4924
M. Ghandi, M. Shahidzadeh / Journal of Organometallic Chemistry 691 (2006) 4918–4925
1
3
with a GCMS-QP 1000EX, Shimadzu. Organocadmium
reactions were conducted in oven-dried glassware under
nitrogen stream. Diethyl ether and tetrahydrofuran
(syn & anti), 0.91 (t, 3H, CH3) C NMR (CDCl , d): 210.6,
3
207.8 (C@O, C-3, C-6), 137.5, 137.1 (C-9, C-10), 53.2, 52.8,
52.3, 50.9 (C-2, C-4, C-5, C-7), 49.2 (C-11), 48.1 (C-1), 42.8
(C-8), 29.7 (CH , aliphatic), 22.1 (CH , aliphatic), 14.2
CH , aliphatic). IR (liquid film, cm : 3100, 2950, 1710
(C@O, non-conjugate), 1420,1180. MS (EI, m/z (%)) :
(
THF) were distilled over Na-benzophenone before use.
2
2
À1
(
3
1
4.2. General procedure for the addition of dialkylcadmium
reagent to benzoquinone
2
152 (65%, 5-propyl-2,3-cyclohex-2-ene-1,4-dione system
obtained from decomposition of 6b in the heated inlet sys-
The organocadmium reagent solution (0.02 mol) in
tem),123 (100%,152-C H ), 81(16%), 66 (21%, cyclopenta-
2
5
1
00 ml of diethyl ether [12] was cooled to À10 ꢁC and a
diene system).
1
solution of benzoquinone (0.01 mol) in THF (150 ml) was
added to cadmium reagent through a dropping funnel.
The reaction mixture was stirred for 1 h. After hydrolysis
with saturated aqueous ammonium chloride, the mixture
was extracted with 2 · 50 ml of chloroform. The organic
layer was washed with water (2 · 50 ml), and dried over
anhydrous Na SO . The crude product was purified by
Compound 6c: H NMR (CDCl , d): 6.2 (t, 2H, 1.5 Hz,
9-H, 10-H), 3.0–3.3 (m, 2H, 1-H, 8-H), 2.1–2.7 (m, 4H, 2-
H, 4-H, 5-H, 7-H), 1.13–1.4 (m, 6H, 3CH (aliphatic),11-H
(syn & anti), 0.97 (t, 3H, CH3). C NMR CDCl , d): 211.7,
209.8 (C@O, C-3, C-6), 136.7,136.5 (C-9, C-10), 52.3, 50.9,
49.8, 49.0 (C-2, C-4, C-5, C-7), 48.0 (C-11), 47.6 (C-1), 43.3
(C-8), 29.5 (CH , aliphatic), 28.8 (CH , aliphatic), 22.6
3
2
1
3
3
2
4
2
2
PLTC (silica gel) eluting with chloroform–hexane (9:1)
for benzoquinone and chloroform–hexane (1:1) for 2,6-
dimethylbenzoqinone.
(CH , aliphatic), 14.1 (CH , aliphatic). IR (liquid film,
2
À1
3
cm ): 3110, 2960, 1715 (C@O, non-conjugate), 1440,
1
2
1160, 885. MS (EI, m/z (%)) : 166 (57%, 5-butyl-2,3-cyclo-
hex-2-ene-1,4-dione system obtained from decomposition
of 6c in the heated inlet system), 123 (100%, 166-C H ),
4
.3. General procedure for the preparation of 6
3
9
81 (20%), 66 (25%, cyclopentadiene system).
A solution of the organocadmium reagent (0.02 mol) in
1
00 ml of diethyl ether was cooled to À10 ꢁC. To this was
4.4. General procedure for the thermolysis of 6
added a solution of 5 (0.015 mol) in diethyl ether (50 ml)
through a dropping funnel. The reaction mixture was stir-
red for 3 h. After hydrolysis with saturated aqueous ammo-
nium chloride (50 ml), the mixture was extracted with
methylene chloride (2 · 50 ml). The organic layer was
washed with water (50 ml), and dried over anhydrous
Na SO . The solvent was removed under reduced pressure
A round bottom flask (25 ml) containing 10 g of 6
attached to the distillation head, an air condenser (15 cm)
and a 25 ml receiver was connected to a vacuum pump.
The distillation flask was placed in an oil bath and was
heated to 180 ꢁC while magnetic stirring rapidly. Com-
pound 3 was collected at 20 mm Hg as a pale yellow oil.
2
4
and the crude product was purified by PTLC (silica gel)
eluting with chloroform–hexane (4:1). The product was
obtained as a pale yellow oil. The spectral data of resul-
5. Method of calculation
tants are as follow:
Compound 6a: H NMR (CDCl , d): 6.3 (t, 2H,1.6 Hz, 9-
H, 10-H), 3.0–3.4 (m, 2H, 1-H, 8-H), 2.1–2.7 (m, 4H, 2-H, 4-
H, 5-H, 7-H), 1.1–1.4 (m, 4H, CH (aliphatic), 11-H (syn &
anti)), 0.87 (t, 3H, CH3). C NMR (CDCl , d): 193.1, 191.2
The structure of compounds was built by chemdraw,
version 8, and was saved as MOPAC input files by chem3D
for PM3 calculation. All PM5 calculations were done by
WINMOPAC v.3.5.
1
3
2
1
3
3
(
C@O, C-3, C-6), 135.9, 135.7 (C-9, C-10), 51.5, 50.7, 50.1,
Acknowledgement
4
9.1 (C-2, C-4, C-5, C-7), 48.7 (C-11), 47.5 (C-1), 43.5 (C-
8
), 23.6 (CH , aliphatic), 11.2 (CH , aliphatic). IR (liquid
We are indebted to the University of Tehran for the
financial support of this work.
2
3
À1
film, cm ): 3100, 2960, 1710 (C@O, non-conjugate), 1420,
1
2
8
80. MS (EI, m/z (%)) : 138 (59%, 5-ethyl-2,3-cyclohex-2-
ene-1,4-dione system obtained from decomposition of 6a
References
2
in the heated inlet system), 123 (100%,138-CH ), 81
3
[
1] (a) D.A. Shirley, Organic Reactions, vol. 8, Wiley, New York, 1954,
p. 28;
(
22%), 66 (17%, cyclopentadiene system).
1
Compound 6b: H NMR (CDCl , d): 6.3 (t, 2H, 1.6 Hz,
3
(
(
b) R.E. Lyle, J.L. Marshall, D.L. Comins, Tetrahedron Lett. 12
1977) 1015–1018;
9
-H, 10-H), 3.0–3.4 (m, 2H, 1-H, 8-H), 2.1–2.6 (m, 4H, 2-
H, 4-H, 5-H, 7-H), 1.1–1.4 (m, 6H, 2CH (aliphatic), 11-H
2
(c) F.A. Carry, R.J. Sundberg, Advanced Organic Chemistry, Part B,
Pelenum, New York, 1990, p. 392.
[
2] (a) P.M. Gocemen, G. Soussan, Bull. Soc. Chim. Fr. (1973) 562;
(b) A. Aponic, J.D. McKinely, J.C. Rabert, C.T. Wigal, J. Org.
Chem. 63 (1998) 2676.
1
Parent peaks of the 6a–c do not appear even in high resolution mass
spectra, because these compounds are decomposed to 5-alkyl-cyclohex-2-
ene-1,4-diones at high temperature.
[3] (a) M. Shahidzadeh, M. Ghandi, J. Organomet. Chem. 625 (2001)
108;
2
5-Alkyl-cyclohex-2-ene-1,4-dione is reduced to the corresponding
hydroquinone and subsequent fragmentation occurs [13].
(b) M. Shahidzadeh, Ph.D Thesis, University of Tehran, Iran, 2002.