D
D. Saporito, S. A. Rodriguez, and M. T. Baumgartner
Conclusion
125.1, 118.3, 112.2, 108.1. m/z (%) 113 (33), 125 (23), 126 (60),
207 (30), 239 (22), 250 (24), 252 (92), 253 (100), 254 (87). m/z
(HRMS ESI) 277.0589; calc. for C14H10N2O3þ [M þ Naþ]:
277.0584.
In summary, an economic, metal-free, and sustainable protocol
for the synthesis of biaryl compounds is reported. Structures
with different functional groups and biologically relevant het-
erocyclic moieties were obtained by photoinduction in aqueous
solution from hydroxyaryls in moderate to good yields. The use
of visible LED light irradiation, without affecting reaction
efficiency, was found as an interesting alternative for C–C bond
formation. Also, p-expanded coumarins could be obtained in a
one-pot reaction with excellent yields. All the formed products
present multiple potential applications, illustrating the versa-
tility of our protocol and paving the way for future studies of
molecular design.
4-Hydroxy-3-(2-hydroxynaphthalen-1-yl)-2H-chromen-
2-one (9)
dH (CD3COCD3, 400 MHz) 7.89 (1H, dd, J 7.9, 1.5), 7.84
(1H, s), 7.81 (1H, m), 7.64 (1H, ddd, J 8.4, 7.4, 1.6), 7.58 (1H, d,
J 8.5), 7.38 (1H, dd, J 8.0, 1.1), 7.32 (3H, m), 7.24 (1H, d, J 8.9).
dC (CD3COCD3, 100.62 MHz) 165.8, 163.0, 155.3, 154.6,
135.2, 133.1, 131.4, 129.8, 129.0, 127.4, 124.7, 124.6, 123.8,
119.5, 117.3, 117.2, 117.1, 110.6, 100.52. m/z (%) 56 (23), 63
(13), 71 (11), 87 (10), 97 (19), 113 (46), 114 (21), 192 (18), 193
(13), 194 (18), 195 (13), 300 (50), 302 (100), 303 (8), 304 (49).
m/z (HRMS electron impact ionization mode) 304.0742; calc.
for C19H12O4: 304.0736.
Experimental
General Procedure
The following procedure is representative of all the photoin-
duced reactions.
5H-Dibenzo[c,f]chromen-5-one (11)[32]
The reactions were carried out in a 50-mL three-neck round-
bottomed flask equipped with a nitrogen inlet and magnetic
stirrer. To 5 mL of degassed water (using a water vacuum pump),
potassium t-butoxide (44.6 mg, 0.398 mmol) or KOH (33.4 mg,
0.596 mmol) was added. After total dissolution of the base,
2-naphthol (42.9 mg, 0.298 mmol) was added and the mixture
stirred for 5 min, and then 4 (28.2mg, 0.108mmol) was added.
The reaction mixture was irradiated for 360 min. Irradiation was
conducted in a reactor equipped with two Philips HPI-T 400-W
lamps (l $ 350 nm, cooled with water) or with an LED lamp
(LED Lustrous Colour Xnes lamp, l ¼ 400 ꢂ 20 nm, 9.4V,
1050mA) (see Reactors section in the Supplementary Material).
After that, the reaction was stopped by adding an excess of
ammonium nitrate and 10 mL of water. The crude was then
extracted with ethyl acetate; the organic layer was dried over
Na2SO4, filtered, and vacuum-concentrated. Products were iso-
lated using column chromatography (pentane/acetone 80/20).
The halide ion concentration in the aqueous solution was deter-
mined by potentiometric titration. Darkreactions were carried out
by covering the vessel with aluminium foil before degasification.
dH (CDCl3, 400 MHz) 8.78 (1H, d, J 8.7), 8.67 (1H, d, J 8.3),
8.51 (1H, dd, J 7.9, 1.3), 7.91 (3H, m), 7.66 (2H, m), 7.56 (1H,
m), 7.50 (1H, d, J 8.9). dC (CDCl3, 100.62 MHz) 161.5, 150.5,
135.6, 134.5, 131.8, 131.7, 130.9, 129.7, 129.5, 128.4, 128.0,
126.6, 125.6, 125.2, 122.5, 117.8, 112.8. m/z (%) 81 (8), 94 (41),
109 (10), 163 (8), 187 (10), 188 (8), 189 (48), 190 (12), 218 (38),
245 (22), 246 (100), 247 (17).
6H-Tribenzo[c,f,h]chromen-6-one (13)
dH (CDCl3, 400 MHz) 8.73 (2H, m), 8.67 (2H, dd, J 8.3, 1.3),
8.59 (1H, d, J 8.3), 8.53 (1H, dd, J 7.9, 1.2), 7.89 (1H, m), 7.71
(5H, m). dC (CDCl3, 100.62 MHz) 161.3, 146.9, 135.7, 134.4,
131.5, 130.7, 129.1, 128.2, 127.8, 127.7, 127.3, 126.7, 126.3,
126.2, 123.8, 123.3, 122.7, 110.3. m/z (%) 119 (44), 134 (12),
237 (23), 239 (54), 240 (14), 268 (15), 295 (15), 296 (100), 297
(17). m/z (HMRS ESI) 319.0719; calc. for C21H12O2þ [M þ
Hþ]: 319.0730.
Supplementary Material
Materials and methods, substrate synthesis, Figs S1–S4, and
1H NMR and 13C NMR spectra of 3, 5, 7, 9, 11, and 13 are
available on the Journal’s website.
Compound Characterization
BINOL (3)[15]
Yield: 16–43 %. dH (CD3COCD3, 400 MHz) 7.90 (4H, m),
7.26 (6H, m), 7.06 (2H, m). dC (CD3COCD3, 100.62 MHz) 154.5,
135.5, 130.6, 130.0, 128.9, 127.1, 125.4, 123.7, 119.5, 115.0.
Conflicts of Interest
The authors declare no conflicts of interest.
Acknowledgements
N-(2-(2-Hydroxynaphthalen-1-yl)phenyl)acetamide (5)
This work was supported by the Consejo Nacional de Investigaciones
Cient´ıficas y Te´cnicas (CONICET) of Argentina, SECYT UNC and FON-
CYT. D.S. acknowledges CONICET for his doctoral fellowship. The
authors appreciate the collaboration of Leandro D. Mena and Paola Dieli
Crimi in this work.
dH (CDCl3, 400 MHz) 8.42 (1H, d, J 7.9), 7.86 (2H, m), 7.54
(1H, m), 7.38 (2H, m), 7.32 (3H, m), 7.23 (1H, m), 6.80 (1H, s),
5.34 (1H, s), 1.81 (3H, s). dC (CDCl3, 100.62 MHz) 151.5, 137.4,
133.0, 132.0, 130.9, 130.2, 129.3, 128.5, 127.5, 125.5, 124.2,
124.0, 122.6, 118.0, 29.4. m/z (%) 63 (3), 77 (4), 89 (3), 115 (4),
139 (5), 163(5), 189(25), 190(8), 217(100), 235(67), 259(7), 277
(35). m/z (high-resolution mass spectroscopy, electrospray ioniza-
tion (HRMS ESI)) 278.1162; calc. for C18H15NO2þ [M þ Hþ]:
278.1176.
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