Organic & Biomolecular Chemistry
Page 6 of 9
DOI: 10.1039/C4OB02343A
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washed with saturated NaHCO3 (30 mL ×2) and saturated NaCl
(30 mL×1) respectively, dried over Na2SO4. The solution was
concentrated in vacuo and purified by column chromatography on
silica gel (eluting with 3:1 to 1:1 petroleum ether/ethyl acetate) to
give the desired product (see Supporting Information).
6H); 13C NMR (100 MHz, DMSOꢀd6) δ: 165.9, 154.6, 140.2,
132.8, 131.8, 128.5, 127.4, 120.3, 114.3, 55.3; HRMS (ESI)
calcd. for C21H19N2O3 [MꢀH]ꢀ: 347.1401, found: 347.1409.
N',N'-bis(3-Methoxyphenyl)benzohydrazide (2h). White solid;
mp: 167ꢀ168 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.25 (s, 1H),
7.88ꢀ7.82 (m, 2H), 7.56 (t, J = 7.4 Hz, 1H), 7.46 (t, J = 7.6 Hz,
2H), 7.19 (t, J = 8.1 Hz, 2H), 6.84ꢀ6.78 (m, 4H), 6.59 (dd, J = 8.2,
1.7 Hz, 2H), 3.75 (s, 6H); 13C NMR (100 MHz, CDCl3) δ: 166.4,
160.5, 147.1, 132.5, 132.3, 129.9, 128.8, 127.3, 112.2, 108.6,
105.9, 55.3. HRMS (ESI) calcd. for C21H19N2O3 [MꢀH]ꢀ:
347.1401, found: 347.1398.
Typical procedure for the Cu(II)-catalyzed homocoupling of
N’-aryl acylhydrazines: A mixture of aryl acylhydrazine (0.3
mmol), Cu(OAc)2·H2O (0.03 mmol), 1,10ꢀPhen·H2O (0.06 mmol)
and TEA (0.60 mmol) in MeOH (2.0 mL) was stirred at ambient
temperature for 12ꢀ24 h. After completion of the reaction
(indicated by TLC), the mixture was quenched with saturated
NaCl solution, extracted by EtOAc, and dried over Na2SO4. The
crude product was purified by flash column chromatography to
provide the corresponding product 2aꢀad.
N',N'-bis(2-Methoxyphenyl)benzohydrazide (2i). Offꢀwhite
1
solid; mp: 178ꢀ179 ℃; H NMR (400 MHz, CDCl3) δ: 8.58 (s,
1H), 7.82ꢀ7.76 (m, 2H), 7.51 (t, J = 7.3 Hz, 1H), 7.43 (t, J = 7.5
Hz, 2H), 7.18 (d, J = 8.1 Hz, 2H), 7.07 (dd, J = 11.0, 4.5 Hz, 2H),
6.89 (t, J = 7.4 Hz, 4H), 3.75 (s, 6H); 13C NMR (100 MHz,
CDCl3) δ: 167.0, 152.3, 136.0, 133.6, 131.7, 128.66, 127.2, 125.0,
123.4, 120.9, 112.1, 55.8; HRMS (ESI) calcd. for C21H19N2O3 [Mꢀ
H]ꢀ: 347.1401, found: 347.1410.
N',N'-diPhenylbenzohydrazide (2a). White solid; mp: 159ꢀ160
1
℃; H NMR (400 MHz, CDCl3) δ: 8.36 (s, 1H), 7.88ꢀ7.83 (m,
2H), 7.58ꢀ7.53 (m, 1H), 7.46 (t, J = 7.6 Hz, 2H), 7.32ꢀ7.27 (m,
4H), 7.21 (dd, J = 8.7, 1.1 Hz, 4H), 7.03 (dd, J = 10.3, 4.2 Hz,
2H); 13C NMR (100 MHz, CDCl3) δ: 166.5, 145.8, 132.5, 132.2,
129.2, 128.8, 127.3, 123.0, 119.5; HRMS (ESI) calcd. for
C19H17N2O [M+H]+: 289.1335, found: 289.1325.
N',N'-bis(4-Fluorophenyl)benzohydrazide (2b). White solid;
mp: 172ꢀ173 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.36 (s, 1H),
7.85ꢀ7.79 (m, 2H), 7.57 (t, J = 7.4 Hz, 1H), 7.46 (t, J = 7.6 Hz,
2H), 7.15ꢀ7.07 (m, 4H), 7.02ꢀ6.93 (m, 4H); 13C NMR (100 MHz,
CDCl3) δ: 166.5, 160.2, 157.7, 142.3, 132.4, 132.2, 128.9, 127.2,
121.2, 121.2, 116.1, 115.8; HRMS (ESI) calcd. for C19H13F2N2O
[MꢀH]ꢀ: 323.1001, found: 323.1005.
N',N'-bis(4-Chlorophenyl)benzohydrazide (2c). Offꢀwhite solid;
mp: 208ꢀ209 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.38 (s, 1H),
7.82 (d, J = 7.3 Hz, 2H), 7.58 (t, J = 7.4 Hz, 1H), 7.47 (t, J = 7.6
Hz, 2H), 7.27ꢀ7.22 (m, 4H), 7.10 (d, J = 8.8 Hz, 4H); 13C NMR
(100 MHz, CDCl3) δ: 166.6, 144.1, 132.6, 131.9, 129.3, 128.9,
128.3, 127.3, 120.7; HRMS (ESI) calcd. for C19H15Cl2N2O
[M+H]+: 357.0556, found: 357.0545.
N',N'-bis(4-Bromophenyl)benzohydrazide (2d). Offꢀwhite solid;
mp: 216ꢀ217 ℃; 1H NMR (400 MHz, DMSOꢀd6) δ: 11.32 (s, 1H),
7.97ꢀ7.88 (m, 2H), 7.62 (t, J = 7.4 Hz, 1H), 7.53 (t, J = 7.5 Hz,
2H), 7.50ꢀ7.43 (m, 4H), 7.16ꢀ7.07 (m, 4H); 13C NMR (100 MHz,
DMSOꢀd6) δ: 166.2, 145.2, 132.7, 132.6, 132.4, 129.1, 128.0,
121.3, 114.4; HRMS (ESI) calcd. for C19H13Br2N2O [MꢀH]ꢀ:
442.9400, found: 442.9420.
N',N'-bis(4-(triFluoromethoxy)phenyl)benzohydrazide
(2j).
White solid; mp: 163ꢀ164 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.48
(s, 1H), 7.86ꢀ7.80 (m, 2H), 7.58 (t, J = 7.5 Hz, 1H), 7.46 (t, J =
7.7 Hz, 2H), 7.19ꢀ7.11 (m, 8H); 13C NMR (100 MHz, CDCl3) δ:
166.7, 144.8, 144.2, 132.7, 131.9, 128.9, 127.3, 122.1, 121.8,
120.6, 119.3; HRMS (ESI) calcd. for C21H13F6N2O3 [MꢀH]ꢀ:
455.0836, found: 455.0827.
N',N'-bis(4-(Methylsulfonyl)phenyl)benzohydrazide
(2k).
Brown solid; mp: 240ꢀ241 ℃; 1H NMR (400 MHz, DMSOꢀd6) δ:
11.63 (s, 1H), 8.00ꢀ7.96 (m, 2H), 7.90ꢀ7.86 (m, 4H), 7.68ꢀ7.63
(m, 1H), 7.57 (t, J = 7.5 Hz, 2H), 7.47ꢀ7.42 (m, 4H), 3.19 (s, 6H);
13C NMR (100 MHz, DMSOꢀd6) δ: 165.7, 148.6, 134.4, 132.5,
131.6, 127.8, 128.7, 127.6, 118.8, 43.8; HRMS (ESI) calcd. for
C21H19N2O5S2 [MꢀH]ꢀ: 443.0741, found: 443.0741.
N',N'-bis(4-Nitrophenyl)benzohydrazide (2l). Yellow solid;
mp: 287ꢀ288 ℃; 1H NMR (400 MHz, DMSOꢀd6) δ: 11.82 (s, 1H),
8.24 (d, J = 9.2 Hz, 4H), 7.98 (d, J = 7.2 Hz, 2H), 7.66 (d, J = 7.3
Hz, 1H), 7.58 (t, J = 7.5 Hz, 2H), 7.47 (d, J = 9.2 Hz, 4H); 13C
NMR (100 MHz, DMSOꢀd6) δ: 165.7, 149.7, 142.3, 132.6, 131.4,
128.8, 127.6, 125.5, 119.1; HRMS (ESI) calcd. for C19H13N4O5
[MꢀH]ꢀ: 377.0891, found: 377.0898.
N',N'-dip-Tolylbenzohydrazide (2m). White solid; mp: 190ꢀ191
1
℃; H NMR (400 MHz, CDCl3) δ: 8.21 (s, 1H), 7.86ꢀ7.82 (m,
2H), 7.55 (t, J = 7.4 Hz, 1H), 7.45 (t, J = 7.5 Hz, 2H), 7.08 (s,
8H), 2.30 (s, 6H); 13C NMR (100 MHz, CDCl3) δ: 166.4, 143.9,
132.7, 132.4, 132.1, 129.8, 128.8, 127.3, 119.6, 20.7; HRMS
(ESI) calcd. for C21H19N2O [MꢀH]ꢀ: 315.1503, found: 315.1504.
N',N'-dim-Tolylbenzohydrazide (2n).White solid; mp: 173ꢀ
N',N'-bis(3-Chlorophenyl)benzohydrazide (2e). Light brown
1
solid; mp: 158ꢀ159 ℃; H NMR (400 MHz, CDCl3) δ: 8.59 (s,
1H), 7.82 (d, J = 7.3 Hz, 2H), 7.57 (t, J = 7.4 Hz, 1H), 7.45 (t, J =
7.7 Hz, 2H), 7.22ꢀ7.13 (m, 4H), 7.08ꢀ6.99 (m, 4H); 13C NMR
(100 MHz, CDCl3) δ: 166.7, 146.4, 135.0, 132.6, 131.8, 130.3,
128.9, 127.3, 123.5, 119.6, 117.7; HRMS (ESI) calcd. for
C19H13Cl2N2O [MꢀH]ꢀ: 355.0410, found: 355.0418.
N',N'-bis(2-Chlorophenyl)benzohydrazide (2f). White solid;
mp: 211ꢀ212 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.74 (s, 1H),
7.86ꢀ7.81 (m, 2H), 7.58ꢀ7.52 (m, 1H), 7.46 (t, J = 7.5 Hz, 2H),
7.36 (td, J = 7.9, 1.4 Hz, 4H), 7.22 (td, J = 7.8, 1.5 Hz, 2H), 7.08
(td, J = 7.8, 1.5 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 167.1,
143.3, 132.3, 130.6, 128.8, 127.9, 127.4, 125.8, 125.2; HRMS
(ESI) calcd. for C19H13Cl2N2O [MꢀH]ꢀ: 355.0410, found:
355.0408.
1
174 ℃; H NMR (400 MHz, CDCl3) δ: 8.21 (s, 1H), 7.86 (d, J =
7.3 Hz, 2H), 7.56 (t, J = 7.4 Hz, 1H), 7.47 (t, J = 7.5 Hz, 2H),
7.17 (t, J = 7.7 Hz, 2H), 7.05ꢀ6.98 (m, 4H), 6.86 (d, J = 7.5 Hz,
2H), 2.30 (s, 6H); 13C NMR (100 MHz, CDCl3) δ: 166.4, 146.0,
139.1, 132.7, 132.2, 129.0, 128.8, 127.3, 123.9, 120.3, 116.8, 21.6;
HRMS (ESI) calcd. for C21H19N2O [MꢀH]ꢀ: 315.1503, found:
315.1515.
N',N'-dio-Tolylbenzohydrazide (2o). White solid; mp: 213ꢀ214
1
℃; H NMR (400 MHz, CDCl3) δ: 7.99 (s, 1H), 7.79 (d, J = 7.3
Hz, 2H), 7.52 (d, J = 7.5 Hz, 1H), 7.44 (t, J = 7.6 Hz, 2H), 7.19
(d, J = 7.2 Hz, 2H), 7.13 (t, J = 7.0 Hz, 2H), 7.05 (t, J = 7.0 Hz,
4H), 2.18 (s, 6H); 13C NMR (100 MHz, CDCl3) δ: 165.0, 145.8,
132.9, 132.6, 131.9, 131.6, 128.8, 127.1, 126.5, 124.7, 121.5,
18.6; HRMS (ESI) calcd. for C21H19N2O [MꢀH]ꢀ: 315.1503,
found: 315.1517.
N',N'-bis(4-Methoxyphenyl)benzohydrazide (2g). White solid;
mp: 212ꢀ213 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.18 (s, 1H),
7.83 (d, J = 7.4 Hz, 2H), 7.58ꢀ7.52 (m, 1H), 7.46 (t, J = 7.5 Hz,
2H), 7.11 (d, J = 8.9 Hz, 4H), 6.83 (d, J = 8.9 Hz, 4H), 3.78 (s,
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