Synthesis of dibenzoheteropines of group 13-16 elements via ring-closing metathesis

Article abstract of DOI:10.1021/jo4001993

The ring-closing metathesis (RCM) of bis(2-vinylphenyl)silanes in the presence of the second-generation Hoveyda-Grubbs catalyst in toluene at 100 C afforded dibenzo[b,f]silepines in excellent yields. Other dibenzoheteropines of group 13-16 elements were also prepared via the RCM of the corresponding heteroatom-tethered dienes.

Full text of DOI:10.1021/jo4001993

Article
pubs.acs.org/joc
Synthesis of Dibenzoheteropines of Group 13−16 Elements via Ring-
Closing Metathesis
Takanori Matsuda* and Shinya Sato
Department of Applied Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
S
* Supporting Information
ABSTRACT: The ring-closing metathesis (RCM) of bis(2-
vinylphenyl)silanes in the presence of the second-generation
Hoveyda−Grubbs catalyst in toluene at 100 °C afforded
dibenzo[b,f ]silepines in excellent yields. Other dibenzoheter-
opines of group 13−16 elements were also prepared via the
RCM of the corresponding heteroatom-tethered dienes.
Table 1. Preparation of Bis(2-vinylphenyl)silanes, -germane,
and -stannane 1
INTRODUCTION
■
Ring-closing metathesis (RCM) is a straightforward and
powerful method for the synthesis of carbo- and heterocyclic
alkenes with various ring sizes and has found wide application
in organic synthesis.1 However, examples of the utilization of
RCM for the synthesis of fully unsaturated or aromatic
compounds are relatively limited.2 Heteroles (heteroatom-
substituted cyclopentadienes) are a unique class of compounds
that possess a variety of intriguing properties, and a number of
methods for their synthesis have been developed. Thus far, the
RCM approach has been employed in the construction of
furan,3 pyrrole,4 silole,5 and germole skeletons.5a Silepine
(silacycloheptatriene) derivatives have recently been reported
to exhibit strong blue fluorescence.6 Given the successful
application of RCM in the synthesis of heterole derivatives, we
envisioned that a metathesis-based approach to the synthesis of
silepines as well as the other heteropine (heteroatom-
substituted cycloheptatriene) derivatives would also be feasible.
Herein we report the RCM of bis(2-vinylphenyl)silanes, which
leads to dibenzo[b,f ]silepines. The RCM strategy was also
successfully applied to the synthesis of other dibenzo[b,f]-
heteropines of group 13−16 elements.
RESULTS AND DISCUSSION
■
Bis(2-vinylphenyl)silane 1a was easily prepared through the
reaction of dichlorodimethylsilane with 2 equiv of (2-
vinylphenyl)lithium, which was generated in situ from 2-
bromostyrene7 and n-BuLi (Table 1). Other dienes tethered by
group 14 elements were also synthesized analogously.8
yield at 80 °C for 12 h (entry 4). With this catalyst, 94% yield
of 2a was obtained from the RCM of 1a at 100 °C for 2 h
(entry 5).
Unfortunately, the RCM of silicon-tethered dienes that have
substituted vinyl groups (e.g., 1b and 1j) was unsuccessful (eq
1). Thus, our attention was next drawn to variations on the
silicon atom and phenyl rings.
The RCM of diene 1a was examined using commercially
available catalysts (Table 2). Although no RCM was observed
when the first-generation Grubbs catalyst A was used as a
catalyst in toluene at 120 °C (entry 1), diene 1a underwent the
metathesis in the presence of 5 mol % of the second-generation
Grubbs catalyst B to give dibenzo[b,f ]silepine 2a in 72% yield
(entry 2).9 The yield did not increase significantly when the
catalyst loading was increased to 15 mol % (entry 3). The
second-generation Hoveyda−Grubbs catalyst C was found to
be an excellent catalyst for the reaction, providing 2a in 81%
Diethylsilylene- and methyl(phenyl)silylene-tethered dienes
1c and 1d underwent RCM in toluene at 100 °C in the
Received: January 31, 2013
© XXXX American Chemical Society
A
dx.doi.org/10.1021/jo4001993 | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
a b
Article
a
,
Table 2. RCM of Diene 1a
Table 3. Synthesis of Silepines by RCM of 1c−f
c
entry
catalyst [Ru]
Grubbs first (A)
conditions
yield (%)
1
2
3
4
5
toluene, 120 °C, 24 h no reaction
toluene, 120 °C, 24 h 72
Grubbs second (B)
d
B
toluene, 120 °C, 5 h
80
81
94
Hoveyda−Grubbs second (C) toluene, 80 °C, 12 h
toluene, 100 °C, 2 h
C
a
PCy3
=
tricyclohexylphosphine, SIMes
=
1,3-bis(2,4,6-
b
trimethylphenyl)imidazolidin-2-ylidene. Unless otherwise noted, 1a
was reacted in the presence of 5 mol % Ru catalyst in toluene (0.1 M).
c
d
Isolated yield. 15 mol % catalyst was used.
a
RCM was performed in the presence of 5 mol % C at 100 °C in
presence of 5 mol % of catalyst C to afford dibenzosilepines 2c
and 2d in excellent yields (Table 3, entries 1 and 2). The RCM
of 5-methyl-2-vinylphenyl (1e) and 2-vinylnaphthalen-1-yl (1f)
derivatives also led to the formation of the corresponding
silepines (2e and 2f) in 90% and 80% yields, respectively
(entries 3 and 4).10
b
toluene (0.1 M) for 2−3 h. Isolated yield.
a
Table 4. Synthesis of Group 14 Heteropines by RCM
When bis(4-methoxy-2-vinylphenyl)silane 1g was subjected
to the standard reaction conditions (toluene, 0.1 M, 5 mol %
catalyst C, 100 °C), 14-membered disilacycle 3g was obtained
in 40% yield in addition to the desired product 2g (28%)
(Table 4, entry 1).11 To minimize the formation of self-
dimerization product 3g, the metathesis reaction was
performed under dilute conditions (0.002 M). Indeed, self-
dimerization was unnoticeable at this concentration, and seven-
membered silacycle 2g was solely isolated in 93% yield (entry
2). Similar results were observed in the RCM of CF3-
substituted diene 1k (entries 3 and 4). Furthermore,
germanium- and tin-tethered dienes (1h and 1i, respectively)
were converted into the corresponding dibenzoheteropines 2h
and 2i (entries 5−8). A high yield of germepine 2h was
obtained at a concentration of 0.002 M (entry 6), whereas
suppression of the self-dimer 3i failed during the RCM of tin
derivative 1i even at 0.002 M (entry 8).
Because the metathesis-based approach for the synthesis of
silepines, germepine, and stannepine was found to be quite
general, the synthesis of other heteropines of group 13, 15, and
16 elements was subsequently investigated. Dibenzo[b,f ]-
borepines with a tricoordinate boron center have attracted
much attention as candidates for new organic electronic
materials.12 To the best of our knowledge, however, no
examples of dibenzo[b,f ]borepines with a tetracoordinate
boron center have been reported. The treatment of tris(2-
b
yield (%)
entry
1 (E, R)
conditions
2
3
1
2
3
4
5
6
7
1g (Si, OMe)
0.1 M, 100 °C, 24 h
0.002 M, 120 °C, 2 h
0.1 M, 100 °C, 3 h
0.002 M, 120 °C, 4 h
0.1 M, 100 °C, 3 h
0.002 M, 120 °C, 12 h
0.1 M, 100 °C, 24 h
0.002 M, 120 °C, 24 h
28
93
44
96
64
89
0
40
1g
1k (Si, CF3)
41
19
1k
1h (Ge, H)
1h
1i (Sn, H)
39
26
c
8
1i
57
a
Unless otherwise noted, RCM was performed in the presence of 5
mol % of C in toluene. Isolated yield. 10 mol % catalyst was used.
b
c
vinylphenyl)borane, which was prepared from BBr3 and 3 equiv
of (2-vinylphenyl)lithium, using dibenzoylmethane and 8-
quinolinol in two separate reactions afforded boron-tethered
dienes 1l (44%) and 1m (65%), respectively (Scheme 1).13 The
B
dx.doi.org/10.1021/jo4001993 | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
RCM of 1l and 1m produced spirocyclic tetracoordinate
dibenzoborepines 2l and 2m, respectively, in high yields.
methylenation of commercially available bis(2-formylphenyl)
ether, afforded exclusively dibenzo[b,f]oxepine 2p in 91% yield
via the metathesis approach (Scheme 3). Bis(2-vinylphenyl)
Scheme 1. Synthesis and RCM of Boron-Tethered Dienes 1l
and 1m
a
Scheme 3. RCM of Bis(vinylphenyl) Ether 1p and Sulfone
1q
a
a
RCM was performed at 100 °C in toluene (0.1 M) in the presence of
5 mol % C.
sulfone 1q was synthesized via ortho-formylation of diphenyl
sulfone (79%) and subsequent Wittig methylenation (76%).
The RCM of 1q furnished dibenzo[b,f]thiepine 5,5-dioxide
(2q) in excellent yield.
a
CONCLUSION
RCM was performed at 100 °C in toluene (0.1 M) in the presence of
■
5 mol % C.
In summary, we have developed a method for the synthesis of
dibenzoheteropines of group 13−16 elements via the RCM of
heteroatom-tethered dienes. The second-generation Grubbs−
Hoveyda catalyst showed superior activity in forming the
desired dibenzoheteropines.
For group 15 element analogues of dibenzoheteropines, we
synthesized the nitrogen and phosphorus derivatives, which can
be used in catalysis as ligands.14 N,N-Bis(2-vinylphenyl)-
methylamine (1n) was synthesized in three steps (73%) from
bis(2-bromophenyl)amine15 (Scheme 2). 5-Methyldibenzo-
EXPERIMENTAL SECTION
■
General. All reactions were performed with standard Schlenk
techniques under an argon or nitrogen atmosphere. Proton chemical
shifts were referenced to the residual CHCl3 signal at 7.26 ppm.
Carbon chemical shifts were referenced to the central peak of CDCl3
at 77.0 ppm.
Scheme 2. Synthesis of Dibenzoheteropines of Group 15
Elements by RCM
a
General Procedures for the Preparation of Bis(2-
vinylphenyl)silanes, -germane, and -stannane 1. A two-neck
flask was charged with 2-bromostyrene (948.4 mg, 5.18 mmol) and
THF (12 mL). The flask was cooled to −78 °C, and n-BuLi in hexane
(1.6 M, 3.2 mL, 5.1 mmol) was added dropwise. After 1 h, Me2SiCl2
(319.6 mg, 2.48 mmol) was added dropwise to the mixture, and
stirring was continued for 1 h at the same temperature. The flask was
allowed to warm to room temperature, and the reaction mixture was
diluted with hexane, filtered over a pad of Celite (hexane), and
concentrated. The residue was passed through a plug of Florisil
(hexane) and concentrated. Purification by column chromatography
on silica gel (hexane) afforded dimethylbis(2-vinylphenyl)silane (1a,
a
1
Reaction conditions for 1n: 5 mol % C, toluene, 100 °C, 1 h.
509.8 mg, 1.93 mmol, 78%): white solid, mp 57−59 °C; H NMR
Reaction conditions for 1o: 10 mol % C, p-xylene, 150 °C, 12 h.
(300 MHz, CDCl3) δ 0.61 (s, 6H), 5.08 (dd, J = 10.8, 1.2 Hz, 2H),
5.55 (dd, J = 17.4, 1.2 Hz, 2H), 6.82 (dd, J = 17.1, 10.8 Hz, 2H), 7.23−
7.30 (m, 2H), 7.34−7.41 (m, 2H), 7.50−7.57 (m, 4H); 13C NMR
(125.7 MHz, CDCl3) δ −0.3, 114.9, 125.3, 127.0, 129.6, 134.9, 136.8,
138.0, 144.0; HRMS (EI) calcd for C18H20Si [M]+ 264.1329, found
264.1336. Dienes 1b−i were analogously prepared.
[b,f]azepine (2n) was obtained in 95% yield by means of the
RCM reaction of 1n.16 The reaction of 2 equiv of (2-
vinylphenyl)magnesium bromide and phenylphosphonic di-
chloride afforded phosphorus-tethered diene 1o, which under-
went RCM under rather forceful conditions to give dibenzo-
[b,f]phosphepine oxide (2o) in good yield (Scheme 2).
Recently, dibenzo[b,f ]oxepine/thiepine was prepared via the
intramolecular Mizoroki−Heck reaction of 2-bromophenyl 2-
vinylphenyl ether/sulfide, where the formation of six-
membered products via exo-cyclization was inevitable.17
Bis(2-vinylphenyl) ether 1p, which was prepared by the Wittig
Dimethylbis(2-isopropenylphenyl)silane (1b). Yield: 63%
1
(355.2 mg); colorless oil; H NMR (500 MHz, CDCl3) δ 0.56 (s,
6H), 1.81 (s, 6H), 4.57 (s, 2H), 4.94 (s, 2H), 7.09 (d, J = 8.5 Hz, 2H),
7.18−7.23 (m, 2H), 7.27−7.32 (m, 2H), 7.51 (d, J = 6.0 Hz, 2H); 13C
NMR (125.7 MHz, CDCl3) δ 1.1, 25.3, 116.0, 125.8, 127.4, 128.5,
135.9, 136.8, 147.3, 150.7; HRMS (EI) calcd for C20H24Si [M]+
292.1642, found 292.1645.
Diethylbis(2-vinylphenyl)silane (1c). Yield: 71% (514.1 mg);
white solid; mp 76−77 °C; 1H NMR (500 MHz, CDCl3) δ 0.87 (t, J =
C
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The Journal of Organic Chemistry
Article
8.0 H, 6H), 1.17 (q, J = 7.7 Hz, 4H), 5.00 (d, J = 11.0 Hz, 2H), 5.50
(d, J = 17.0 Hz, 2H), 6.75 (dd, J = 17.0, 11.0 Hz, 2H), 7.23−7.28 (m,
2H), 7.33−7.38 (m, 2H), 7.49−7.55 (m, 4H); 13C NMR (125.7 MHz,
CDCl3) δ −4.8, 7.5, 114.6, 125.2, 126.9, 129.4, 135.4, 138.0, 144.2;
HRMS (EI) calcd for C20H24Si [M]+ 292.1642, found 292.1644.
Methyl(phenyl)bis(2-vinylphenyl)silane (1d). Yield: 55%
(430.3 mg); white solid; mp 98−101 °C; 1H NMR (300 MHz,
CDCl3) δ 0.90 (s, 3H), 5.05 (dd, J = 11.0, 0.7 Hz, 2H), 5.58 (dd, J =
17.1, 0.9 Hz, 2H), 6.81 (dd, J = 17.1, 10.8 Hz, 2H), 7.15−7.23 (m,
2H), 7.25−7.51 (m, 9H), 7.58−7.65 (m, 2H); 13C NMR (125.7 MHz,
CDCl3) δ −0.5, 114.9, 125.3, 127.0, 127.9, 129.3, 129.9, 134.7, 135.5,
136.6, 136.7, 138.3, 144.3; HRMS (EI) calcd for C23H22Si [M]+
326.1485, found 326.1493.
Dimethylbis(5-methyl-2-vinylphenyl)silane (1e). Yield: 87%
(398.0 mg); white solid; mp 73−75 °C; 1H NMR (300 MHz, CDCl3)
δ 0.59 (s, 6H), 2.34 (s, 6H), 5.02 (dd, J = 10.8, 1.2 Hz, 2H), 5.51 (dd,
J = 17.3, 1.4 Hz, 2H), 6.80 (dd, J = 17.4, 10.8 Hz, 2H), 7.15−7.20 (m,
2H), 7.30−7.33 (m, 2H), 7.45 (d, J = 7.8 Hz, 2H); 13C NMR (125.7
MHz, CDCl3) δ −0.1, 21.3, 113.9, 125.2, 130.4, 135.5, 136.4, 136.8,
137.9, 141.2; HRMS (EI) calcd for C20H24Si [M]+ 292.1642, found
292.1648.
Dimethylbis(2-vinylnaphthalen-1-yl)silane (1f). Yield: 11%
(67.6 mg); white solid; mp 95−103 °C; 1H NMR (300 MHz,
CDCl3) δ 0.97 (s, 6H), 5.18 (dd, J = 17.1, 1.5 Hz, 2H), 5.55 (dd, J =
17.1, 1.5 Hz, 2H), 7.18−7.37 (m, 6H), 7.54 (d, J = 8.4 Hz, 2H), 7.72−
7.82 (m, 4H), 8.14−8.20 (m, 2H); 13C NMR (125.7 MHz, CDCl3) δ
7.1, 116.1, 125.0, 125.2, 125.5, 128.2, 128.7, 130.0, 132.9, 136.6, 136.8,
139.5, 142.8; HRMS (EI) calcd for C26H24Si [M]+ 364.1642, found
364.1646.
Bis(4-methoxy-2-vinylphenyl)dimethylsilane (1g). Yield: 68%
(691.9 mg); white solid; mp 55−63 °C; 1H NMR (300 MHz, CDCl3)
δ 0.56 (s, 6H), 3.84 (s, 6H), 5.10 (dd, J = 10.8, 1.2 Hz, 2H), 5.55 (dd,
J = 17.1, 1.2 Hz, 2H), 6.77−6.88 (m, 4H), 7.08 (d, J = 2.4 Hz, 2H),
7.43 (d, J = 8.1 Hz, 2H); 13C NMR (125.7 MHz, CDCl3) δ 0.1, 55.0,
110.9, 112.7, 114.9, 128.4, 136.5, 138.0, 145.6, 160.8; HRMS (ESI)
calcd for C20H24O2Si [M]+ 324.1540, found 324.1545.
Dimethylbis[4-(trifluoromethyl)-2-vinylphenyl]silane (1k). A
solution of 2-bromo-5-(trifluoromethyl)benzaldehyde (2.512 g, 9.93
mmol), p-TsOH·H2O (95.1 mg, 0.50 mmol), and ethylene glycol
(731.4 g, 11.8 mmol) in toluene (10 mL) was refluxed under a Dean−
Stark trap for 1 h. After cooling to room temperature, the mixture was
quenched with saturated aqueous NaHCO3 solution and extracted
with AcOEt. The combined extracts were dried over Na2SO4, filtered,
and concentrated. The residue was purified by column chromatog-
raphy on silica gel (hexane) to afford 1-bromo-2-(1,3-dioxolan-2-yl)-4-
(trifluoromethyl)benzene (1.728 g, 5.82 mmol, 59%).
According to a procedure similar to that described for 1a, bis[2-
(1,3-dioxolan-2-yl)-4-(trifluoromethyl)phenyl]dimethylsilane (930.6
mg, 1.89 mmol, 71%) was prepared from 1-bromo-2-(1,3-dioxolan-
2-yl)-4-(trifluoromethyl)benzene (1.603 g, 5.40 mmol), n-BuLi in
hexane (1.6 M, 3.7 mL, 5.9 mmol), and Me2SiCl2 (343.2 mg, 2.65
mmol).
A solution of bis[2-(1,3-dioxolan-2-yl)-4-(trifluoromethyl)phenyl]-
dimethylsilane (1.00 g, 2.03 mmol) and p-TsOH·H2O (68.3 mg, 0.36
mmol) in acetone−H2O (1:1, 20 mL) was refluxed for 3 days. The
mixture was extracted with AcOEt, and the combined extracts were
washed with saturated aqueous NaHCO3 solution and brine. The
extracts were dried over Na2SO4, filtered, and concentrated. The
residue was purified by column chromatography on silica gel (hexane/
AcOEt = 20:1) to afford bis[2-formyl-4-(trifluoromethyl)phenyl]-
dimethylsilane (512.8 mg, 1.27 mmol, 62%).
To a methylenetriphenylphosphorane solution in THF, which was
prepared from MePPh3I (1.142 g, 2.83 mmol) and t-BuOK (305.2 mg,
2.72 mmol) in THF (30 mL) at 0 °C, was added dropwise a solution
of bis[2-formyl-4-(trifluoromethyl)phenyl]dimethylsilane (500 mg,
1.24 mmol) in THF (7 mL) at 0 °C, and then the reaction mixture
was stirred for 30 min at 0 °C. The reaction was quenched by addition
of saturated aqueous NH4Cl solution, and the resulting mixture was
extracted with AcOEt. The combined extracts were dried over Na2SO4,
filtered, and concentrated. The residue was passed through a plug of
Florisil (hexane) and further concentrated. Purification by column
chromatography on silica gel (hexane) afforded 1k (278.3 mg, 0.70
1
mmol, 56%) as a white solid. Mp 59−60 °C; H NMR (500 MHz,
Dimethylbis(2-vinylphenyl)germane (1h). Yield: 88% (1.175
g); white solid; mp 39−43 °C; 1H NMR (300 MHz, CDCl3) δ 0.73 (s,
6H), 5.14 (dd, J = 10.8, 1.2 Hz, 2H), 5.60 (dd, J = 17.3, 1.0 Hz, 2H),
6.81 (dd, J = 17.1, 10.8 Hz, 2H), 7.20−7.28 (m, 2H), 7.32−7.39 (m,
2H), 7.41−7.46 (m, 2H), 7.55−7.61 (m, 2H); 13C NMR (125.7 MHz,
CDCl3) δ −0.4, 115.0, 125.2, 127.2, 129.1, 134.2, 137.9, 139.2, 143.3;
HRMS (EI) calcd for C18H2074Ge [M]+ 310.0771, found 310.0786.
Dimethylbis(2-vinylphenyl)stannane (1i). Yield: 78% (336.0
CDCl3) δ 0.06 (s, 6H), 5.20 (d, J = 11.0 Hz, 2H), 5.62 (d, J = 17.0 Hz,
2H), 6.73 (dd, J = 17.0, 11.0 Hz, 2H), 7.51 (d, J = 7.5 Hz, 2H), 7.63
(d, J = 8.5 Hz, 2H), 7.74 (s, 2H); 13C NMR (125.7 MHz, CDCl3) δ
−0.7, 117.2, 122.1 (q, 3JC−F = 3.8 Hz), 123.4 (q, 3JC−F = 3.8 Hz), 124.1
(q, 1JC−F = 272.2 Hz), 132.1 (q, 2JC−F = 32.4 Hz), 135.2, 136.5, 140.4,
144.7; HRMS (EI) calcd for C20H18F6Si [M]+ 400.1076, found
400.1079.
(Z)-[(3-Oxo-1,3-diphenylprop-1-en-1-yl)oxy]bis(2-
vinylphenyl)borane (1l). To a solution of (2-vinylphenyl)lithium,
which was prepared from 2-bromostyrene (989.4 mg, 5.41 mmol) in
THF and n-BuLi in hexane (1.6 M, 3.4 mL, 5.4 mmol) in THF (27
mL) at −78 °C over a period of 1 h, was added BBr3 (0.17 mL, 1.79
mmol), and then the mixture was allowed to warm to room
temperature. After heating for 12 h at 90 °C, the reaction mixture
was treated with a solution of dibenzoylmethane (406.5 mg, 1.81
mmol) in THF (8.2 mL), which was added dropwise. After refluxing
the resulting mixture for 6 h, it was concentrated under reduced
pressure to remove the volatile materials. The residue was purified by
column chromatography on silica gel (CHCl3). Recrystallization from
CHCl3−hexane afforded the title compound (350.7 mg, 0.80 mmol,
44%) as a yellow solid. Mp 207−216 °C; 1H NMR (500 MHz,
CDCl3) δ 5.01 (d, J = 12.5 Hz, 2H), 5.46 (d, J = 18.5 Hz, 2H), 7.0 (s,
1H), 7.14−7.26 (m, 4H), 7.31 (dd, J = 17.0, 11.0 Hz, 2H), 7.49−7.55
(m, 8H), 7.62−7.68 (m, 2H), 8.15 (d, J = 8.5 Hz, 2H); 13C NMR
(125.7 MHz, CDCl3) δ 93.8, 112.4, 125.4, 126.3, 127.1, 128.7, 128.9,
132.7, 133.1, 134.4, 139.6, 141.9, 182.4 [carbon attached to boron was
not observed due to quadrupole broadening caused by the boron
nucleus]; HRMS (EI) calcd for C31H2511BO2 [M]+ 440.1942, found
440.1946.
1
mg); colorless oil; H NMR (500 MHz, CDCl3) δ 0.57 (s, 6H), 5.20
(d, J = 11.0 Hz, 2H), 5.63 (d, J = 17.0 Hz, 2H), 6.76 (dd, J = 17.0, 10.0
Hz, 2H), 7.18−7.25 (m, 2H), 7.36−7.46 (m, 4H), 7.56−7.64 (m, 2H);
13C NMR (125.7 MHz, CDCl3) δ −7.4, 115.4, 125.1, 127.2, 129.0,
136.7, 139.4, 141.1, 144.8; HRMS (EI) calcd for C17H17Sn [M −
CH3]+ 341.0347, found 341.0346.
Dimethyl(2-isopropenylphenyl)(2-vinylphenyl)silane (1j). To
a THF solution of (2-isopropenylphenyl)lithium, which was prepared
from 1-bromo-2-isopropenylbenzene (662.2 mg, 3.36 mmol) in THF
(7.6 mL) and n-BuLi in hexane (1.6 M, 1.9 mL, 3.0 mmol) at −78 °C,
was added dropwise chlorodimethyl(2-vinylphenyl)silane (1.20 g, 6.10
mmol). After stirring for 1 h at −78 °C, the reaction mixture was
allowed to warm to room temperature and then was diluted with water
and extracted with AcOEt. The combined extracts were dried over
Na2SO4, filtered, and concentrated. The residue was purified by
column chromatography on silica gel (hexane) to afford the title
1
compound (516.0 mg, 1.85 mmol, 61%) as a colorless oil. H NMR
(300 MHz, CDCl3) δ 0.59 (s, 6H), 1.76 (dd, J = 1.5, 0.9 Hz, 3H),
4.64−4.67 (m, 1H), 4.90−4.95 (m, 1H), 5.05 (dd, J = 10.8, 1.2 Hz,
1H), 5.52 (dd, J = 17.3, 1.4 Hz, 1H), 6.77 (dd, J = 17.1, 10.8 Hz, 1H),
7.09−7.14 (m, 1H), 7.20−7.27 (m, 2H), 7.30−7.38 (m, 2H), 7.48−
7.57 (m, 3H); 13C NMR (125.7 MHz, CDCl3) δ 0.6, 25.1, 114.6,
116.1, 125.0, 126.1, 126.7, 127.5, 128.8, 129.2, 135.1, 135.5, 135.7,
138.0, 138.3, 143.7, 147.2, 151.1; HRMS (EI) calcd for C19H22Si [M]+
278.1485, found 278.1493.
(Quinolin-8-yloxy)bis(2-vinylphenyl)borane (1m). According
to a procedure similar to that described for 1l, 1m (429.9 mg, 1.19
mmol, 66%) was prepared from 2-bromostyrene (1.021 g, 5.58 mmol),
n-BuLi in hexane (1.6 M, 3.4 mL, 5.4 mmol), BBr3 (0.17 mL, 1.79
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mmol), and 8-hydroxyquinoline (266.5 mg, 1.84 mmol). Yellow solid;
mp 207−210 °C; 1H NMR (500 MHz, CDCl3) δ 4.90 (d, J = 12.0 Hz,
2H), 5.43 (dd, J = 17.0 Hz, 2H), 7.04 (dd, J = 17.7, 10.3 Hz, 2H),
7.09−7.25 (m, 8H), 7.51 (d, J = 7.0 Hz, 2H), 7.59−7.67 (m, 2H), 8.40
(d, J = 7.5 Hz, 1H), 8.65 (d, J = 5.0 Hz, 1H); 13C NMR (125.7 MHz,
CDCl3) δ 110.1, 112.2, 113.2, 122.5, 125.8, 126.9, 127.2, 128.4, 131.6,
132.8, 137.6, 138.8, 139.3, 140.9, 141.6, 158.2 [carbon attached to
boron was not observed due to quadrupole broadening caused by the
boron nucleus]; HRMS (EI) calcd for C25H2011BNO [M]+ 361.1632,
found 361.1636.
N,N-Bis(2-vinylphenyl)methylamine (1n). A solution of bis(2-
bromophenyl)amine (2.199 g, 6.72 mmol) in THF (5.0 mL) was
added dropwise to a suspension of NaH (60% in mineral oil, 509.1 mg,
12.7 mmol) in THF (5.0 mL) at 0 °C. After stirring for 30 min at 0
°C, the mixture was treated with MeI (0.79 mL, 12.7 mmol). The
reaction mixture was allowed to warm to room temperature and was
further stirred for 3 h. The reaction mixture was diluted with water and
extracted with AcOEt. The combined extracts were dried over Na2SO4,
filtered, and concentrated. The residue was purified by column
chromatography on silica gel (hexane) to afford N,N-bis(2-
bromophenyl)methylamine (1.964 g, 5.76 mmol, 86%).
To a solution of N,N-bis(2-bromophenyl)methylamine (1.921 g,
5.63 mmol) in THF (12 mL) was added n-BuLi in hexane (1.6 M, 7.7
mL, 12.3 mmol) at −78 °C. After 1 h, DMF (0.94 mL, 12.2 mmol)
was added to the mixture at −78 °C, and then the reaction mixture
was allowed to warm to room temperature. The reaction mixture was
diluted with water and extracted with AcOEt. The combined extracts
were dried over Na2SO4, filtered, and concentrated. The residue was
purified by column chromatography on silica gel (hexane/AcOEt =
5:1) to afford N,N-bis(2-formylphenyl)methylamine (1.152 g, 4.81
mmol, 85%).
Bis(2-vinylphenyl) Sulfone (1q). To a solution of diphenyl
sulfone (1.00 g, 4.58 mmol) in THF (46 mL) was added n-BuLi in
hexane (1.6 M, 6.3 mL, 10.1 mmol) dropwise at −78 °C, and the
resulting mixture was stirred for 1 h at −78 °C. To the mixture was
added DMF (750.1 mg, 10.3 mmol), and the reaction mixture was
allowed to warm to room temperature. The reaction was quenched by
addition of AcOH (2.0 mL) and water (50 mL), and the resulting
mixture was extracted with AcOEt. The combined extracts were
washed with 0.2 M HCl aqueous solution and brine. The extracts were
dried over Na2SO4, filtered, and concentrated. The residue was
purified by column chromatography on silica gel (hexane/AcOEt =
2:1) to afford bis(2-formylphenyl) sulfone (987.8 mg, 3.60 mmol,
79%).
According to a procedure similar to that described for 1k, 1q (737.9
mg, 2.73 mmol, 76%) was prepared from bis(2-formylphenyl) sulfone
(987.8 mg, 3.60 mmol), MePPh3I (3.281 g, 8.12 mmol), and t-BuOK
(890.1 mg, 7.93 mmol). White solid; mp 134−138 °C; 1H NMR (300
MHz, CDCl3) δ 5.18 (dd, J = 10.9, 1.1 Hz, 2H), 5.45 (dd, J = 17.3, 1.0
Hz, 2H), 7.18−7.30 (m, 2H), 7.40−7.58 (m, 6H), 8.13−8.18 (m, 2H);
13C NMR (125.7 MHz, CDCl3) δ 118.5, 127.5, 128.1, 129.3, 132.9,
133.5, 137.7, 138.0; HRMS (ESI) calcd for C16H14NaO2S+ [M]+
293.0607, found 293.0579.
General Procedure for the Ring-Closing Metathesis of
Heteroatom-Tethered Dienes 1. Synthesis of 5,5-Dimethyl-
5H-dibenzo[b,f ]silepine (2a). A Schlenk tube equipped with a
reflux condenser under Ar was charged with Hoveyda−Grubbs
second-generation catalyst C (3.2 mg, 5.1 μmol) and diene 1a (26.8
mg, 0.101 mmol) (liquid substrates were added via syringe after
toluene). Toluene (1.0 mL) was added via syringe through the
septum. The mixture was heated at 100 °C for 2 h. The reaction
mixture was then filtered through a plug of Florisil while washing with
hexane−AcOEt (10:1), and the filtrate was concentrated. Purification
of the residue by preparative TLC on silica gel (hexane/AcOEt =
According to a procedure similar to that described for 1k, 1n (873.6
mg, 3.71 mmol, 87%) was prepared from N,N-bis(2-formylphenyl)-
methylamine (1.015 g, 4.24 mmol), MePPh3I (3.812 g, 9.43 mmol),
1
50:1) afforded 2a (22.4 mg, 0.095 mmol, 94%) as a colorless oil. H
and 13C NMR spectra were identical to those in the literature.6
5,5-Diethyl-5H-dibenzo[b,f]silepine (2c). The general proce-
dure was followed using 1c (29.3 mg, 0.100 mmol), C (3.2 mg, 5.1
μmol), and toluene (1.0 mL); 100 °C, 3 h. Purification by preparative
TLC on silica gel (hexane/AcOEt = 50:1) yielded 2c (24.4 mg, 0.092
1
and t-BuOK (1.033 g, 9.21 mmol). White solid; mp 98−99 °C; H
NMR (500 MHz, CDCl3) δ 3.1 (s, 3H), 5.08 (d, J = 11.0 Hz, 2H),
5.55 (d, J = 18.5 Hz, 2H), 6.82−6.93 (m, 4H), 7.00−7.06 (m, 2H),
7.14−7.20 (m, 2H), 7.46 (d, J = 7.5 Hz, 2H); 13C NMR (125.7 MHz,
CDCl3) δ 42.4, 113.8, 122.3, 123.2, 127.0, 128.4, 132.4, 134.1, 149.4;
HRMS (EI) calcd for C17H17N [M]+ 235.1356, found 235.1362.
Phenylbis(2-vinylphenyl)phosphine Oxide (1o). At 0 °C,
phenylphosphonic dichloride (1.546 g, 7.93 mmol) was added to a
solution of (2-vinylphenyl)magnesium bromide in THF, which was
prepared from 2-bromostyrene (3.01 g, 16.5 mmol), Mg (399.2 mg,
16.4 mmol), and THF (10 mL) at 95 °C over a period of 6 h. After
stirring at room temperature for 12 h, the reaction was quenched with
0.1 M H2SO4 (30 mL). The mixture was extracted with CHCl3, and
the combined extracts were washed with saturated aqueous NaHCO3
solution, dried over Na2SO4, and concentrated. The residue was
purified by column chromatography on silica gel (CHCl3) to afford the
title compound (1.776 g, 5.38 mmol, 68%) as a white solid. Mp 202−
1
mmol, 92%) as a colorless oil. H NMR (500 MHz, CDCl3) δ 1.02−
1.14 (m, 10H), 6.93 (s, 2H), 7.31−7.40 (m, 6H), 7.61 (d, J = 7.0 Hz,
2H); 13C NMR (125.7 MHz, CDCl3) δ 1.5, 7.7, 127.2, 128.8, 129.8,
133.1, 133.3, 135.4, 141.9; HRMS (EI) calcd for C18H20Si [M]+
264.1329, found 264.1336.
5-Methyl-5-phenyl-5H-dibenzo[b,f ]silepine (2d). The general
procedure was followed using 1d (32.7 mg, 0.100 mmol), C (3.2 mg,
5.1 μmol), and toluene (1.0 mL); 100 °C, 3 h. Purification by
preparative TLC on silica gel (hexane/AcOEt = 10:1) yielded 2d (26.3
1
mg, 0.088 mmol, 88%) as a white solid. Mp 126−129 °C; H NMR
(500 MHz, CDCl3) δ 0.85 (s, 3H), 6.86 (s, 2H), 7.25−7.44 (m, 11H),
7.62 (d, J = 7.5 Hz, 2H); 13C NMR (125.7 MHz, CDCl3) δ −5.3,
127.3, 127.5, 129.2, 129.3, 129.8, 133.1, 133.9, 134.9, 135.1, 135.3,
141.9; HRMS (EI) calcd for C21H18Si [M]+ 298.1172, found 298.1182.
3,5,5,7-Tetramethyl-5H-dibenzo[b,f]silepine (2e). The general
procedure was followed using 1e (29.2 mg, 0.100 mmol), C (3.1 mg,
4.9 μmol), and toluene (1.0 mL); 100 °C, 2 h. Purification by
preparative TLC on silica gel (hexane) yielded 2e (23.7 mg, 0.090
1
208 °C; H NMR (500 MHz, CDCl3) δ 5.16 (d, J = 11.0 Hz, 2H),
5.62 (d, J = 17.5 Hz, 2H), 7.03−7.10 (m, 2H), 7.16−7.21 (m, 2H),
7.42−7.56 (m, 7H), 7.56−7.63 (m, 2H), 7.68−7.73 (m, 2H); 13C
NMR (125.7 MHz, CDCl3) δ 116.7, 126.7 (d, JC−P = 10.3 Hz), 126.9
(d, JC−P = 13.4 Hz), 128.4 (d, JC−P = 12.4 Hz), 129.9 (d, JC−P = 101.3
Hz), 131.8 (d, JC−P = 3.1 Hz), 132.1 (d, JC−P = 2.1 Hz), 132.27 (d, JC−P
= 10.3 Hz), 132.34, 133.2 (d, JC−P = 12.4 Hz), 135.4 (d, JC−P = 6.3
Hz), 142.7 (d, JC−P = 6.2 Hz); HRMS (ESI) calcd for C22H19OP [M]+
330.1168, found 330.1171.
1
mmol, 90%) as a white solid. Mp 88−91 °C; H NMR (300 MHz,
CDCl3) δ 0.50 (s, 6H), 2.37 (s, 6H), 6.90 (s, 2H), 7.14−7.20 (m, 2H),
7.24−7.29 (m, 2H), 7.34−7.38 (m, 2H); 13C NMR (125.7 MHz,
CDCl3) δ −4.6, 21.2, 129.5, 129.7, 132.2, 133.0, 136.8, 137.0, 138.9;
HRMS (EI) calcd for C18H20Si [M]+ 264.1329, found 264.1335.
15,15-Dimethyl-15H-dinaphtho[1,2-b:2′,1′-f ]silepine (2f).
The general procedure was followed using 1f (36.3 mg, 0.100
mmol), C (3.1 mg, 4.9 μmol), and toluene (1.0 mL); 100 °C, 3 h.
Purification by preparative TLC on silica gel (hexane/AcOEt = 20:1)
yielded 2f (26.9 mg, 0.080 mmol, 80%) as a white solid. Mp 139−144
°C; 1H NMR (300 MHz, CDCl3) δ 0.99 (s, 6H), 7.39 (s, 2H), 7.45−
7.62 (m, 6H), 7.78−7.86 (m, 4H), 8.79 (d, J = 8.7 Hz, 2H); 13C NMR
(125.7 MHz, CDCl3) δ 4.9, 125.4, 126.0, 127.5, 128.5, 128.6, 129.0,
Bis(2-vinylphenyl) Ether (1p). According to a procedure similar
to that described for 1k, 1p (98.0 mg, 0.44 mmol, 99%) was prepared
from bis(2-formylphenyl) ether (101.1 mg, 0.45 mmol), MePPh3I
(403.1 mg, 1.00 mmol), and t-BuOK (109.1 mg, 0.97 mmol).
1
Colorless oil; H NMR (500 MHz, CDCl3) δ 5.30 (d, J = 10.5 Hz,
2H), 5.82 (d, J = 18.0 Hz, 2H), 6.75 (d, J = 7.5 Hz, 2H), 7.01−7.12
(m, 4H), 7.15−7.22 (m, 2H), 7.61 (d, J = 7.5 Hz, 2H); 13C NMR
(125.7 MHz, CDCl3) δ 115.3, 118.6, 123.5, 126.6, 128.91, 128.95,
131.0, 154.3; HRMS (EI) calcd for C16H14O [M]+ 222.1039, found
222.1046.
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133.2, 133.4, 135.4, 136.7, 140.4; HRMS (ESI) calcd for C24H20Si
[M]+ 336.1329, found 336.1336.
(50 mL); 120 °C, 24 h. Purification by preparative TLC on silica gel
(hexane/AcOEt = 50:1) yielded 2i (18.4 mg, 0.056 mmol, 57%) and
3i (8.5 mg, 0.013 mmol, 26%).
2,8-Dimethoxy-5,5-dimethyl-5H-dibenzo[b,f ]silepine (2g)
and 2,8,13,19-Tetramethoxy-5,5,16,16-tetramethyl-5,16-
dihydrotetrabenzo[b,f,i,m][1,8]disilacyclotetradecine (3g). The
general procedure was followed using 1g (32.3 mg, 0.100 mmol), C
(3.1 mg, 4.9 μmol), and toluene (1.0 mL); 100 °C, 24 h. Purification
by preparative TLC on silica gel (hexane/AcOEt = 8:1) yielded 2g
(8.3 mg, 0.030 mmol, 28%) and 3g (11.8 mg, 0.020 mmol, 40%).
2g: colorless oil; 1H NMR (300 MHz, CDCl3) δ 0.46 (s, 6H), 3.81
(s, 6H), 6.87−6.93 (m, 6H), 7.44−7.50 (m, 2H); 13C NMR (125.7
MHz, CDCl3) δ −4.2, 55.1, 113.7, 114.5, 129.4, 133.3, 133.8, 142.8,
160.3; HRMS (ESI) calcd for C18H20O2Si [M]+ 296.1227, found
296.1231.
2i: colorless oil; 1H and 13C NMR spectra were identical to those in
the literature.12a,19 HRMS (EI) calcd for C15H13120Sn [M − CH3]+
313.0034, found 313.0039.
1
3i: white solid; mp 172−177 °C; H NMR (500 MHz, CDCl3) δ
0.55 (s, 12H, 2JSn−H = 52.5 Hz), 6.56 (s, 4H), 6.94 (d, J = 8.5 Hz, 4H),
7.06 (t, J = 8.0 Hz, 4H), 7.18 (t, J = 7.2 Hz, 4H), 7.50 (d, J = 7.5 Hz,
4H); 13C NMR (125.7 MHz, CDCl3) δ −8.1, 125.1, 126.6, 128.8,
133.6, 135.6, 142.7, 145.2; HRMS (EI) calcd for C32H32116Sn2 [M]+
648.0533, found 648.0546.
(Z)-5-[(3-Oxo-1,3-diphenylprop-1-en-1-yl)oxy]-5H-dibenzo-
[b,f ]borepine (2l). The general procedure was followed using 1l
(44.0 mg, 0.100 mmol), C (3.1 mg, 4.9 μmol), and toluene (1.0 mL);
120 °C, 24 h. Purification by preparative TLC on silica gel (CHCl3/
hexane = 3:1) yielded 2l (38.6 mg, 0.094 mmol, 94%) as a yellow
1
3g: white solid; mp 155−159 °C; H NMR (500 MHz, CDCl3) δ
0.57 (s, 12H), 3.68 (s, 12H), 6.48 (d, J = 2.0 Hz, 4H), 6.63 (s, 4H),
6.79 (dd, J = 8.5, 2.5 Hz, 4H), 7.51 (d, J = 8.5 Hz, 4H); 13C NMR
(125.7 MHz, CDCl3) δ 1.2, 54.8, 109.8, 113.0, 129.5, 133.0, 135.6,
146.1, 160.4; HRMS (EI) calcd for C36H40O4Si2 [M]+ 592.2460, found
592.2460.
1
solid. Mp 277−285 °C; H NMR (500 MHz, CDCl3) δ 6.95 (s, 1H),
7.13 (s, 2H), 7.22−7.30 (m, 4H), 7.42−7.47 (m, 2H), 7.51−7.58 (m,
4H), 7.62−7.68 (m, 4H), 8.14 (d, J = 8.5 Hz, 4H); 13C NMR (125.7
MHz, CDCl3) δ 93.2, 126.3, 126.7, 128.6, 129.0, 129.2, 129.3, 131.9,
133.4, 134.3, 138.7, 182.7 [carbon attached to boron was not observed
due to quadrupole broadening caused by the boron nucleus]; HRMS
(EI) calcd for C29H2010BO2 [M − H]+ 410.1587, found 410.1600.
5-(Quinolin-8-yloxy)-5H-dibenzo[b,f ]borepine (2m). The gen-
eral procedure was followed using 1m (36.3 mg, 0.100 mmol), C (3.0
mg, 4.8 μmol), and toluene (1.0 mL); 100 °C, 3 h. Purification by
preparative TLC on silica gel (CHCl3) yielded 2m (31.4 mg, 0.094
mmol, 94%) as a yellow solid. Mp 274−276 °C; 1H NMR (300 MHz,
CDCl3) δ 7.10 (s, 2H), 7.14 (d, J = 8.1 Hz, 1H), 7.22−7.32 (m, 5H),
7.37 (d, J = 7.8 Hz, 1H), 7.39−7.46 (m, 2H), 7.65 (t, J = 8.1 Hz, 1H),
7.91−7.98 (m, 2H), 8.17 (d, J = 8.4 Hz, 1H), 8.96 (d, J = 5.1 Hz, 1H);
13C NMR (75.5 MHz, CDCl3) δ 109.4, 112.6, 122.8, 127.0, 127.7,
128.3, 130.0, 131.1, 132.2, 133.1, 136.0, 137.9, 138.5, 140.9, 158.6
[carbon attached to boron was not observed due to quadrupole
broadening caused by the boron nucleus]; HRMS (EI) calcd for
C23H1510BNO [M − H]+ 333.1278, found 331.1287.
A reaction that was performed using 1g (32.8 mg, 0.101 mmol), C
(3.2 mg, 5.1 μmol), and toluene (50 mL) at 120 °C for 2 h afforded 2g
(27.8 mg, 0.094 mmol, 93%), exclusively.
5,5-Dimethyl-2,8-bis(trifluoromethyl)-5H-dibenzo[b,f ]-
silepine (2k) and 5,5,16,16-Tetramethyl-2,8,13,19-tetrakis-
(trifluoromethyl)-5,16-dihydrotetrabenzo[b,f,i,m][1,8]-
disilacyclotetradecine (3k). The general procedure was followed
using 1k (40.2 mg, 0.100 mmol), C (3.2 mg, 5.1 μmol), and toluene
(1.0 mL); 100 °C, 3 h. Purification by preparative TLC on silica gel
(hexane) yielded 2k (16.4 mg, 0.044 mmol, 44%) and 3k (15.2 mg,
0.020 mmol, 41%).
2k: white solid; mp 91−94 °C; 1H NMR (500 MHz, CDCl3) δ 0.56
(s, 6H), 7.08 (s, 2H), 7.59 (d, J = 8.5 Hz, 2H), 7.63 (s, 2H), 7.69 (d, J
= 7.0 Hz, 2H); 13C NMR (75.5 MHz, CDCl3) δ −5.1, 123.92 (q, 3JC−F
1
3
= 3.5 Hz), 123.95 (q, JC−F = 271.9 Hz), 125.8 (q, JC−F = 3.7 Hz),
2
131.4 (q, JC−F = 32.3 Hz), 133.1, 133.3, 140.9, 141.3; HRMS (EI)
calcd for C18H14F6Si [M]+ 372.0763, found 372.0769.
1
3k: white solid; mp 250−255 °C; H NMR (300 MHz, CDCl3) δ
5-Methyl-5H-dibenzo[b,f ]azepine (2n). The general procedure
was followed using 1n (23.5 mg, 0.100 mmol), C (3.2 mg, 5.1 μmol),
and toluene (1.0 mL); 100 °C, 1 h. Purification by preparative TLC on
silica gel (hexane) yielded 2n (19.6 mg, 0.095 mmol, 95%) as a yellow
solid. Mp 144−146 °C (lit.20 148 °C); 1H NMR (300 MHz, CDCl3) δ
3.33 (s, 3H), 6.69 (s, 2H), 6.93−7.05 (m, 6H), 7.21−7.28 (m, 2H);
13C NMR (125.7 MHz, CDCl3) δ 39.3, 118.8, 123.1, 128.9, 129.2,
132.4, 132.9, 152.3; HRMS (EI) calcd for C15H14N+ [M]+ 208.1121,
found 208.1104.
0.64 (s, 12H), 6.54 (s, 4H), 7.06 (br s, 4H), 7.45 (dd, J = 7.8, 1.2 Hz,
4H), 7.71 (d, J = 7.8 Hz, 4H); 13C NMR (75.5 MHz, CDCl3) δ −0.1,
1
2
120.5 (q), 123.3 (q), 123.6 (q, JC−F = 272.1 Hz), 131.7 (q, JC−F
=
32.5 Hz), 133.3, 134.2, 142.1, 143.6; HRMS (EI) calcd for
C36H28F12Si2 [M]+ 744.1532, found 744.1538.
The reaction carried out using 1k (40.1 mg, 0.100 mmol), C (3.2
mg, 5.1 μmol), and toluene (50 mL) at 120 °C for 4 h afforded 2k
(35.7 mg, 0.096 mmol, 96%), exclusively.
5,5-Dimethyl-5H-dibenzo[b,f ]germepine9b,18 (2h) and
5,5,16,16-Tetramethyl-5,16-dihydrotetrabenzo[b,f,i,m][1,8]-
digermacyclotetradecine (3h). The general procedure was
followed using 1h (31.0 mg, 0.100 mmol), C (3.2 mg, 5.1 μmol),
and toluene (1.0 mL); 100 °C, 3 h. Purification by preparative TLC on
silica gel (hexane) yielded 2h (18.0 mg, 0.064 mmol, 64%) and 3h (5.3
mg, 0.009 mmol, 19%).
5-Phenyl-5H-dibenzo[b,f ]phosphepine 5-oxide (2o). The
general procedure was followed using 1o (33.5 mg, 0.101 mmol), C
(6.2 mg, 9.9 μmol), and toluene (1.0 mL); 150 °C, 12 h. Purification
by preparative TLC on silica gel (CHCl3/MeOH = 10:1) yielded 2o
1
(26.2 mg, 0.087 mmol, 85%) as a white solid. Mp 225−231 °C; H
NMR (500 MHz, CDCl3) δ 6.78 (s, 2H), 7.06−7.13 (m, 2H), 7.17−
7.24 (m, 2H), 7.33−7.39 (m, 1H), 7.39−7.45 (m, 2H), 7.57−7.68 (m,
4H), 8.44−8.52 (m, 2H); 13C NMR (125.7 MHz, CDCl3) δ 127.9 (d,
JC−P = 12.4 Hz), 128.6 (d, JC−P = 10.6 Hz), 129.6 (d, JC−P = 99.4 Hz),
2h: colorless oil; 1H NMR (500 MHz, CDCl3) δ 0.69 (s, 12H), 6.57
(s, 4H), 6.90 (d, J = 8.5 Hz, 4H), 7.01−7.06 (m, 4H), 7.15−7.20 (m,
4H), 7.51 (d, J = 7.5 Hz, 4H); 13C NMR (125.7 MHz, CDCl3) δ 0.0,
125.0, 126.5, 128.7, 132.7, 133.1, 140.9, 143.7; HRMS (EI) calcd for
C16H1674Ge [M]+ 282.0458, found 282.0464.
129.7 (d, JC−P = 11.2 Hz), 130.8 (d, JC−P = 11.2 Hz), 131.5 (d, JC−P
=
2.5 Hz), 131.7 (d, JC−P = 2.5 Hz), 132.19 (d, JC−P = 2.5 Hz), 132.24
(d, JC−P = 1.3 Hz), 132.3 (d, JC−P = 107.0 Hz), 136.9 (d, JC−P = 10.6
Hz); HRMS (EI) calcd for C20H15OP [M]+ 302.0855, found
302.0863.
1
3h: white solid; mp 167−180 °C; H NMR (500 MHz, CDCl3) δ
0.69 (s, 12H), 6.57 (s, 4H), 6.90 (d, J = 8.5 Hz, 4H), 7.04 (t, J = 6.8
Hz, 4H), 7.18 (t, J = 6.8 Hz, 4H), 7.51 (d, J = 7.5 Hz, 4H); 13C NMR
(125.7 MHz, CDCl3) δ 0.04, 125.0, 126.5, 128.7, 132.7, 133.1, 140.9,
143.7; HRMS (EI) calcd for C32H3270Ge2 [M]+ 556.0984, found
556.0988.
Dibenzo[b,f ]oxepine (2p). The general procedure was followed
using 1p (22.1 mg, 0.099 mmol), C (3.1 mg, 4.9 μmol), and toluene
(1.0 mL); 100 °C, 24 h. Purification by preparative TLC on silica gel
(hexane/AcOEt = 50:1) yielded 2p (17.5 mg, 0.090 mmol, 91%) as a
The reaction carried out using 1h (31.4 mg, 0.101 mmol), C (3.2
mg, 5.1 μmol), and toluene (50 mL) at 120 °C for 12 h afforded 2h
(25.4 mg, 0.090 mmol, 89%), exclusively.
5,5-Dimethyl-5H-dibenzo[b,f ]stannepine (2i) and 5,5,16,16-
Tetramethyl-5,16-dihydrotetrabenzo[b,f,i,m][1,8]-
distannacyclotetradecine (3i). The general procedure was followed
using 1i (35.2 mg, 0.099 mmol), C (6.3 mg, 10 μmol), and toluene
white solid. Mp 110−111 °C (lit.21 106−108 °C). H and 13C NMR
1
spectra were identical to those in the literature.21 HRMS (EI) calcd for
C14H10O [M]+ 194.0726, found 194.0733.
Dibenzo[b,f ]thiepine 5,5-dioxide (2q). The general procedure
was followed using 1q (27.1 mg, 0.100 mmol), C (3.2 mg, 5.1 μmol),
and toluene (1.0 mL); 100 °C, 1 h. Purification by preparative TLC on
F
dx.doi.org/10.1021/jo4001993 | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
silica gel (hexane/AcOEt = 3:2) yielded 2q (23.8 mg, 0.098 mmol,
98%) as a white solid. Mp 179−182 °C (lit.22 171−172 °C); 1H NMR
(300 MHz, CDCl3) δ 7.33 (s, 2H), 7.57−7.69 (m, 6H), 8.25−8.31 (m,
2H); 13C NMR (125.7 MHz, CDCl3) δ 126.1, 129.0, 130.6, 132.28,
132.29, 132.6, 133.8, 139.2; HRMS (EI) calcd for C14H10O2S [M]+
242.0396, found 242.0405.
(15) Liang, L.-C.; Chien, P.-S.; Lin, J.-M.; Huang, M.-H.; Huang, Y.-
L.; Liao, J.-H. Organometallics 2006, 25, 1399.
(16) For recent synthetic approaches toward dibenzazepines, see:
(a) Tsvelikhovsky, D.; Buchwald, S. L. J. Am. Chem. Soc. 2010, 132,
14048. (b) Elliott, E.-C.; Bowkett, E. R.; Maggs, J. L.; Bacsa, J.; Park, B.
K.; Regan, S. L.; O’Neill, P. M.; Stachulski, A. V. Org. Lett. 2011, 13,
́
5592. (c) Della Ca’, N.; Maestri, G.; Malacria, M.; Derat, E.; Catellani,
M. Angew. Chem., Int. Ed. 2011, 50, 12257 and references therein.
(17) Jepsen, T.; Larsen, M.; Jørgensen, M.; Nielsen, M. Synlett 2012,
23, 418.
(18) Shirani, H.; Janosik, T. Organometallics 2008, 27, 3960.
(19) Yoshida, K.; Furuyama, T.; Wang, C.; Muranaka, A.; Hashizume,
D.; Yasuike, S.; Uchiyama, M. J. Org. Chem. 2012, 77, 729.
(20) Ohta, T.; Miyata, N.; Hirobe, M. Chem. Pharm. Bull. 1981, 29,
1221.
ASSOCIATED CONTENT
■
S
* Supporting Information
1
Copies of H and 13C NMR spectra for previously unreported
compounds. This material is available free of charge via the
Internet at http://pubs.acs.org.
AUTHOR INFORMATION
■
(21) Xia, Y.; Liu, Z.; Xiao, Q.; Qu, P.; Ge, R.; Zhang, Y.; Wang, J.
Angew. Chem., Int. Ed. 2012, 51, 5714.
(22) Bergmann, E. D.; Rabinovitz, M. J. Org. Chem. 1960, 25, 828.
Corresponding Author
*E-mail: mtd@rs.tus.ac.jp.
Notes
The authors declare no competing financial interest.
REFERENCES
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