Intramolecular double or triple Suzuki coupling reaction of substituted di- or tribromobenzenes. An easy synthesis of fused tri- or tetracycles with a benzene core

Article abstract of DOI:10.1016/j.jorganchem.2005.06.021

Double or triple intramolecular Suzuki coupling reaction has been developed for the efficient synthesis of tri- or tetracyclic products with a benzene core in good yields. The reaction was realized via a one-pot procedure combining the hydroboration of the CC bond in the starting aryl halides and the intramolecular Suzuki coupling.

Full text of DOI:10.1016/j.jorganchem.2005.06.021

Journal of Organometallic Chemistry 690 (2005) 5389–5395
www.elsevier.com/locate/jorganchem
Intramolecular double or triple Suzuki coupling reaction
of substituted di- or tribromobenzenes. An easy synthesis
of fused tri- or tetracycles with a benzene core
*
Shengming Ma , Bukuo Ni, Shaohui Lin, Zhiqiang Liang
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Lu, Shanghai 200032, PR China
Received 29 January 2005; received in revised form 14 June 2005; accepted 21 June 2005
Available online 2 August 2005
Abstract
Double or triple intramolecular Suzuki coupling reaction has been developed for the efficient synthesis of tri- or tetracyclic
products with a benzene core in good yields. The reaction was realized via a one-pot procedure combining the hydroboration of
the C@C bond in the starting aryl halides and the intramolecular Suzuki coupling.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Hydroboration; Suzuki coupling; Polycycles; Aryl halides; Alkenes
1. Introduction
fused tetracycles with a benzene core, respectively.
Here, we wish to report an efficient and versatile
general method of the synthesis of hexahydrobenzo-
dipyrans and dodecahydrotriphenylene via a one-pot
double or triple intramolecular Suzuki coupling
reaction.
Hexahydrobenzodipyrans-based compounds were
designed as molecular probes for determining the ste-
ric restrictions of the agonist binding site of serotonin
5-HT2A and 5-HT2C receptors and have attracted the
attention of chemists and biologists [1]. Over the past
decade, the palladium-catalyzed Suzuki coupling reac-
tion of organoboranes with alkenyl or aryl halides has
emerged as one of the most powerful methods for the
construction of sp3–sp3 C–C bonds [2–5]. Recently, an
intermolecular double Suzuki coupling protocol has
been devised as a practical route to a variety of com-
pounds [6]. To the best of our knowledge, the intra-
molecular double or triple Suzuki coupling reaction
has not been reported so far. Recently, we reported
bicyclic carbopalladation [7] and triple cyclic Heck
reactions [8] affording fused bicyclic compounds and
2. Results and discussion
2.1. Synthesis of starting materials
1,4-Dibromobenzenes having two equal C@C bond
fragments, i.e., 3a and 3b, were prepared by the treat-
ment of 2,5-dibromo-1,4-hydroquinone (1) [9] with allyl
bromide (2a) and 2-methylallyl chloride (2b), respec-
tively (Scheme 1). Compound with different C@C
bond-containing fragments 3c was obtained from the
etherification of compound 4, which was prepared from
the monoetherification of 1 with 2-methylallyl chloride
(2b), with allyl bromide (2a) (Scheme 1).
*
Corresponding author. Tel./fax: +86 2164167510.
E-mail address: masm@mail.sioc.ac.cn (S. Ma).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.06.021

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S. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 5389–5395
Br
O
(7.7 equiv.)
Br
2a
O
Br
Na2CO3, DMF, rt, 9.5 h
3a (58%)
Br
O
(6 equiv.)
Br
OH
Br
Cl
2b
KI (5.8 equiv.), K2CO3 (4 equiv.)
acetone-DMF reflux, 10 h
O
Br
HO
3b (65%)
1
Br
O
(1.1 equiv.)
Br
O
Cl
2b
+
KI(1 equiv.), K2CO3 (1 equiv.)
acetone, reflux, 10 h
O
Br
HO
Br
3b (26%)
4 (30%)
(3 equiv.)
Br
2a
Na2CO3 (4 equiv.)
DMF, rt, 5.5 h
Br
O
O
Br
3c (71%)
Scheme 1.
R
R
R
X
O
O
I
2
Na2CO3, DMF, rt
I
6
HO
I
OH
I
2a (R = H, X = Br)
2b (R = Me, X = Cl)
2c (R = n-Bu, X = Br)
5 h
25 h
11 h
6a (73%)
6b (70%)
6c (68%)
5
Bu-n
HO
I
O
I
2c (1.1 equiv.)
Na2CO3 (3 equiv.)
DMF, rt, 4 h,
7 (24%)
2a (3 equiv.)
Na2CO3 (4 equiv.)
DMF, rt, 9.5 h
Bu-n
O
O
I
I
6d (92%)
Scheme 2.

S. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 5389–5395
5391
Table 2
Using the same method, 1,3-diiodides 6a–d were
easily synthesized by etherification with the starting pre-
cursor 5 [10] as depicted in Scheme 2.
Compound 10 was prepared by the treatment of
hexabromide 12 with allylmagnesium bromide as de-
picted in Scheme 3 as reported [8].
Cyclization of 3 and 6 via intramolecular double Suzuki coupling
reaction
Entry
1
Substrates
O
Yields (%)
68%
Products
O
O
O
O
I
I
8b
6b
Bu-n
Bu-n
Bu-n
2.2. Hydroboration – intramolecular Suzuki coupling
O
O
O
2
3
4
62%
66%
50%
n-Bu
n-Bu
Bu-n
2,4-Diallyloxy-1,5-diiodobenzene (6a) was used as the
first substrate to test the double Suzuki coupling reac-
tion under different reaction conditions with the results
summarized in Table 1.
I
I
8c
6c
6d
O
O
O
I
O
I
8d
As shown in Table 1, the desired tricyclic compound
8a was obtained in 33% yield by hydroboration of 6a
with 2.2 equiv. of 9-BBN for 10 h, followed by treatment
with 5 mol% PdCl2(dppf) and 3 equiv. of aqueous so-
dium hydroxide under reflux for 19 h (Table 1, entry
1). However, tricyclic compound 8a was formed in
55% yield by using 2.4 equiv. of 9-BBN (Table 1, entry
2). Using 10 mol% of Pd(PPh3)4 as the catalyst and
aqueous NaOH or K3PO4 Æ 3H2O as the base, com-
pound 6a cyclized to afford tricyclic product 8a in 42%
and 19% yield, respectively (Table 1, entries 3 and 4).
The best results were obtained by hydroboration of 6a
with 2.4 equiv. of 9-BBN for 9 h, followed by treatment
with 10 mol% PdCl2(dppf) and 3 equiv. of aqueous
NaOH under reflux for 23 h affording 8a in 60% yield
(Table 1, entry 5).
Br
O
O
O
Br
O
9a
3a
Br
O
O
O
5
6
51%
45%
O
Br
O
9b
3b
3c
Br
O
O
Br
O
9c
reaction. Some typical examples are summarized in
Table 2.
From Table 2, it is obvious that a series of tricyclic
compounds 8b–d can be efficiently prepared from their
corresponding precursors, i.e., diiodides 6b–d in 68%,
62%, and 66% yield, respectively (Table 2, entries 1–3).
Compounds 9a–c were prepared in moderate yields from
dibromides 3a–c under the standard conditions (Table 2,
entries 4–6).
Furthermore, when 1,3,5-tribromo-2,4,6-tri(3-bute-
nyl)benzene (10) [8] was hydroborated with 3.5 equiv.
of 9-BBN at r.t. for 10 h, followed by the treatment with
10 mol% PdCl2(dppf) and 3 equiv. of aqueous NaOH
under for 24 h tetracyclic product 11 was afforded in
35% yield (Scheme 4).
Having established the standard reaction conditions
for double Suzuki coupling reaction of 6a, we tried to
investigate the scope and cyclization patterns of this
Br
Br
Br
Br
Br
MgBr
Br
Br
Br
Et2O, rt, 40min
Br
10 (78%)
12
Scheme 3.
In conclusion, a new and convenient synthesis of tri-
cycles or tetracycles with a benzene core was developed
via double or triple intramolecular Suzuki coupling
reactions. Further studies in this area are being con-
ducted in our laboratory.
Table 1
Cyclization of 6a under different reaction conditions
O
O
O
O
Pd
9-BBN
base, reflux
19-23 h
THF, rt
9-10 h
I
I
6a
8a
3. Experimental
Entry 9-BBN
(equiv.)
Pd (mol%)
Base
Yield (%)
3.1. Synthesis of starting materials
1
2
3
4
5
2.2
2.4
2.4
2.4
2.4
PdCl2(dppf) (5)
PdCl2(dppf) (5)
Pd(PPh3)4 (10)
Pd(PPh3)4 (10)
NaOH
NaOH
NaOH
33
55
42
3.1.1. 1,3,5-Tribromo-2,4,6-tri(but-30-enyl)benzene (10)
Compound 10 was prepared according to the litera-
ture [8].
K3PO4 Æ 3H2O 19
PdCl2(dppf) (10) NaOH
60

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S. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 5389–5395
Br
PdCl2(dppf) (10 mol%)
NaOH (3 equiv)
9-BBN (3.5 equiv)
THF
Br
Br
11
35%
10
Scheme 4.
3.1.2. Synthesis of 1,4-dibromo-2,5-di(allyloxy)benzene
(3a) (typical procedure A)
ture was diluted with water (10 mL), acidified with con-
centrated HCl, extracted with ethyl acetate (20 mL · 3),
and dried over MgSO4. Evaporation and flash column
chromatography on silica gel (petroleum ether/ethyl
acetate = 10:1) afforded 3b (180 mg, 26%) and 4 (180
mg, 30%) as a white solid; m.p.: 96–97 ꢁC (dichloro-
methane–petroleum ether). 1H NMR (300 MHz,
CDCl3) d 7.25 (s, 1H), 6.98 (s, 1H), 5.20 (s, 1H), 5.14
(s, 1H), 5.02 (s, 1H), 4.41 (s, 2H), 1.84 (s, 3H); IR
To a solution of 1 (2.0 g, 7.5 mmol), allyl bromide
(2a) (7.0 g, 58 mmol), and Na2CO3 (6.0 g, 57 mmol) in
DMF (30 mL) was stirred at r.t. for 9.5 h, the reaction
mixture was quenched with water (15 mL), extracted
with Et2O (20 mL · 3), washed with brine, and dried
over MgSO4. Evaporation and flash column chromatog-
raphy on silica gel (petroleum ether/ethyl ace-
tate = 20:1) gave 3a (1.52 g, 58%) as a white solid;
m.p.: 91 ꢁC (dichloromethane–petroleum ether). 1H
NMR (300 MHz, CDCl3) d 7.10 (s, 2H), 6.12–5.90 (m,
2H), 5.45 (dd, J = 17.25 and 1.27 Hz, 2H), 5.32 (dd,
J = 10.64 and 1.18 Hz, 2H), 4.53 (dd, J = 3.66 and
1.32 Hz, 4H); 13C NMR (75 MHz, CDCl3) d 149.7,
132.3, 118.8, 118.0, 111.2, 70.7; IR (KBr) m = 1648,
1492, 1359, 1211, 1066 cmꢀ1; MS (EI) m/z (%): 350
(M+, 2 · 81Br, 10.5), 348 (M+, 1 · 81Br, 1 · 79Br, 20.9),
346 (M+, 2 · 79Br, 10.7), 41 (100.0). Anal. Calc. for
C12H12Br2O2: C, 41.41; H, 3.48. Found: C, 41.44; H,
3.42.
(KBr) m = 3275, 1659, 1501, 1419, 1211, 1064 cmꢀ1
;
MS (EI) m/z (%): 324 (M+, 2 · 81Br, 6.5), 322 (M+,
1 · 81Br, 1 · 79Br, 13.4), 320 (M+, 2 · 79Br, 7.1), 55
(100.0). Anal. Calc. for C10H10Br2O2: C, 37.30; H,
3.13. Found: C, 37.40; H, 3.25.
3.1.5. Synthesis of 1,4-dibromo-2-(20-methylallyloxy)-5-
(allyloxy)benzene (3c)
The reaction of 4 (0.717 g, 2.23 mmol), Na2CO3 (0.95
g, 8.92 mmol), and allylic bromide (2a) (0.81 g, 6.68
mmol) in DMF (15 mL) afforded 3c (572 mg, 71%) as
1
a white solid; m.p.: 53–54 ꢁC (ethyl ether); H NMR
The following compounds were prepared according
to procedure A.
(300 MHz, CDCl3) d 7.11 (s, 1H), 7.09 (s, 1H), 6.10-
5.96 (m, 1H), 5.50 (dd, J = 17.10 and 1.50 Hz, 1H),
5.32 (dd, J = 10.50 and 1.50 Hz, 1H), 5.14 (s, 1H),
5.01 (s, 1H), 4.54 (d, J = 7.50 Hz, 2H), 4.43 (s, 2H),
1.84 (s, 3H); 13C NMR (75 MHz, CDCl3) d 149.8,
149.6, 140.0, 132.4, 118.9, 118.5, 118.0, 113.2, 111.1,
111.0, 73.4, 70.7, 19.3; IR (KBr) m = 1653, 1494, 1213,
1063, 1012 cmꢀ1; MS (EI) m/z (%): 364 (M+, 2 · 81Br,
5.2), 362 (M+, 1 · 81Br, 1 · 79Br, 10.8), 360 (M+,
2 · 79Br, 5.9), 55 (100.0). Anal. Calc. for C13H14Br2O2:
C, 43.13; H, 3.90. Found: C, 43.23; H, 3.97.
3.1.3. Synthesis of 1,4-dibromo-2,5-di(20-methylallyloxy)-
benzene (3b)
The reaction of 1 (0.5 g, 1.87 mmol), K2CO3 (1.05 g,
7.61 mmol), KI (1.80 g, 10.9 mmol), and 2b (1.01 g, 11.2
mmol) in acetone–DMF (20 mL/5mL) under reflux for
10 h afforded 3b (458 mg, 65%) as a white solid; m.p.:
93–94 ꢁC (ethyl acetate–petroleum ether). 1H NMR
(300 MHz, CDCl3) d 7.10 (s, 2H), 5.15 (s, 2H), 5.02 (s,
2H), 4.44 (s, 4H), 1.85 (s, 6H); 13C NMR (75 MHz,
CDCl3) d 149.6, 139.9, 118.4, 113.1, 110.9, 73.3, 19.3;
IR (KBr) m = 1654, 1496, 1215, 1075, 1048 cmꢀ1; MS
(EI) m/z (%): 378 (M+, 2 · 81Br, 6.2), 376 (M+,
1 · 81Br, 1 · 79Br, 12.5), 374 (M+, 2 · 79Br, 6.4), 55
(100.0). Anal. Calc. for C14H16Br2O2: C, 44.71; H,
4.29. Found: C, 44.71; H, 4.55.
3.1.6. Synthesis of 1,3-diiodo-4,6-di(allyloxy)benzene
(6a)
The reaction of 5 (1.0 g, 2.76 mmol), Na2CO3 (2.34 g,
22.08 mmol), and allylic bromide (2a) (2.67 g, 22.08
mmol) in DMF (15 mL) afforded 6a (855 mg, 73%) as
a white solid; m.p.: 72–73 ꢁC (ethyl ether–petroleum
ether). 1H NMR (300 MHz, CDCl3) d 8.05 (s, 1H),
6.36 (s, 1H), 6.11–5.96 (m, 2H), 5.50 (dq, J = 17.25
and 1.60 Hz, 2H), 5.33 (dq, J = 10.50 and 1.60 Hz,
2H), 4.57 (dt, J = 4.88 and 1.60 Hz, 4H); 13C NMR
(75 MHz, CDCl3) d 158.4, 146.8, 132.1, 118.0, 98.8,
3.1.4. Synthesis of 2,5-dibromo-4-(20-methylallyloxy)-
phenol (4)
The reaction of 1 (0.5 g, 1.87 mmol), K2CO3 (0.26 g,
1.87 mmol), KI (0.31 g, 1.87mmol) and, 2b (0.19 g, 2.10
mmol) in acetone (15 mL) under reflux was complete
after 10 h as monitored by TLC analysis. Then the mix-
76.5, 70.0; IR (KBr) m = 1650, 1351, 1270, 1035 cmꢀ1
MS (EI) m/z (%): 442 (M+, 47.9), 41 (100.0). Anal. Calc.
;

S. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 5389–5395
5393
for C12H12I2O2: C, 32.61; H, 2.74. Found: C, 32.71; H,
2.88.
5.19 (s, 1H), 5.03 (S, 1H), 4.60–4.53 (m, 2H), 4.49 (s,
2H), 2.15 (t, J = 7.65 Hz, 2H), 1.55–1.29 (m, 4H), 0.92
(t, J = 7.05 Hz, 3H); 13C NMR(75 MHz, CDCl3) d
158.5, 158.4, 146.8, 144.0, 132.1, 117.9, 112.4, 98.7,
76.4, 76.2, 72.0, 70.0, 32.7, 29.7, 22.5, 13.9; IR (KBr)
m = 2929, 1650, 1274, 1038 cmꢀ1; MS (EI) m/z (%):
498 (M+, 29.2), 55 (100.0). Anal. Calc. for C16H20I2O2:
C, 38.58; H, 4.05. Found: C, 38.77; H, 4.13.
3.1.7. Synthesis of 1,3-diiodo-4,6-di(20-methylallyloxy)-
benzene (6b)
The reaction of 5 (3.0 g, 8.29 mmol), Na2CO3 (7.03 g,
66.30 mmol), and 2b (6.00 g, 66.30 mmol) in DMF (15
mL) afforded 6b (2.173 g, 70%) as a white solid; m.p.:
101–102 ꢁC (ethyl ether-petroleum ether). 1H NMR
(300 MHz, CDCl3) d 8.04 (s, 1H), 6.35 (s, 1H), 5.17 (s,
2H), 5.03 (s, 2H), 4.46 (s, 4H), 1.85 (s, 6H); 13C
NMR(75 MHz, CDCl3) d 158.4, 146.7, 139.9, 113.3,
98.4, 76.2, 72.9, 19.4; IR (KBr) m = 1655, 1201, 1056
cmꢀ1; MS (EI) m/z (%): 470 (M+, 26.2), 55 (100.0).
Anal. Calc. for C14H16I2O2: C, 35.77; H, 3.43. Found:
C, 35.92; H, 3.56.
3.2. Intramolecular double or triple Suzuki coupling
reaction
3.2.1. Synthesis of 2,3,4,6,7,8-hexahydrobenzo[1,2b:5,
4b0]dipyran (8a) (typical procedure B)
To a solution of 6a (147 mg, 0.333 mmol) in anhy-
drous THF (2 mL) was added a solution of 9-BBN
(2.5 mL, 0.32 M solution in THF, 0.799 mmol) at room
temperature under N2. The reaction mixture was stirred
at this temperature for 12 h. To the borane solution thus
obtained were added PdCl2(dppf) (24 mg, 10 mol%) and
aqueous NaOH (0.34 mL of 3 M solution, 1.02 mmol) at
room temperature. The mixture was stirred under reflux
for 24 h and then cooled to r.t., H2O2 (0.5 mL, 30%) was
added. The mixture was extracted with ether, the organic
layer was washed with brine and dried over MgSO4.
Concentration and purification by flash column chroma-
tography on silica gel (petroleum ether/ethyl ace-
tate = 30:1) gave 8a (38 mg, 60%) as a white solid,
m.p.: 81 ꢁC (petroleum ether); 1H NMR (300 MHz,
CDCl3) d 6.69 (s, 1H), 6.26 (s, 1H), 4.12 (t, J = 5.05
Hz, 4H), 2.68 (t, J = 6.50 Hz, 4H), 2.01–1.90 (m, 4H);
13C NMR (75 MHz, CDCl3) d 153.6, 130.2, 114.4,
103.8, 66.4, 24.2, 22.6; IR (KBr) m = 2965, 1627, 1490,
1156, 1056 cmꢀ1; MS (EI) m/z (%): 191 (M+ + 1,
13.3), 190 (M+, 100.0). Anal. Calc. for C12H14O2: C,
75.76; H, 7.42. Found: C, 75.73; H, 7.39.
3.1.8. Synthesis of 1,3-diiodo-4,6-di(20-butylallyloxy)-
benzene (6c)
The reaction of 5 (1.0 g, 2.76 mmol), Na2CO3 (2.34 g,
22.08 mmol), and 2c (1.467 g, 8.29 mmol) in DMF (15
1
mL) afforded 6c (1.032 g, 68%) as a colorless oil; H
NMR (300 MHz, CDCl3) d 8.04 (s, 1H), 6.35 (s, 1H),
5.19 (s, 2H), 5.03 (s, 2H), 4.48 (s, 4H), 2.16 (t,
J = 7.65 Hz, 4H), 1.55–1.27 (m, 8H), 0.93 (t, J = 7.35
Hz, 6H); 13C NMR(75 MHz, CDCl3) d 158.5, 146.7,
144.0, 112.3, 98.5, 76.1, 72.0, 32.7, 29.7, 22.5, 13.9; IR
(KBr) m = 2930, 1654, 1449, 1275, 1191, 1039 cmꢀ1
;
MS (EI) m/z (%): 555 (M + 1, 10.7), 554 (M+, 15.3),
55 (100.0). Anal. Calc. for C20H28I2O2: C, 43.34; H,
5.09. Found: C, 43.64; H, 5.14.
3.1.9. Synthesis of 2,4-diiodo-5-(20-butylallyloxy)phenol
(7)
The reaction of 5 (1.0 g, 2.76 mmol), Na2CO3 (878
mg, 8.29 mmol), and 2c (538 mg, 3.04 mmol) in DMF
(10 mL) afforded 7 (308 mg, 24%) and 6c (233 mg,
The following compounds were prepared according
to procedure B.
1
15%) as a colorless oil; The data for 7: H NMR (300
MHz, CDCl3) d 7.93 (s, 1H), 6.53 (s, 1H), 5.28 (s,
1H), 5.20 (s, 1H), 5.03 (s, 1H), 4.46 (s, 2H), 2.16 (t,
J = 7.50 Hz, 2H), 1.55–1.28 (m, 4H), 0.92 (t, J = 7.20
Hz, 3H); 13C NMR (75 MHz, CDCl3) d 159.0, 156.1,
145.5, 143.7, 112.3, 99.8, 76.1, 75.1, 71.8, 32.8, 29.7,
22.5, 13.9; IR (KBr) m = 3482, 2956, 1652, 1456, 1175,
1034 cmꢀ1; MS (EI) m/z (%): 459 (M+ + 1, 31.3), 458
(M+, 44.6), 362 (100.0). This compound was submitted
to next step without further characterization.
3.2.2. Synthesis of 3,7-dimethyl-2,3,4,6,7,8-hexahydro-
benzo[1,2b:5,4b0]dipyran (8b)
A solution of 6b (145 mg, 0.309 mmol) and 9-BBN
(2.3 mL, 0.32 M solution in THF, 0.742 mmol) in
THF (2 mL) was stirred at r.t. for 11 h. Then the mix-
ture was treated with PdCl2(dppf) (23 mg, 10 mol%)
and aqueous NaOH (0.31 mL of 3 M solution, 0.93
mmol) and stirred under reflux for 23 h to give 8b (46
mg, 68%) as a white solid, m.p.: 106 ꢁC (petroleum
ether); 1H NMR (300 MHz, CDCl3) d 6.67 (s, 1H),
6.28 (s, 1H), 4.16–4.07 (m, 2H), 3.62 (t, J = 9.90 Hz,
2H), 2.72 (dd, J = 15.75 and 3.55 Hz, 2H), 2.40–2.26
(m, 2H), 2.19–2.02 (m, 2H), 1.02 (d, J = 6.80 Hz, 6H);
IR (KBr) m = 2959, 1625, 1505, 1159, 1126 cmꢀ1; MS
(EI) m/z (%): 219 (M+ + 1, 26.0), 218 (M+, 100.0). Anal.
Calc. for C14H18O2: C, 77.03; H, 8.31. Found: C, 76.98;
H, 8.28.
3.1.10. Synthesis of 1,3-diiodo-4-(allyloxy)-6-(20-butylal-
lyloxy)benzene (6d)
The reaction of 7 (0.611 g, 1.33 mmol), Na2CO3 (0.57
g, 5.32 mmol), and allyl bromide (2a) (0.46 mL, 0.65 g,
5.34 mmol) in DMF (15 mL) afforded 6d (606 mg, 92%)
as a colorless oil; 1H NMR (300 MHz, CDCl3) d 8.05 (s,
1H), 6.35 (s, 1H), 6.10–5.94 (m, 1H), 5.50 (dq, J = 17.25
and 3.20 Hz, 1H), 5.32 (dq, J = 10.55 and 3.20 Hz, 1H),

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S. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 5389–5395
3.2.3. Synthesis of 3,7-dibutyl-2,3,4,6,7,8-hexahydro-
benzo[1,2b:5,4b0]dipyran (8c)
THF (2 mL) was stirred at r.t. for 11 h. Then the mix-
ture was treated with PdCl2(dppf) (21 mg, 10 mol%)
and aqueous NaOH (0.28 mL of 3 M solution, 0.84
mmol) and stirred under reflux for 23 h to give 9b (31
mg, 51%) as a white solid; m.p.: 165 ꢁC (petroleum
ether); 1H NMR (300 MHz, CDCl3) d 6.48 (s, 2H),
4.15–4.06 (m, 2H), 3.61 (t, J = 9.65 Hz, 2H), 2.82–2.70
(m, 2H), 2.43–2.30 (m, 2H), 2.19–2.02 (m, 2H), 1.00
(d, J = 6.70 Hz, 6H); 13C NMR (75 MHz, CDCl3)
d 147.9, 120.8, 116.3, 71.7, 33.1, 27.3, 17.0; IR (KBr)
m = 2957, 1504, 1422, 1035 cmꢀ1; MS (EI) m/z (%):
219 (M+ + 1, 16.8), 218 (M+, 100.0). Anal. Calc. for
C14H18O2: C, 77.03; H, 8.31. Found: C, 76.76; H, 8.20.
A solution of 6c (160 mg, 0.289 mmol) and 9-BBN
(2.2 mL, 0.32 M solution in THF, 0.694 mmol) in
THF (2 mL) was stirred at r.t. for 9 h. Then the mixture
was treated with PdCl2(dppf) (21 mg, 10 mol%) and
aqueous NaOH (0.29 mL of 3 M solution, 0.87 mmol)
and stirred under reflux for 23 h to give 8c (54 mg,
1
62%) as a colorless oil; H NMR (300 MHz, CDCl3) d
6.68 (s, 1H), 6.27 (s, 1H), 4.20–4.09 (m, 2H), 3.72–3.61
(m, 2H), 2.80–2.70 (m, 2H), 2.40–2.26 (m, 2H), 2.04–
1.86 (m, 2H), 1.47–1.18 (m, 12H), 0.98–0.80 (m, 6H);
IR (KBr) m = 2958, 1627, 1494, 1162, 1131 cmꢀ1; MS
(EI) m/z (%): 303 (M+ + 1, 28.3), 302 (M+, 100.0);
HRMS Calc. for C20H30O2: 302.22458. Found:
302.22187.
3.2.7. Synthesis of 3-methyl-2,3,4,7,8,9-hexahydrobenzo-
[1,2b:4,5b0]dipyran (9c)
A solution of 3c (120 mg, 0.331 mmol) and 9-BBN
(2.5 mL, 0.32 M solution in THF, 0.80 mmol) in THF
(2 mL) was stirred at r.t. for 11 h. Then the mixture
was treated with PdCl2(dppf) (24 mg, 10 mol%) and
aqueous NaOH (0.33 mL of 3 M solution, 0.99 mmol)
and stirred under reflux for 23 h to give 9c (30 mg,
45%) as a white solid; m.p.: 114 ꢁC (petroleum ether);
1H NMR (300 MHz, CDCl3) d 6.48 (d, J = 5.90 Hz,
2H), 4.18–4.06 (m, 3H), 3.61 (t, J = 10.0 Hz, 1H),
2.83–2.68 (m, 3H), 2.37 (dd, J = 15.90 and 9.60 Hz,
1H), 2.19–2.03 (m, 1H), 2.00–1.90 (m, 2H), 1.01 (d,
J = 6.70 Hz, 3H); 13C NMR (75 MHz, CDCl3) d
148.6, 148.0, 121.4, 121.1, 116.9, 116.6, 72.0, 66.6,
33.4, 27.5, 24.9, 22.8, 17.2; IR (KBr) m = 2934, 1504,
1422, 1059, 1028 cmꢀ1; MS (EI) m/z (%): 205
(M+ + 1, 17.4), 204 (M+, 100.0). HRMS Calc. for
C13H16O2: 204.11503. Found: 204.11127.
3.2.4. Synthesis of 3-butyl-2,3,4,6,7,8-hexahydrobenzo-
[1,2b:5,4b0]dipyran (8d)
A solution of 6d (154 mg, 0.309 mmol) and 9-BBN
(2.3 mL, 0.32 M solution in THF, 0.742 mmol) in
THF (2 mL) was stirred at r.t. for 9 h. Then the mixture
was treated with PdCl2(dppf) (23 mg, 10 mol%) and
aqueous NaOH (0.31 mL of 3 M solution, 0.93 mmol)
and stirred under reflux for 23 h to give 8d (50 mg,
1
66%) as a colorless oil; H NMR (300 MHz, CDCl3) d
6.69 (s, 1H), 6.27 (s, 1H), 4.19–4.08 (m, 3H), 3.68 (t,
J = 9.60 Hz, 1H), 2.81–2.63 (m, 3H), 2.40–2.26 (m,
1H), 2.02–1.90 (m, 3H), 1.43–1.20 (m, 6H), 0.97–0.85
(m, 3H); IR (KBr) m = 2961, 1630, 1159, 1094 cmꢀ1
;
MS (EI) m/z (%): 247 (M+ + 1, 20.4), 246 (M+, 100.0);
HRMS Calc. for C16H22O2: 246.16198. Found:
246.16481.
3.2.5. Synthesis of 2,3,4,7,8,9-hexahydrobenzo[1,2b:4,
5b0]dipyran (9a)
3.2.8. Synthesis of dodecahydrotriphenylene (11)
A solution of 10 (120 mg, 0.252 mmol) and 9-BBN
(2.8 mL, 0.32 M solution in THF, 0.896 mmol) in
THF (2 mL) was stirred at r.t. for 11 h. Then the mix-
ture was treated with PdCl2(dppf) (20 mg, 10 mol%)
and aqueous NaOH (0.3 mL of 3 M solution, 0.90
mmol) and stirred under reflux for 23 h to give 11 (21
mg, 35%) as a white solid; m.p.: 231–232 ꢁC (petroleum
ether) (lit. [11], m.p.: 232 ꢁC (petroleum ether)); 1H
NMR (300 MHz, CDCl3) d 2.80–2.50 (m, 12H), 2.00–
1.70 (m, 12H); 13C NMR (75 MHz, CDCl3) d 132.6,
26.8, 23.0; IR (KBr) m = 2917, 1432 cmꢀ1; MS (EI)
m/z (%): 241 (M+ + 1, 12.0), 240 (M+, 100.00). Anal.
Calc. for C18H24: C, 89.94; H, 10.06. Found: C, 89.60;
H, 10.05.
A solution of 3a (110 mg, 0.316 mmol) and 9-BBN
(2.4 mL, 0.32 M solution in THF, 0.758 mmol) in
THF (2 mL) was stirred at r.t. for 9 h. Then the mixture
was treated with PdCl2(dppf) (22 mg, 10 mol%) and
aqueous NaOH (0.32 mL of 3 M solution, 0.96 mmol)
and stirred under reflux for 24 h to give 9a (30 mg,
50%) as a white solid; m.p.: 101–102 ꢁC (petroleum
ether) (lit. [1] m.p.: 104–106 ꢁC (ethyl acetate)); 1H
NMR (300 MHz, CDCl3) d 6.47 (s, 2H), 4.10 (t,
J = 4.91 Hz, 4H), 2.70 (t, J = 6.40 Hz, 4H), 2.10–1.80
(m, 4H); 13C NMR (75 MHz, CDCl3) d 148.3, 121.2,
116.6, 66.3, 24.7, 22.6; IR (KBr) m = 1504, 1262, 1062,
801 cmꢀ1; MS (EI) m/z (%): 191 (M+ + 1, 13.3), 190
(M+, 100.0); Anal. Calc. for C12H14O2: C, 75.76; H,
7.42. Found: C, 75.68; H, 7.24.
Acknowledgements
3.2.6. Synthesis of 3,8-dimethyl-2,3,4,7,8,9-hexahydro-
benzo[1,2b:4,5b0]dipyran (9b)
A solution of 3b (105 mg, 0.279 mmol) and 9-BBN
(2.1 mL, 0.32 M solution in THF, 0.672 mmol) in
Financial support from National NSF of China (No.
20172060), the Major State Basic Research Develop-
ment Program (Grant No. G2000077500), and Shanghai

S. Ma et al. / Journal of Organometallic Chemistry 690 (2005) 5389–5395
5395
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Municipal Committee of Science and Technology is
greatly appreciated.
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