Chem. Pap.
4-((E)-(4-((E)-2-(thiophen-2-
yl)vinyl)phenyl)diazenyl)benzene-1,3-diol (5a)
point, the oil bath was removed and zinc (1.17 g,
18.00 mmol) was added in small portions. Once the reac-
tion subsided, an additional amount of zinc (0.58 g,
9.00 mmol) was added and the reaction mixture refluxed
for 2 h. The precipitate was filtered off while hot and the
filtrate was evaporated until an aqueous solution remained.
This was basified with 2 M NaOH aqueous solution until
pH 10, followed by extraction of the suspension with
dichloromethane. The organic phase was separated, dried
(Na2SO4) and the solvent was evaporated to give an orange
solid of compound 4.
This compound was prepared according to the general
procedure using 4a and resorcinol. Yield 40%.
Mp = 182–185 °C (EtOH–H2O, 2:1, v/v). IR (KBr, cm-1
)
m = 1097, 1224, 1492, 1595, 3301, 3529. 1H NMR
(300 MHz, acetone-d6, ppm): d 6.45 (d, J = 2.5 Hz, 1H),
6.65 (dd, J = 2.5, 8.8 Hz, 1H), 7.03–7.08 (m, 4H), 7.25 (d,
J = 3.3, 1H), 7.42 (d, J = 5.1 Hz, 1H), 7.57 (d,
J = 16.1 Hz, 1H), 7.72–7.77 (m, 3H), 7.85 (d, J = 8.6 Hz,
2H). 13C NMR (75 MHz, acetone-d6, ppm): d 103.2, 114.9,
122.8, 126.1, 127.0, 127.9, 128.8, 129.6, 130.6, 131.9,
133.6, 140.6, 142.7, 150.2, 156.6, 163.5. CHN analysis
(%): calculated: C, 67.06; H, 4.38; N, 8.69; found: C,
66.86; H, 4.19; N, 8.31.
(E)-4-(2-(thiophen-2-yl)vinyl)aniline (4a)
This compound was prepared as described in the general
procedure.
Mp = 122–125 °C
[lit.
(Freund
1953) = 128–129 °C]. IR (KBr, cm-1) m = 3442 and 3353
(NH2 stretching bands).
1-((E)-(4-((E)-2-(thiophen-2-
yl)vinyl)phenyl)diazenyl)naphthalen-2-ol (5b)
4-((1E,3E)-4-phenylbuta-1,3-dien-1-yl)aniline (4b)
This compound was prepared according to the general
procedure using 4a and 2-naphthol. Yield: 79%.
Mp = 138–140 °C (MeOH–EtOH, 1:2, v/v). IR (KBr,
cm-1) m = 925, 1184, 1247, 1488, 1558, 1588, 3008, 3342,
This compound was prepared as described in the general
procedure. Mp = 125–127 °C [lit. (Lee et al.
1999) = 123–125 °C]. IR (KBr, cm-1) m = 3375 and 3330
(NH2 stretching bands).
1
3501. H NMR (300 MHz, acetone-d6, ppm): d 6.97 (d,
J = 9.3 Hz, 1H), 7.02–7.09 (m, 2H), 7.20–7.24 (m, 2H),
7.38–7.62 (m, 4H), 7.73–7.78 (m, 3H), 7.88–7.92 (m, 2H),
8.67 (d, J = 8.0 Hz, 1H), 15.78 (s, 1H). 13C NMR
(75 MHz, acetone-d6, ppm): d 115.6, 122.0, 122.4, 125.6,
126.2, 128.1, 128.6, 128.8, 129.1, 129.6, 130.6, 131.1,
131.9, 133.2, 133.6, 140.6, 141.4, 142.7, 143.2, 175.8.
CHN analysis (%): calculated: C, 74.13; H, 4.52; N, 7.86;
found: C, 74.34; H, 4.35; N, 7.69.
(E)-4-(4-methoxystyryl)aniline (4c)
This compound was prepared as described in the general
procedure. Mp = 160–163 °C [lit. Papper et al.
2014) = 162–164 °C]. IR (KBr, cm-1) m = 3380 and 3292
(NH2 stretching bands).
General procedure for synthesis of compounds 5a–e
4-((E)-(4-((1E,3E)-4-phenylbuta-1,3-dien-1-
yl)phenyl)diazenyl)benzene-1,3-diol (5c)
A freshly prepared cold (ca. 5 °C) solution of sodium nitrite
(0.37 g, 5.50 mmol) in water (3 mL) was added portionwise
to a cold (ca. 5 °C) stirred solution of compound 4
(5.00 mmol) in aqueous HCl (50% v/v, 4 mL) at such a rate
so as to maintain the temperature below ca. 10 °C. Upon
completion of the addition, the cold solution was stirred for
20–25 min. The cold solution of the diazonium salt was
slowly added to a cold stirred solution/suspensionofaphenol
(resorcinol or 2-naphthol) (5.00 mmol) in aqueous NaOH
(10% w/v, 5 mL). The resulting cold intense red-orange
suspension was stirred for 1.5 h. The precipitated crude
product was collectedby vacuum filtration, washed well with
water and a minimum of diethyl ether, and then dried at
40 °C. Finally, recrystallization from the appropriate solvent
gave the pure compound 5.
This compound was prepared according to the general
procedure using 4b and resorcinol. Yield: 24%.
)
Mp = 109–112 °C (EtOH–H2O, 1:1, v/v). IR (KBr, cm-1
m = 981, 1103, 1155, 1473, 1596, 1664, 3016, 3257, 3442.
1H NMR (300 MHz, acetone-d6, ppm): d 6.45 (d,
J = 2.5 Hz, 1H), 6.55 (dd, J = 2.5, 8.8 Hz, 1H), 6.71 (d,
J = 15.2 Hz, 1H), 6.81–7.04 (m, 3H), 7.12–7.27 (m, 4H),
7.37–7.50 (m, 4H), 7.61 (d, J = 8.4 Hz, 2H), 7.85 (d,
J = 8.4 Hz, 2H). 13C NMR (75 MHz, acetone-d6, ppm): d
103.2, 114.9, 122.7, 126.1, 126.4, 127.0, 127.5, 127.9,
128.5, 129.2, 132.6, 137.3, 138.4, 150.0, 156.6, 163.5.
CHN analysis (%): calculated: C, 77.17; H, 5.30; N, 8.18;
found: C, 77.11; H, 5.23; N, 7.92.
123