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G. Tocco et al. / Tetrahedron 64 (2008) 6755–6759
3.2.2. 6-Hexyl-6-methyldibenzo[d,f][1,3]dioxepine (4b)
Yellow sticky oil. IR (NaCl):
3100, 1600, 1480, 1220 cmꢁ1
NMR (300 MHz, CDCl3): 6.89–7.40 (m, 8H), 2.10 (t, 2H), 1.90 (s,
3H), 1.25–1.33 (m, 8H), 0.78 (t, 3H) ppm. 13C NMR (300 MHz,
n
.
1H
O
C
O
R
d
CH3
CDCl3):
d
155.3, 133.2, 127.4, 114.9, 100.4, 38.3, 31.0, 22.8, 23.6, 18.7,
ꢃ
13.0 ppm. EIMS: m/z: 296 [Mþ ]. Anal. Calcd for C20H24O2: C 81.08, H
InCl3 or ZrCl4
4a-m
(10 - 100% mol)
OH
OH
8.11. Found: C 81.03, H 8.01.
R
C
3a-m
C
H
+
H2O
3.2.3. 6-Methyl-6-(phenoxymethyl)dibenzo[d,f][1,3]dioxepine (4d)
Yellow sticky oil. IR (NaCl):
n .
3110, 1590, 1315, 1220, 1035 cmꢁ1
O
1
1H NMR (300 MHz, CDCl3):
d
7.31–7.10 (m, 6H), 6.98–6.75 (m, 7H),
R
CH3
4.82 (s, 2H), 1.95 (s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
d
157.3,
ꢃ
154.5,129.5,126.1,115.4,100.8, 74.0,19.9 ppm. EIMS: m/z: 318 [Mþ ].
Scheme 6. Chemoselectivity of InCl3 and ZrCl4 for 2,2’- dihydroxybiphenyl over water.
Anal. Calcd for C21H18O3: C 79.24, H 5.66. Found: C 79.32, H 5.59.
In conclusion, we succeeded in the high regioselective synthesis of
new 6,6-disubstituted dibenzo[d,f][1,3]dioxepines, demonstrating
that the reaction proceeds through a 2-chloroalkene intermediate
or its related vinyl cation, whose formation represents the key of
the reaction regiochemistry. The chemoselectivity of the catalysts
for 2,20-dihydroxybiphenyl over water was also investigated.
3.2.4. 6-Methyl-6-phenyldibenzo[d,f][1,3]dioxepine (4e)
Pale yellow crystals (mp 83–85 ꢀC). IR (NaCl):
n
3080,1600, 1450,
1260 cmꢁ1 1H NMR (300 MHz, CDCl3):
. d 7.42–7.38 (m, 5H), 7.35–
6.80 (m, 8H), 2.35 (s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
d
154.4,
ꢃ
140.6,129.2,128.7,127.0,125.4,115.1, 26.1 ppm. EIMS:m/z:288 [Mþ ].
Anal. Calcd for C20H16O2: C 83.33, H 5.55. Found: C 83.36, H 5.50.
3. Experimental
3.1. General
3.2.5. 6-Methyl-6-(3-fluorophenyl)dibenzo[d,f][1,3]dioxepine (4f)
Yellow sticky oil. IR (NaCl):
NMR (300 MHz, CDCl3): 7.35–7.11 (m, 4H), 6.98–7.07 (m, 8H), 1.99
n .
3100, 1640, 1400, 1228 cmꢁ1 1H
d
1H and 13C NMR were recorded by a Varian 300 MHz using
tetramethylsilane as internal standard. Microanalysis for CHN were
performed by a Carlo Erba 1106 Elemental Analyzer. IR spectra were
recorded by a Perkin Elmer 157 spectrometer.
(s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
d
155.5, 142.7, 134.9, 133.7,
ꢃ
128.2, 125.1, 119.3, 109.3, 102.8 ppm. EIMS: m/z: 306 [Mþ ]. Anal.
Calcd for C20H15FO2: C 78.43, H 4.90. Found: C 78.39, H 4.93.
GC–MS: Low resolution mass spectrometric experiments were
carried out on a Saturn 2000 ion-trap coupled with a Varian 3800
gas chromatograph (Varian, Walnut Creek, CA) operating under EI
3.2.6. 6-Methyl-6-(2-tolyl)dibenzo[d,f][1,3]dioxepine (4g)
Yellow sticky oil. IR (NaCl):
NMR (300 MHz, CDCl3): 7.85–7.60 (m, 4H), 6.98–7.42 (m, 8H), 2.32
n .
3050, 1560, 1480, 1235 cmꢁ1 1H
d
(s, 3H), 1.98 (s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
d
156.7, 140.9,
conditions (electron energy 70 eV, emission current 20 mA, ion-trap
temperature 200 ꢀC, manifold temperature 80 ꢀC, automatic gain
control (AGC) target 21,000) with the ion-trap operating in scan
mode (scan range from m/z 40–400 at a scan rate of 1 scan sꢁ1).
ꢃ
133.0,126.0,114.4,109.5, 95.6,19.9 ppm. EIMS: m/z: 302 [Mþ ]. Anal.
Calcd for C21H18O2: C 83.44, H 5.96. Found: C 83.21, H 6.00.
Aliquot of 1
m
L of solutions 1.0ꢂ10ꢁ5 M in chloroform have been
3.2.7. 6-Methyl-6-(3-tolyl)dibenzo[d,f][1,3]dioxepine (4h)
introduced into the gas chromatograph inlet. A CIP Sil-8 CB Low-
Yellow sticky oil. IR (NaCl):
NMR (300 MHz, CDCl3): 7.80–7.45 (m, 4H), 7.32–7.03 (m, 8H), 2.28
n .
3100, 1630, 1460, 1228 cmꢁ1 1H
bleed/MS capillary column (30 m, 0.25 mm i.d., 0.25 mm film
d
thickness) was used. The oven temperature was programmed from
150 ꢀC (held for 2 min) to 310 ꢀC at 30 ꢀC minꢁ1 (held for 2 min).
The temperature was then ramped to 350 at 20 ꢀC minꢁ1. The
transfer line was maintained at 250 ꢀC and the injector port 30/1
split at 270 ꢀC.
(s, 3H), 2.18 (s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
d 155.9, 138.3,
ꢃ
132.7,127.0,119.2,101.3, 21.4 ppm. EIMS: m/z: 302 [Mþ ]. Anal. Calcd
for C21H18O2: C 83.44, H 5.96. Found: C 83.46, H 5.91.
3.2.8. 6-Methyl-6-(4-tolyl)dibenzo[d,f][1,3]dioxepine (4i)
All starting materials and catalysts were purchased from com-
mercial sources and used without further treatment.
Yellow sticky oil. IR (NaCl):
NMR (300 MHz, CDCl3):
7.78 (dd, 4H, 3J 8.10 Hz, 4J 2.61 Hz), 7.28–
6.89 (m, 8H), 2.35 (s, 3H), 2.15 (s, 3H) ppm. 13C NMR (300 MHz,
n .
3120, 1550, 1450, 1210 cmꢁ1 1H
d
3.2. Typical procedure to synthesize
dibenzo[d,f][1,3]dioxepines
CDCl3):
d
154.4, 137.6, 128.9, 126.5, 119.0, 109.3, 102.8, 21.1 ppm.
ꢃ
EIMS: m/z: 302 [Mþ ]. Anal. Calcd for C21H18O2: C 83.44, H 5.96.
Found: C 83.41, H 5.93.
A mixture of 2,20-dihydroxybiphenyl (1) (5.37 mmol) and the
appropriate terminal alkyne (3a–m) (21.48 mmol) was stirred un-
der nitrogen for the period indicated (TLC) at 60 ꢀC, in the presence
of indium(III) chloride or zirconium(IV) chloride (0.54 mmol). After
reaction, the crude mixture was separated by flash-column chro-
matography (hexane/CH2Cl2 4/1 or 1/1) on alumina, obtaining the
desired product. Solid compounds were recrystallized from hex-
ane/CH2Cl2 6/1.
3.2.9. 6-Methyl-6-(2-methoxyphenyl)dibenzo[d,f][1,3]-
dioxepine (4j)
Pale yellow crystals (mp 77–80 ꢀC). IR (NaCl):
n
3110, 1660, 1480,
1310, 1220, 1050 cmꢁ1. 1H NMR (300 MHz, CDCl3):
7.50–7.03 (m,
4H), 7.28–6.82 (m, 8H), 3.68 (s, 3H), 2.20 (s, 3H) ppm. 13C NMR
d
(300 MHz, CDCl3):
d
157.6, 150.9, 130.7, 126.4, 113.0, 110.8, 99.0,
ꢃ
54.5 ppm. EIMS: m/z: 318 [Mþ ]. Anal. Calcd for C21H18O3: C 79.24, H
5.66. Found: C 79.19, H 5.68.
3.2.1. 6-Butyl-6-methyldibenzo[d,f][1,3]dioxepine (4a)
Pale yellow sticky oil. IR (NaCl):
(300 MHz, CDCl3):
7.35–6.80 (m, 8H), 2.12 (t, 2H, 3J 7.5 Hz), 1.85 (s,
3H), 1.63–1.26 (m, 4H), 1.02 (t, 3H, 3J 7 Hz) ppm. 13C NMR (300 MHz,
n
3080,1490, 1210 cmꢁ1. 1H NMR
d
3.2.10. 6-Methyl-6-(3-ethynylphenyl)dibenzo[d,f][1,3]-
dioxepine (4l)
CDCl3):
d
154.9, 127.3, 125.0, 120.1, 115.1, 99.9, 40.1, 24.0, 15.4,
Brown oil. IR (NaCl):
(300 MHz, CDCl3): 7.45–7.37 (m, 6H), 7.22–6.87 (m, 6H), 3.12 (s,
1H), 2.04 (s, 3H) ppm. 13C NMR (300 MHz, CDCl3):
165.6, 134.2,
n .
3270, 3050, 1650 cmꢁ1 1H NMR
ꢃ
10.9 ppm. EIMS: m/z: 268 [Mþ ]. Anal. Calcd for C18H20O2: C 80.60, H
d
7.46. Found: C 80.55, H 7.43.
d