Ti-catalyzed reactions of 4,4′-bis(trimethylsilyl)bicyclohexyl-2,2′-diene with various electrophiles

Article abstract of DOI:10.1016/j.tetlet.2008.05.072

Reductive disilylation (Li + Me₃SiCl - THF) of 1,3-cyclohexadiene led to 4,4′-bis(trimethylsilyl)bicyclohexyl-2,2′-diene (1). In the presence of TiCl₄ in dichloromethane, 1 reacted with some acyl chlorides, anhydrides, and aldehydes

Full text of DOI:10.1016/j.tetlet.2008.05.072

Tetrahedron Letters 49 (2008) 4630–4632
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Tetrahedron Letters
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Ti-catalyzed reactions of 4,40-bis(trimethylsilyl)bicyclohexyl-2,20-diene
with various electrophiles
Chahinez Aouf a, Douniazad El Abed a, Michel Giorgi b, Maurice Santelli a,
*
a Laboratoire de Synthèse Organique, UMR CNRS 6180, 13397 Marseille Cedex 20, France
b Spectropôle, Faculté des Sciences de St-Jérôme, Aix-Marseille Université, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France
a r t i c l e i n f o
a b s t r a c t
Reductive disilylation (Li + Me3SiCl ꢀ THF) of 1,3-cyclohexadiene led to 4,40-bis(trimethylsilyl)bicy-
clohexyl-2,20-diene (1). In the presence of TiCl4 in dichloromethane, 1 reacted with some acyl chlorides,
anhydrides, and aldehydes to give tricyclo[7.4.0.03,8]trideca-4,12-diene-2-yl derivatives.
Ó 2008 Published by Elsevier Ltd.
Article history:
Received 22 April 2008
Revised 14 May 2008
Accepted 14 May 2008
Available online 20 May 2008
Keywords:
Reductive silylation
1,3-Cyclohexadiene
Titanium tetrachloride
Electrophilic substitution
The bis-silylation of dienic or trienic hydrocarbons is a particu-
larly interesting transformation, which allows the simultaneous
creation of two new Si–C bonds. This reaction constitutes a conve-
nient route to obtain bis(silyl) unsaturated compounds that can
represent useful intermediates or can be used as building blocks
in organic synthesis. A very simple procedure is the reductive dis-
ilylation of 1,3-dienes by lithium and chlorotrimethylsilane giving
rise to a mixture of 1,4-bis(trimethylsilyl)-2-butene derivatives
and 1,8-bis(trimethylsilyl)-2,6-octadiene derivatives.1
H
Me3Si
SiMe3
1, 48%
H
SiMe3
+ Li
THF
+
Me3SiCl
+
SiMe3
SiMe3
3, 8%
SiMe3
In previous work,2 we have obtained stereoselectively unsatu-
rated disilanes with 1,3,5-cycloheptatriene. We have now applied
these results to the reaction of 1,3-cyclohexadiene. In presence of
lithium and chlorotrimethylsilane in THF, cyclohexadiene led to a
mixture of 4,40-bis(trimethylsilyl)bicyclohexyl-2,20-diene (1), 1,4-
bis(trimethylsilyl)cyclohex-2-ene (2), and 3,4-bis(trimethylsilyl)-
cyclohex-1-ene (3).3 After the separation by distillation 1 appeared
as a mixture of isomers (Scheme 1).4
To explain the formation of 1–3, we can expect a sequence of
reactions involving the initial formation of the anion radical 4
which is trapped by trimethylchlorosilane to give allylic radical 5
(further reduction of 5 into allylic anion and its trapping by tri-
methylchlorosilane led to 2 and 3). The stereoselectivity of the
dimerization of 5 comes from a transition state corresponding to
an unlike relative approach5 with an anti geometry indifferent to
the uncontrolled centers bearing trimethylsilyl groups. Transition
2, 22%
Scheme 1. Synthesis of 4,40-bis(trimethylsilyl)bicyclohexyl-2,20-diene (1).
Li
Me3SiCl
−
( )
Me3Si
Li(+)
4
5
-face
H
Re
approach
ul-
Me3Si
1
H
SiMe3
-face
Si
Scheme 2. Formation of the allylic radical 5 and its dimerization into 1.
state with a possibility of large molecular orbitals overlap did not
occur (Scheme 2).
* Corresponding author. Tel.: +33 4 91288825; fax: +33 4 91289112.
E-mail address: m.santelli@univ-cezanne.fr (M. Santelli).
0040-4039/$ - see front matter Ó 2008 Published by Elsevier Ltd.
doi:10.1016/j.tetlet.2008.05.072

C. Aouf et al. / Tetrahedron Letters 49 (2008) 4630–4632
4631
H
TiCl4 (1 eq)
H
H
H
TiCl4 (1 eq)
CH2Cl2
7
1
+
+
RCHO
O
H
H
O
+
+
CH2Cl2
R
1
H
H
H
Me
Cl
−60 °C
12
12a, 55%; 7, 18%
−
60 °C
O
SiMe3
a, RCHO =
Me
6
7
, 12%
, 50%
H
O
Scheme 3. Reaction of 1 with the acetyl chloride.
b
12b 7
, 59%; , 10%
, RCHO =
MeO
In the aim to reveal the reactivity of 1 toward electrophilic re-
agents, this disilyldiene has been added in the presence of TiCl4
to various compounds. For example, acetyl chloride gave rise to
silylated monoketone 6 and the bicyclohexyl-3,30-diene 7 (Scheme
3).6
H
O
H
c
12c
7
, RCHO =
, 41%; , 12%
TiCl4 (2 eq)
In contrast, addition to benzoyl chloride, oxalyl chloride, triflu-
oroacetic anhydride, and acetic anhydride occurred with cycliza-
tion giving rise to the tricyclo[7.4.0.03,8]trideca-4,12-diene-2-yl
skeleton in fair yields except for the last which required 2 equiv
TiCl4. In each case only one stereoisomer has been obtained
(Scheme 4).7
In a similar manner, some aromatic aldehydes underwent a
double alkylation leading, again, to the tricyclo[7.4.0.03,8]trideca-
4,12-diene-2-yl skeleton in fair yields (Scheme 5).8
O
12d
7
d, RCHO =
, 62%; , 3%
H
TiCl4 (2 eq)
Scheme 5. Reaction of 1 with aromatic aldehydes.
Br
With o-bromobenzaldehyde, the carbonyl group was too hin-
dered and also electron-poor to favor the double alkylation, and
the desilylated alcohol 13 (two isomers) was the only product with
7 (Scheme 6).9
Pleasingly, 12d was crystallized and X-ray crystallographic
analysis clearly showed that the five stereogenic centers of the
cyclopentane ring were controlled (Fig. 1). For 1, as the chirality
around the C(1)–C(1)0 bond cannot be modified in the course of
the reaction, we conclude that its structure is (R*,S*). Consequently,
as 1 is a mixture of three isomers (1.5:1:1), the two stereogenic
centers bearing the trimethylsilyl groups were uncontrolled
(Scheme 2).
Br
TiCl4 (1 eq)
O
1
+
+
7
, 4%
H
H
OH
CH2Cl2
H
−60 ˚C
13
, 52%
Scheme 6. Reaction of 1 with o-bromobenzaldehyde.
C11
C12
C10
C9
H
C23
C22
TiCl4 (1 eq)
O
OH
H
H
C20
C21
1
1
1
1
+
+
7
, 3%
C13
CH2Cl2
C8
C7
Ph
Ph
O
Cl
H
C19
−60 °C
C14
8, 58%
C1
C16
C15
C2
C6
C18
C17
H
H
O
TiCl4 (1 eq)
H
H
C3
+
+
7, 9%
O
CH2Cl2
C5
Cl
Cl
C4
−60 °C
9, 60%
Figure 1. ORTEP drawing for 12d. Non-hydrogen atoms are drawn with 50% pro-
bability thermal ellipsoids.10
O
O
O
H
CF3
CF3
TiCl4 (1 eq)
OH
H
H
+
+
+
7
, 3%
All the electrophilic substitution reactions afforded bicy-
clohexyl-3,30-diene 7 among other products.11 Consequently, 1
was treated with TiCl4 at low temperature for 72 h. After usual
work-up, 7 was isolated in 35% yield (Scheme 7). Moreover, when
the reactive mixture was poured into cold anhydrous K2CO3 solu-
tion in deuterium oxide, we have isolated the isotopomere 7d2.
The NMR data showed that two methylene groups were deuter-
ated.12 As allylsilane moiety is stable in aqueous basic medium,
the observed protolysis can involve a metathesis (transmetalation
reaction) of the allylsilane unit to an allyltrichlorotitane which is
easily protolysed in basic medium (titanium presents a strong oxo-
philic character).13
CH2Cl2
CF3
H
−60 °C
10
, 53%
O
O
O
H
CH3
CH3
TiCl4 (2 eq)
CH2Cl2
OH
H
+
7, 43%
H
CH3
H
−
60 °C
11, 15%
Scheme 4. Reaction of 1 with acyl chlorides and anhydrides.

4632
C. Aouf et al. / Tetrahedron Letters 49 (2008) 4630–4632
2-Trifluoromethyltricyclo[7.4.0.03,8]trideca-4,12-dien-2-ol (10), colorless oil,
1H NMR (300 MHz, CDCl3) d 1.08 (d, J = 5.1 Hz, 1H), 1.12 (dd, J = 12.2, 5.1 Hz,
1H), 1.60–1.54 (m, 2H), 1.89–1.83 (m, 2H), 2.21–2.15 (m, 4H), 2.61 (d,
J = 9.7 Hz, 1H), 2.72 (br s, 1H), 5.83 (br s, 4H); 13C NMR (75 MHz, CDCl3) d 19.9
(t), 23.6 (t), 24.0 (t), 26.8 (t), 39.0 (d), 41.6 (d), 44.6 (d), 50.7 (d), 82.1 (d,
TiCl4 (2 eq)
TiCl4 (2 eq) K2CO3
D
D
1
7
1
H
H
CH2Cl2
CH2Cl2
D2O
J
2 (CF) = 26.4 Hz), 123.7 (d), 124.0 (d), 124.3 (q, 1 (CF)
(d).
J
= 311.9 Hz), 129.2 (d), 133.2
35%
−60 °C
−60 °C
7d
2, 35%
2-Methyltricyclo[7.4.0.03,8]trideca-4,12-dien-2-ol (11), colorless oil, 1H NMR
(300 MHz, CDCl3) d 0.90 (dt, J = 6.9, 3.4 Hz, 1H), 1.16 (s, 3H), 1.26–1.18 (m, 2H),
1.65–1.48 (m, 4H), 2.20–2.02 (m, 3H), 2.38–2.29 (m, 2H), 5.61 (1/2 AB, q,
J = 10.2, 3.3 Hz, 1H), 5.71 (1/2 AB, t, J = 10.0, 3.1 Hz, 1H), 5.85 (1/2 AB, q, J = 9.9,
2.0 Hz, 1H), 5.98 (m, 1H); 13C NMR (75 MHz, CDCl3) d 14.2 (q), 24.1 (t), 26.8 (t),
29.5 (t), 32.0 (t), 38.8 (d), 42.1 (d), 50.1 (d), 51.4 (d), 78.7 (s), 125.2 (d), 127.3
(d), 127.9 (d), 130.9 (d).
Scheme 7. Titanium-mediated protolysis of 1.
8. 2-p-Tolyltricyclo[7.4.0.03,8]trideca-4,12-diene (12a), colorless oil, 1H NMR
(300 MHz, CDCl3) d 0.89 (t, J = 5.0 Hz, 1H), 1.27 (s, 3H), 1.73–1.44 (m, 5H),
2.04–2.01 (m, 3H), 2.20–2.18 (m, 2H), 2.33 (d, J = 3.0 Hz, 2H), 5.59 (br s, 2H),
5.69–5.66 (m, 2H), 7.03 (d, J = 7.9 Hz, 2H), 7.10, (d, J = 7.9 Hz, 2H); 13C NMR
(75 MHz, CDCl3), d = 21.2 (q), 22.8 (t), 23.8 (t), 24.0 (t), 27.2 (t), 39.7 (d), 41.8
(d), 45.3 (d), 45.7 (d), 53.0 (d), 127.2 (d), 127.5 (d), 127.8 (d), 128.7 (d, 2C),
129.2 (d), 129.5 (d, 2C), 135.3 (s), 138.4 (s).
In conclusion, we have described a direct way to the synthesis
of tricyclic compounds from 1,3-cyclohexadiene. Previous results
in this area used elaborate precursors.14 Moreover, a good control
of the stereochemistry is observed and these results may be ap-
plied to the synthesis of more complex products.
2-p-Anisyltricyclo[7.4.0.03,8]trideca-4,12-diene (12b), colorless oil, 1H NMR
(300 MHz, CDCl3) d 1.22 (t, J = 7.2 Hz, 2H), 1.43–1.40 (m, 2H), 1.63–1.56 (m,
2H), 2.02–1.86 (m, 5 H), 2.18–2.16 (m, 2H), 3.78 (s, 3H), 5.57 (br s, 2H), 5.67 (br
s, 2H), 6.80 (d, J = 8.1 Hz, 1H), 6.86 (d, J = 8.8 Hz, 1H), 7.04 (d, J = 8.3 Hz, 1H),
7.16 (d, J = 8.5 Hz, 1H); 13C NMR (75 MHz, CDCl3), d = 21.4 (t), 22.6 (t), 23.7 (t),
26.6 (t), 39.7 (d), 40.7 (d), 45.1 (d), 46.8 (d), 50.5 (d), 55.4 (q), 113.4 (d, 2C),
113.9 (d, 2C), 128.7 (d, 2C), 130.4 (d, 2C), 136.1 (s), 158.1 (s).
Acknowledgments
C.A. is grateful to the ‘Association des Femmes Diplomées de
l’Université’ for a Grant (‘bourse Hélène Delavaud’). This work
has been financially supported by the CNRS and the Ministère de
l’Education Nationale. We thank the Centre Régional de Mesures Phy-
siques de l’Ouest, (Rennes, Fr) for analysis.
2-(1-Naphthyl)tricyclo[7.4.0.03,8]trideca-4,12-diene (12c), colorless oil, two
isomers (2.3:1), 1H NMR (300 MHz, CDCl3) d 1.28–1.23 (m, 1H), 1.78–1.72
(m, 3H), 2.5–2.0 (m, 5H), 2.99–2.91 (m, 2H), 3.40–3.35 (m, 1H), 3.74 (t,
J = 11.7 Hz, 1H), 5.85–5.50 (m, 4H), 7.34 (d, J = 7.2 Hz, 1H), 7.55–7.45 (m, 2H),
7.74 (d, J = 8.1 Hz, 1H), 7.90 (dd, J = 4.0, 2.3 Hz, 1H), 8.14 (d, J = 8.0 Hz, 1H), 8.25
(d, J = 8.4 Hz, 1H); 13C NMR (75 MHz, CDCl3), d = 22.9 (t), 23.7 (t), 24.1 (t), 27.3
(t), 39.5 (d), 41.3 (d), 41.5 (d), 45.7 (d), 48.6 (d), 124.0 (d), 124.3 (d), 125.4 (d),
125.6 (d), 126.0 (d), 126.5 (d), 128.2 (d, 2C), 128.4 (d), 128.9 (d), 129.3 (d),
133.5 (s), 133.9 (s), 137.4 (s).
References and notes
1. (a) Tubul, A.; Santelli, M. Tetrahedron 1988, 44, 3975–3982; (b) Aouf, C.; El
Abed, D.; Ibrahim-Ouali, M.; Giorgi, M.; Santelli, M. Eur. J. Org. Chem. 2007,
3115–3121.
2. Aouf, C.; El Abed, D.; Giorgi, M.; Santelli, M. Tetrahedron Lett. 2007, 48, 4969–
4972.
3. For a previous synthesis of products 2 and 3, see: (a) Dunoguès, J.; Calas, R.;
Dedier, J.; Pisciotti, F.; Lapouyade, P. J. Organomet. Chem. 1970, 25, 51–55; (b)
Eaborn, C.; Jackson, R. A.; Pearce, R. J. Chem. Soc., Perkin Trans. 1 1974, 2055–
2061.
2-(2-Naphthyl)tricyclo[7.4.0.03,8]trideca-4,12-diene (12d), white crystals, mp
148 °C, 1H NMR (300 MHz, CDCl3) d 1.22 (t, J = 7.0 Hz, 1H), 1.30 (qd, J = 12.0,
4.6 Hz, 1H), 1.80–1.60 (m, 3H), 1.96–1.85 (m, 2H), 2.25–2.18 (m, 2H), 2.32
(sext. J = 6.1 Hz, 1H), 2.64 (br. t, J = 8.0 Hz, 1H), 3.08 (m, 2H), 4.98 (d, J = 10.2 Hz,
1H), 5.59 (br s, 1H), 5.69–5.65 (m, 2H), 7.30 (dd, J = 7.0, 1.5 Hz, 2H), 7.44–7.41
(m, 2H), 7.59 (s, 1H), 7.86–7.74 (m, 2H); 13C NMR (75 MHz, CDCl3),d = 22.6 (t),
23.8 (t), 24.1 (t), 27.4 (t), 39.8 (d), 42.0 (d), 45.2 (d), 45.9 (d), 53.7 (d), 125.2 (d),
125.8 (d), 127.3 (d), 127.6 (d, 2C), 127.8 (d, 2C), 128.4 (d), 129.3 (d), 129.4 (d,
2C), 132.3 (s), 133.6 (s), 139.3 (s).
4. 4,40-Bis(trimethylsilyl)bicyclohexyl-2,20-diene (1), colorless oil, bp 135–145 °C
(0.2 mm Hg), 1H NMR (300 MHz, CDCl3) d 0.03–0.01 (m, 18H), 1.43–1.30 (m,
8H), 1.80–1.55 (m, 2H), 2.07–2.06 (m, 2H), 5.68–5.50 (m, 4H); 13C NMR
(75 MHz, CDCl3), major isomer, d = ꢀ3.3 (q), 23.8 (t), 26.4 (d), 26.8 (t), 40.3 (d),
128.1 (d), 128.4 (d), other isomers, d = ꢀ1.9 (q), 22.8 (t), 23.8 (t), 26.5 (d), 26.6
(t), 27.1 (d), 38.2 (d), 39.8 (d), 128.8 (d), 129.1 (d), 129.2 (d), 129.4 (d), 129.5
(d); MS: m/z (%) = 306 (M+, 4), 153 (25), 79 (28), 73 (100), 45 (20).
Compound 2, colorless oil, bp 50 °C (0.2 mm Hg), 1H NMR (300 MHz, CDCl3) d
ꢀ0.027, ꢀ0.016 (s, 18H), 1.82–1.30 (m, 6H), 5.60 (s, 2H); 13C NMR (75 MHz,
CDCl3), major isomer, d = ꢀ2.5 (q), 23.5 (t), 26.6 (d), 126.0 (d); minor isomer,
d = ꢀ3.2 (q), 24.6 (t), 26.1 (d), 126.5 (d); MS: m/z (%) = 226 (M+, 80), 211 (50),
152 (40), 78 (41), 73 (100), 45 (30). 3, 13C NMR (75 MHz, CDCl3) d = ꢀ2.1 (q),
20.7 (d), 22.1 (t), 23.8 (t), 26.9 (d), 124.3 (d), 128.2 (d).
5. Seebach, D.; Prelog, V. Angew. Chem., Int. Ed. Engl. 1982, 21, 654–660.
6. A 50 mL two-necked flask equipped with a thermometer, a stopcock to a
rubber balloon filled with argon and a magnetic stirring bar was charged with
anhydrous CH2Cl2 (25 mL). The solution was cooled to ꢀ60 °C and TiCl4 was
introduced (0.5 mL, 4.4 mmol). Then a solution of acetyl chloride (0.3 mL,
4.4 mmol) in CH2Cl2 (2 mL) was slowly added. The solution was cooled to
ꢀ90 °C and 1 (2 g, 6.5 mmol) in CH2Cl2 (5 mL) was added. After 2 h of stirring,
the solution was allowed to warm to ꢀ60 °C for 20 h. The reaction mixture was
poured onto ice and NH4Cl. After the common work-up procedure, the crude
product was flash chromatographed on silica gel eluting with petroleum ether/
ether (90:10) to give 6 (607 mg, 2.2 mmol). Compound 6, colorless oil, 1H NMR
(300 MHz, CDCl3) d ꢀ0.07 (s, 9H), 1.22 (br s, 2H), 1.38 (m, 3H), 160–1.55 (m,
2H), 2.02–1.99 (m, 5H), 2.14 (s, 3H), 5.62 (br s, 2H), 5.81 (br s, 2H); 13C NMR
(75 MHz, CDCl3) d ꢀ3.4 (q), 23.5 (t), 23.8 (t), 25.3 (d), 26.2 (t), 26.3 (d), 28.5 (t),
39.8 (d), 40.0 (d), 49.0 (q), 124.3 (d), 124.7 (d), 126.7 (d), 134.0 (d), 209.3 (s).
All new compounds gave correct elemental analysis.
9. Compound 13. Colorless oil, two isomers (4:1), 1H NMR (300 MHz, CDCl3) d
1.79–1.68 (m, 6H), 2.07–2.01 (m, 7H), 2.66 (br s, 1H), 5.18 (br s, 1H), 5.42 (t,
J = 11.0 Hz, 1H), 5.68 (m, 2H), 5.99 (dm, J = 8.0 Hz, 1H), 7.10 (t, J = 7.5 Hz, 1H),
7.32 (t, J = 7.5 Hz, 1H), 7.49 (m, 2H); 13C NMR (75 MHz, CDCl3), major isomer
d = 22.3 (t), 24.3 (t), 26.3 (t), 27.7 (t), 30.7 (t), 33.9 (d), 40.8 (d), 42.6 (d), 74.0 (d),
121.9 (s), 124.1 (d), 127.13 (d), 127.2 (d), 127.5 (d), 128.4 (d), 128.6 (d), 132.7
(d), 133.0 (d), 142.5 (s); minor isomer d = 21.9 (t), 24.1 (t), 25.5 (t), 28.3 (t), 34.0
(d), 40.8 (d), 42.5 (d), 73.0 (d), 121.6 (s), 124.2 (d), 126.9 (d), 127.17 (d), 127.3
(d), 128.5 (d), 128.7 (d), 132.9 (d), 133.1 (d), 142.7 (s).
10. 12d. Crystal data and structure refinement. CCDC-680455 contains the
supplementary crystallographic data. These data can be obtained free of
charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(internat.) +44-1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk]. Formula:
C
23H24
;
Mw
:
300.42; crystal color: colorless; crystal size/mm3:
0.4 ꢁ 0.2 ꢁ 0.15; crystal system: monoclinic; space group: P21/c; a/Å:
12.3730(3); b/Å: 6.1630(1); c/Å: 23.8020(7); b/°: 110.9350(9); V/Å3:
1695.20(7); Z: 4; Dc/g cmꢀ3: 1.094;
l
(Mo K
a
)/cmꢀ1: 1.178; No. of unique
data: 3188; No. parameters refined: 208; No. refl. in refinement: (3188;
F
2 > 4 F2: 2451); R: 0.0676 [F2 > 4 F2]; wR: 0.1833 [F2 > 4 F2] (w = 1/
r r r
[
r
2(F2o) + (0.1036P)2 + 0.5747P]) where P = (Fo2 þ 2F2c )/3; goodness of fit:
1.133; residual fourier/e Åꢀ3: ꢀ0.272; 0.271.
11. Compound 7, colorless oil, 1H NMR (300 MHz, CDCl3) d 1.25–1.18 (m, 2H),
1.41–1.26 (m, 2H), 1.81–1.75 (m, 4H), 2.06–1.82 (m, 6H), 5.65 (br s, 4H); 13C
NMR (75 MHz, CDCl3) d 25.9 (t), 26.2 (t), 29.4 (t), 38.8 (d), 127.0 (d), 127.17 (d);
MS: m/z (%) = 162 (M+, 39), 134 (50), 119 (26), 105 (15), 91 (38), 79 (100), 67
(25), 53 (20).
7. 2-Phenyltricyclo[7.4.0.03,8]trideca-4,12-diene-2-ol (8), yellow oil, 1H NMR
(300 MHz, CDCl3) d 1.59–1.51 (m, 3H), 1.80–1.70 (m, 2H), 2.09–1.99 (m, 4H),
2.20 (br s, 1H), 2.49 (d, m, J = 9.4 Hz, 1H), 3.05 (d, sext, J = 9.6, 2.1 Hz, 1H), 5.57–
5.47 (m, 2H), 5.68 (1/2 AB, q, J = 9.8, 3.2 Hz, 1H), 6.19 (dddd, J = 9.7, 5.01, 3.94,
1.75 Hz, 1H), 7.25 (d, J = 7.2 Hz, 1H), 7.35 (dd, J = 8.1, 7.2 Hz, 2H), 7.51 (dd,
J = 8.1, 1.0 Hz, 2H); 13C NMR (75 MHz, CDCl3) d 22.2 (t), 25.5 (t), 26.9 (t), 27.1
(t), 39.9 (d), 44.1 (d), 52.2 (d), 54.8 (d), 81.0 (s), 124.4 (d), 125.2 (d), 125.5 (d,
2C), 126.6 (d), 128.2 (d, 2C), 130.2 (d), 134.3 (d), 145.5 (s).
12. Compound 7d2, colorless oil, 1H NMR (300 MHz, CDCl3) d 2.06–1.80 (m, 4H);
13C NMR (75 MHz, CDCl3) d 29.4 (m) with reduced intensity; 2H NMR d 1.86
(W1/2 = 6.08 Hz; decoupled, W1/2 = 3.56 Hz); MS: m/z (%) = 164 (M+, 30), 134
(40), 121 (18), 106 (9), 92 (26), 80 (100), 67 (17), 54 (18); HRMS calcd for
C
12H16D2, 164.1534; found, 164.1545.
13. Allison, J.; Ridge, D. P. J. Am. Chem. Soc. 1978, 100, 163–169.
14. The tricyclo[7.4.0.03,8]tridecane constitutes the skeleton of gibberellanes, see:
(a) Ho, T.-L. Carbocycle Construction in Terpene Synthesis; VCH Publisher:
Weinheim, 1988; (b) Pinto, A. C.; Epifanio, R. de A.; Camargo, W. Tetrahedron
1993, 49, 5039–5046; For examples of synthesis, see: (a) Jamart-Grégoire, B.;
Brosse, N.; Ianelli, S.; Nardelli, M.; Caubère, P. J. Org. Chem. 1993, 58, 4572–
4578; (b) Denmark, S. E.; Wallace, M. A.; Walker, C. B., Jr. J. Org. Chem. 1990, 55,
5543–5545.
Tricyclo[7.4.0.03,8]trideca-4,12-dien-2-one (9), colorless oil, 1H NMR (300 MHz,
CDCl3) d 1.23 (br s, 2H), 1.60–1.55 (m, 5H), 2.01–1.96 (m, 5H), 5.64 (br s, 2H),
5.90–5.82 (m, 2H); 13C NMR (75 MHz, CDCl3) d 22.8 (t), 25.9 (t), 26.2 (t), 29.0
(t), 38.1 (d), 38.4 (d), 39.8 (d), 46.5 (d), 124.3 (d), 126.8 (d), 127.2 (d), 138.9 (d),
211.8 (s); MS: m/z (%) = 188 (M+, 25), 170 (33), 79 (100), 51 (20).