, 3H), 7.65 (d, J = 8.2 Hz, 2H), 7.85 (d, J = 8.2
Hz, 2H), 9.96 (s, 1H). 13C NMR (75 MHz, CDCl3): δ 21.6,
124.6, 127.8, 128.2, 129.1, 129.4, 130.3, 135.3, 138.8, 139.8,
147.5, 192.1.
3′-Methylbiphenyl-4-carbonitrile (5b)13. 1H NMR (300 MHz,
CDCl3): δ 2.35 (s, 3H), 7.31–7.17 (m, 4H), 7.57–7.64 (m, 4H).
13C NMR (75 MHz, CDCl3): δ 21.6, 110.9, 119.1, 124.5, 127.9,
128.1, 129.1, 129.5, 132.7, 138.9, 139.3, 145.9.
2-Benzyl-4,4,5,5-tetramethyl-1,3,2-dioxaboralane (4a)18. 1H
NMR (300 MHz, CDCl3): δ 1.18 (s, 12H), 2.21 (s, 2H),
7.01–7.18 (m, 5H). 13C NMR (75 MHz, CDCl3): δ 24.8, 83.5,
124.9, 128.4, 129.1, 138.8.
1-(4′-Methylbiphenyl-4-yl)ethanone
(5c)22. 1H
NMR
(300 MHz, CDCl3): δ 2.41 (s, 3H), 2.63 (s, 3H), 7.28 (d, J =
7.9, 2H), 7.53 (d, J = 8.1, 2H), 7.67 (d, J = 8.4 Hz, 2H), 8.01
(d, J = 8.4, 2H). 13C NMR (75 MHz, CDCl3): δ 21.3, 26.8,
127.1, 127.2, 129.1, 129.8, 135.8, 137.1, 138.4, 145.9, 197.9.
2-(4-Fluorobenzyl)-4,4,5,5-tetramethyl-1,3,2-dioxaboralane
(4b). 1H NMR (300 MHz, CDCl3): δ 1.25 (s, 12H), 2.27
(s, 2H), 6.90–6.96 (m, 2H), 7.12–7.16 (m, 2H). 13C NMR
(75 MHz, CDCl3): δ 24.9, 83.6, 115.1 (d, J = 35 Hz), 130.3
(d, J = 12.62 Hz), 134.3 (d, J = 5.37 Hz), 160.9 (d, J = 400.75
Hz). HRMS calcd for C13H18BFO2K [M + K]+ 275.1021, found
275.1025.
1-(3′-Methylbiphenyl-4-yl)ethanone
(5d)13. 1H
NMR
(300 MHz, CDCl3): δ 2.44 (s, 3H), 2.63 (s, 3H), 7.21–7.26
(m, 1H), 7.33–7.44 (m, 3H), 7.68 (d, J = 8.4 Hz, 2H), 8.03 (d, J
= 8.4 Hz, 2H). 13C NMR (75 MHz, CDCl3): δ 21.6, 26.7, 124.5,
127.3, 128.1, 128.9, 129.1, 135.9, 138.7, 139.9, 146.0, 197.8.
2-(3-Chlorobenzyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
(4c)19. 1H NMR (300 MHz, CDCl3): δ 1.14 (s, 12H), 2.17
(s, 2H), 6.95–7.17 (m, 4H). 13C NMR (75 MHz, CDCl3): δ 24.8,
83.7, 125.2, 127.3, 129.2, 129.5, 134.1, 140.9.
3-Methoxy-4′-methylbiphenyl (5e)22. 1H NMR (300 MHz,
CDCl3): δ 2.32 (s, 3H), 3.79 (s, 3H), 6.85 (dd, J = 9.0 Hz, J =
2.3 Hz, 1H), 7.11–7.04 (m, 2H), 7.16–7.18 (m, 2H), 7.27 (t, J =
7.83 Hz, 1H), 7.42 (d, J = 8.1 Hz, 2H). 13C NMR (75 MHz,
CDCl3): δ 21.2, 55.4, 112.5, 112.9, 119.7, 127.2, 129.6, 129.8,
137.3, 138.4, 142.9, 160.1.
2-(2-Chlorobenzyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
(4d). 1H NMR (300 MHz, CDCl3): δ 1.24 (s, 12 H), 2.38
(s, 2H), 7.07–7.14 (m, 2H), 7.21–7.32 (m, 2H). 13C NMR
(75 MHz, CDCl3): δ 24.9, 83.7, 126.6, 126.8, 129.1, 130.9,
134.0, 137.7. HRMS calcd for C13H18BClO2Na [M + Na]+
275.0986, found 275.0989.
1-(4-(4-Methylnaphthalen-1-yl)phenyl)ethanone
(5f). 1H
NMR (300 MHz, CDCl3): δ 2.6 (s, 3H), 2.7 (s, 3H), 7.24 (d, J =
7.2 Hz, 1H), 7.32 (d, J = 7.2 Hz, 1H), 7.40–7.48 (m, 1H), 7.51
(d, J = 8.3 Hz, 3H), 7.79 (d, J = 8.4 Hz, 1H), 7.99 (d, J = 8.3
Hz, 3H), 13C NMR (75 MHz, CDCl3): δ 19.7, 26.8, 124.6,
125.9, 126.1, 126.2, 126.3, 126.7, 128.4, 130.5, 131.3, 132.9,
134.8, 135.9, 137.5, 146.2, 197.9. HRMS calcd for C19H16ONa
[M + Na]+ 283.1099, found 283.1098.
4,4,5,5-Tetramethyl-2-(2-methylbenzyl)-1,3,2-dioxaborolane
(4e)18. 1H NMR (300 MHz, CDCl3): δ 1.23 (s, 12H), 2.26
(s, 3H), 2.28 (s, 3H), 7.04–7.15 (m, 4H). 13C NMR (75 MHz,
CDCl3): δ 20.2, 24.8, 83.5, 125.3, 125.9, 129.6, 129.9, 136.1,
137.7.
4-Benzyl-acetophenone (5g)8c. 1H NMR (300 MHz, CDCl3):
δ 2.51 (s, 3H), 3.98 (s, 2H), 7.12–7.19 (m, 3H), 7.21–7.28
(m, 4H), 7.83 (d, J = 8.3 Hz, 2H), 13C NMR (75 MHz, CDCl3):
δ 26.6, 41.9, 126.5, 128.7, 128.9, 129.2, 135.3, 140.1, 146.9,
197.8.
4,4,5,5-Tetramethyl-2-(napthalen-1-ylmethyl)-1,3,2-dioxaboro-
lane (4f)20. 1H NMR (300 MHz, CDCl3): δ 1.21 (s, 12H), 2.71
(s, 2H), 7.37–7.39 (m, 2H), 7.46–7.51 (m, 2H), 7.67 (d, J = 6.9
Hz, 1H), 7.84 (dd, J = 6.23 Hz, J = 1.67 Hz, 1H), 8.03 (d, J =
7.32 Hz, 1H). 13C NMR (75 MHz, CDCl3): δ 24.8, 83.7, 124.7,
125.5, 125.52, 125.9, 126.6, 128.7, 132.6, 133.9, 135.8.
1-Benzyl-4-methoxybenzene (5h)8c. 1H NMR (300 MHz,
CDCl3): δ 3.81 (s, 3H), 3.93 (s, 2H), 6.79–6.86 (m, 2H),
7.07–7.12 (m, 2H), 7.16–7.20 (m, 3H), 7.26–7.30 (m, 2H). 13C
NMR (75 MHz, CDCl3): δ 41.4, 55.6, 114.3, 126.4, 128.8,
129.2, 129.8, 130.3, 133.6, 158.4.
General procedure for Pd nanoparticle catalyzed one pot two
step for the synthesis for unsymmetrical biaryls and diaryl-
methane. Miyaura borylation procedure was followed for the
specified time. The reaction mixture was cooled to room temp-
erature and then K2PdCl4 (10 mg, 0.03 mmol), aryl halide
(1 mmol) or benzyl halide (1 mmol), and CsF (304 mg,
2 mmol) was added and the reaction mixture was stirred at 70 °C
for the specified time. Then the reaction mixture was allowed to
cool at room temperature, extracted with ethyl acetate and the
organic layers were dried over anhydrous Na2SO4 and concen-
trated in vacuo. The residue thus obtained was purified by flash
column chromatography on silica gel (230 ∼ 400 mesh) with a
mixture of ethyl acetate and petroleum ether (2–10%) as eluent.
General procedure for Pd nanoparticle catalyzed synthesis of
symmetrical biaryls
Weighed amount of K2PdCl4 (20 mg, 6 mol%) and PEG 600
(1 g, 1.66 mol) was heated at 70 °C for 15 min to form the
Pd nanoparticle. Then it was cooled and to this suspension of
colloidal Pd, bis(pinacolato)diboron (254 mg, 1.0 mmol), aryl
bromide (2 mmol) and CsF (608 mg, 4 mmol) were added and
stirred at 70 °C for the specified time. Then the reaction mixture
666 | Green Chem., 2012, 14, 661–667
This journal is © The Royal Society of Chemistry 2012