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PAPER
1H NMR (400 MHz, CDCl3): d = 7.62 (d, J = 2.01 Hz, 1 H, ArH),
7.46 (d, J = 8.97 Hz, 2 H, ArH), 7.35 (dd, J = 8.51 Hz, 1 H, ArH),
6.90 (d, J = 8.97 Hz, 2 H, ArH), 6.71 (d, J = 8.42 Hz, 1 H, ArH),
4.78 (s, 2 H, NH2), 3.84 (s, 3 H, OCH3).
1H NMR (400 MHz, CDCl3): d = 7.23–7.41 (m, 5 H, ArH), 6.88 (d,
J = 16.29 Hz, 1 H, alkenyl H), 6.19 (dd, J = 2.20, 16.29 Hz, 1 H,
alkenyl H), 2.75–2.99 (m, 1 H, alkyl H), 1.91–2.06 (m, 3 H, alkyl
H), 1.45–1.86 (m, 5 H, alkyl H).
13C NMR (100 MHz, CDCl3): d = 160.2, 150.9, 136.2, 133.2, 133.0,
114.4, 114.2, 114.0, 108.7, 100.2, 96.4, 82.1, 55.4.
13C NMR (100 MHz, CDCl3): d = 139.9, 136.7, 128.7, 128.2, 126.1,
109.1, 97.3, 79.4, 34.0, 31.1, 25.1.
MS (EI, 70 eV): m/z = 248 [M+].
MS (EI, 70 eV): m/z = 196 [M+].
HRMS (EI): m/z calcd for C16H12O1N2: 248.0944; found: 248.0945.
b-(3-Thienylethynyl)styrene (4d)
MP: 89–91 °C.
1-Nitro-4-(phenylethynyl)benzene (2o)
Yield: 67 mg (30%); yellow solid; mp 116–118 °C (Lit.10 120–
121 °C).
1H NMR (400 MHz, acetone-d6): d = 7.64–7.67 (m, 1 H, ArH),
7.50–7.55 (m, 3 H, ArH), 7.27–7.39 (m, 3 H, ArH), 7.17 (dd,
J = 1.10 Hz, 1 H, ArH), 7.04 (d, J = 16.29 Hz, 1 H, alkenyl H), 6.53
(d, J = 16.29 Hz, 1 H, alkenyl H).
13C NMR (100 MHz, acetone-d6): d = 141.1, 136.4, 129.6, 128.8,
128.7, 126.4, 126.2, 122.5, 108.0, 88.3, 86.8.
2-(Phenylethynyl)thiophene (3a)
Yield: 140 mg (76%); yellow oil.23
3-(Phenylethynyl)pyridine (3b)
MS (EI, 70 eV): m/z = 210 [M+].
Yield: 130 mg (73%); orange crystalline solid; mp 51–53 °C (Lit.23
50–51 °C).
b-[(Trimethylsilyl)ethynyl]styrene (4e)
Yield: 130 mg (65%); yellow oil.32
5-(Phenylethynyl)indole (3c)
Yield: 165 mg (76%); yellow solid; mp 124–128 °C (Lit.24 135 °C).
Cyclisation of 2-(Arylethynyl)aniline Derivatives; General Pro-
cedure
3-(2-Thienylethynyl)thiophene (3d)
Yield: 110 mg (63%); colourless crystalline solid; mp 97–100 °C.30
A dry Schlenk tube containing the 2-(arylethynyl)aniline derivative
(1 mmol), anhyd DMF (1 mL), and catalyst 1 (7.8 mg, 5 mol%) was
heated at 100 °C for 60 min, and then the solvent was removed in
vacuo. After cooling to r.t., the reaction mixture was chromato-
graphed (silica gel, EtOAc–hexane) to yield the corresponding in-
dole derivative 5.
2-[(2-Aminophenyl)ethynyl]thiophene (3e)
Yield: 143 mg (72%); yellow solid; mp 63–64 °C.28
3-[(2-Amino-5-chlorophenyl)ethynyl]thiophene (3f)
Yield: 177 mg (76%); light brown solid; mp 107–110 °C.
2-Phenylindole (5a)
1H NMR (400 MHz, acetone-d6): d = 7.68–7.72 (m, 1 H, ArH),
7.48–7.51 (m, 1 H, ArH), 7.19–7.24 (m, 2 H, ArH), 6.80 (d, J = 2.01
Hz, 1 H, ArH), 6.57 (dd, J = 2.01, 8.24 Hz, 1 H, ArH), 5.37 (s, 2 H,
NH2).
13C NMR (100 MHz, acetone-d6): d = 150.6, 134.8, 133.1, 129.8,
128.8, 126.0, 122.3, 116.3, 113.4, 105.6, 90.1, 84.6.
Yield: 185 mg (96%); off-white solid; mp 191–193 °C (Lit.17 188–
190 °C).
1H NMR (400 MHz, CDCl3): d = 8.30 (br s, 1 H, indolyl NH), 7.61–
7.70 (m, 3 H, ArH), 7.39–7.48 (m, 3 H, ArH), 7.30–7.35 (m, 1 H,
ArH), 7.17–7.23 (m, 1 H, ArH), 7.10–7.15 (m, 1 H, ArH), 6.82–6.85
(m, 1 H, ArH).
13C NMR (100 MHz, CDCl3): d = 138.0, 136.9, 132.5, 129.4, 129.1,
127.8, 125.3, 122.5, 120.8, 120.5, 111.0, 100.1.
MS (EI, 70 eV): m/z = 233 [M+].
5-[(2-Aminophenyl)ethynyl)]indole (3g)
Yield: 185 mg (80%); pale yellow crystalline solid; mp 183–
184 °C.
MS (EI, 70 eV): m/z = 193 [M+].
HRMS (EI): m/z calcd for C14H11N1: 193.0886; found: 193.0888.
1H NMR (400 MHz, acetone-d6): d = 10.39 (br s, 1 H, indolyl NH),
7.75–7.78 (m, 1 H, ArH), 7.38–7.42 (m, 1 H, ArH), 7.35 (t, J = 2.8
Hz, 1 H, ArH), 7.21–7.28 (m, 2 H, ArH), 7.00–7.05 (m, 1 H, ArH),
6.74 (dd, J = 0.73, 8.2 Hz, 1 H, ArH), 6.56 (td, J = 1.1, 7.4 Hz, 1 H,
ArH), 6.45–6.47 (m, 1 H, ArH), 5.04 (s, 2 H, NH2).
13C NMR (100 MHz, acetone-d6): d = 149.2, 136.0, 131.6, 129.1,
128.2, 126.1, 124.8, 123.9, 116.5, 114.0, 113.9, 111.5, 107.8, 101.8,
96.1, 83.5.
2-(5-Indolyl)indole (5b)
Yield: 211 mg (91%); light brown solid; mp 146 °C (dec.)
1H NMR (400 MHz, acetone-d6): d = 10.50 (br s, 1 H, indolyl NH),
10.28 (br s, 1 H, indolyl NH), 7.97–7.98 (m, 1 H, ArH), 7.56 (dd,
J = 1.7 Hz, 1.8 Hz, 1 H, ArH), 7.39–7.46 (m, 2 H, ArH), 7.30 (dd,
J = 0.9, 0.9 Hz, 2 H, ArH), 7.26–7.29 (m, 1 H, ArH), 6.88–6.98 (m,
2 H, ArH), 6.69 (dd, J = 0.7, 0.7 Hz, 1 H, ArH), 6.41–6.45 (m, 1 H,
ArH).
13C NMR (100 MHz, acetone-d6): d = 140.1, 137.4, 136.1, 129.8,
128.6, 125.8, 124.2, 120.9, 119.8, 119.7, 119.4, 116.9, 111.8, 110.9,
102.0, 97.5.
MS (EI, 70 eV): m/z = 232 [M+].
HRMS (EI): m/z calcd for C16H12N2: 232.0995, found: 232.0995.
b-(Phenylethynyl)styrene (4a)
MS (EI, 70 eV): m/z = 232 [M+].
Yield: 173 mg (85%); colourless crystalline solid; mp 102–103 °C
(Lit.31 96 °C).
HRMS (EI): m/z calcd for C16H12N2: 232.0995; found: 232.0996.
b-[(2-Aminophenyl)ethynyl]styrene (4b)
Yield: 165 mg (87%); dull yellow crystalline solid; mp 111–
112 °C.11
5-Chloro-2-(3-thienyl)indole (5c)
Yield: 208 mg (89%); off-white solid; mp 155–162 °C.
1H NMR (400 MHz, acetone-d6): d = 10.73 (s, 1 H, indolyl H),
7.70–7.73 (m, 1 H, ArH), 7.47–7.54 (m, 2 H, ArH), 7.42–7.46 (m,
1 H, ArH), 7.31 (s, 1 H, ArH), 6.94 (dd, J = 1.83, 1 H, ArH), 6.69–
6.72 (m, 1 H, ArH).
b-(Cyclopentylethynyl)styrene (4c)
Yield: 100 mg (51%); orange oil.
Synthesis 2009, No. 5, 829–835 © Thieme Stuttgart · New York