Synthesis of polymethyl substituted [2.2]metaparacyclophanes and their Lewis-acid induced isomerisation to [2.2]metacyclophanes

Article abstract of DOI:10.3184/030823409X430185

The preparation of polymethyl substituted [2.2]metaparacyclophanes using sulfur method and the X-ray structure determination of 4,5,6,8,12,13,15,16- octamethyl[2.2]metaparacyclophane are described. AlCl₃-MeNO ₂-catalysed trans-tert-b

Full text of DOI:10.3184/030823409X430185

244 RESEARCH PAPER
APRILꢃꢀꢇꢅꢅ±ꢇꢅꢂ
JOURNAL OF CHEMICAL RESEARCH 2009
Synthesis of polymethyl substituted [2.2]metaparacyclophanes and their
Lewis-acid induced isomerisation to [2.2]metacyclophanes
Tomoe Shimizua, Katsuhiro Hitaa, Arjun Paudela, Junnji Tanakab and Takehiko Yamatoa,*
aDepartment of Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjo-machi 1, Saga 840-8502, Japan
bInstitute for Material Chemistry and Engineering, Kyushu University, 6-1, Kasugakoen, Kasuga 816-8580, Japan
The preparation of polymethyl substituted [2.2]metaparacyclophanes using sulfur method and the X-ray structure
determination of 4,5,6,8,12,13,15,16-octamethyl[2.2]metaparacyclophane are described. AlCl3-MeNO2-catalysed
trans-tert-butylation of 5-tert-butyl-8,12,13,15,16-pentamethyl[2.2]metaparacyclophane in benzene led to
isomerisation reaction to afford the strainless 8,12,13,14,16-pentamethyl[2.2]metacyclophane in 85% yield along
with tert-butylbenzene.
Keywords: metacyclophane, metaparacyclophane, Lewis-acid, isomerisation, strain
The meta-bridged benzene ring of [2.2]metaparacyclophane
(MPCP = metaparacyclophane) (1) has been shown to undergo
FRQIRUPDWLRQDOꢀÀLSSLQJꢁ±ꢂꢀwith a substantial energy barrier (ca.
20 kcal mol-1). According to X-ray crystallographic studies of
1,8 the deformations of benzene rings are similar to those of
the corresponding rings in para- and meta[2.2]cyclophanes,
with para- and meta-bridged rings bent in a boat- and a chair-
like form, respectively. The angle between the two aromatic
SODQHVꢀ GH¿QHGꢀ E\ꢀ WKHꢀ FDUERQꢀ DWRPVꢃꢀ ꢄꢃꢀ ꢅꢃꢀ ꢆꢀ DQGꢀ ꢂꢃꢀ RQꢀ RQHꢀ
hand, and 12, 13, 15 and 16, on the other, is about 13°. It
should be noted that the angle between the 11, 12, 16-plane
and 10, 11-bond vector (or between 13, 14, 15-plane and 1,
14-bond vector) is even larger than the analogous angle in
[2.2]paracyclophane. The para-bridged moiety of 1 is thus
more strongly tilted than those of the isomeric compound.
Introduction of the substituents at the 8-position increases the
strain in the molecule in comparison with the unsubstituted
[2.2]MPCP (1); the deformation of para-benzene ring of 8-
methyl[2.2]MPCP (2) was estimated to 15° by our previous
X-ray crystallography.9 Thus introduction of methyl group to
the para benzene ring of [2.2]MPCP also increases the strain in
the molecule. Therefore, there is substantial interest to prepare
the polymethyl substituted [2.2]MPCPs to investigate the
relationship between the strain and reactivity.10,11 Previously
we found that 8-methyl- and 8-hydroxy[2.2]MPCPs9 can be
conveniently prepared by AlCl3-MeNO2-catalysed trans-tert-
butylation of the corresponding tert-butyl derivatives. These
results suggest that 8,12,13,15,16-pentamethyl[2.2]MPCP
(3) might be also prepared from the corresponding tert-butyl
derivative, using the tert-butyl group as a positional protective
group on aromatic ring.ꢁꢇ±ꢁꢆ We report here the convenient
preparation of the title compounds and their treatment with
Lewis acid catalyst in a benzene solution.
Results and discussion
The preparative route of polymethyl substituted [2.2]MPCPs
8a and 8b is shown in Scheme 1. The preparation of 2,6-
5
6
7
4
3
9
2
8
Me
Me
Me
Me
Me
Me
16
15
10
1
14
11
12
13
3
2
1
Fig. 1
Me
Me
Me
ClCH2
R2
CH2Cl
R2
KOH/NaBH4
+
HSCH2
Me
CH2SH
Me
EtOH
high dilution
R1
6
4
a; R1= R2= Me
b; R1= tBu, R2= H
R1
R1
5
R2
R2
R2
R2
6
4
8
Me
Me
P(OEt)3
Me
Me
Me
S
Me
Me
S
Me
hu
16
15
13
12
Me
Me
a; R = R = Me
a; R = R = Me
7
8
(68%)
(54%)
(76%)
(71%)
2
2
b; R11= tBu, R2= H
b; R11= tBu, R2= H
Scheme 1
* Correspondent. E-mail: yamatot@cc.saga-u.ac.jp

JOURNAL OF CHEMICAL RESEARCH 2009 245
bis(chloromethyl)toluenes 4a and 4b has already been
described previously.12,17 1,4-Bis(sulfanylmethyl)-2,3,5,6-
tetramethylbenzene 6 was prepared from the corresponding
1,4-bis(chloromethyl)-2,3,5,6-tetramethylbenzene 5 according
the reported procedure.18 The cyclisation of bis(chloromethyl)
benzenes 4a and 4b and bis(sulfanylmethyl)benzene 6 was
carried out under highly diluted conditions in 10% ethanolic
KOH in the presence of a small amount of NaBH4, giving
the desired 2,11-dithia[3.3]MPCPs 7a and 7b in good yield.
Photolysis of 7a and 7b with a high-pressure murcury lamp
(400W) in triethylphosphate was carried out according to the
reported method19,20 to afford the corresponding [2.2]MPCPs
8a and 8b in good yields, respectively.
benzene at 50°C for 3 h the afforded metacyclophanes 9 and
10 in 65 and 30% yields along with the formation of tert-
butylbenzene 11. None of the expected product, 8,12,13,15,16-
pentamethyl[2.2]MPCP 3 was detected under the conditions
used. Prolonged reaction for 12 h under the same conditions
gave only 10 in 85% yield. This result suggests that 9 might
be an intermediate in the formation of 10. Indeed, 10 was also
obtained in good yield when 9 was treated with AlCl3±0H122
in benzene under the same reaction conditions (at 50°C for 12
h). Thus, the present Lewis acid isomerisation was supposed
to be much faster than trans-tert-butylation of 8b to afford
3. However, a similar catalytic treatment of 8a with AlCl3±
MeNO2 in benzene at 50°C for 12 h only afforded intractable
mixture of products.
The structures of the products 9 and 10 were determined
from their elemental analyses and spectral data. The 1H NMR
spectrum of 9 in CDCl3ꢀVKRZVꢀDQꢀXS¿HOGꢀVKLIWꢀRIꢀWKHꢀLQWHUQDOꢀ
methyl protons at G 0.48 and 0.54 ppm due to the ring current
effect23,24 of the opposite aromatic ring compared to those of
original [2.2]MPCP 8aꢉꢀ7KHꢀVLPLODUꢀ¿QGLQJVꢀZHUHꢀREVHUYHGꢀ
in 10. These data strongly support the [2.2]metacyclophane
structures 9 and 10.
The structures of 8a and 8b were determined on the basis
1
of their elemental analyses and spectral data. The H NMR
spectrum of 8b in CDCl3 shows a singlet at G 1.74 ppm for
methyl protons at 15,16-positions which is in a strongly
shielding region of opposite meta-bridged benzene ring and
G 2.31 ppm for external methyl protons at 12,13-positions,
respectively. On the other hand, the signals of the internal
methyl protons at 8-position and two aromatic protons for
&ꢈꢅꢀDQGꢀ&ꢈꢆꢀZHUHꢀREVHUYHGꢀDWꢀXSSHUꢀ¿HOGꢀRIꢀG 1.75 and 6.63
ppm which is in a strongly shielding region of opposite para-
bridged benzene ring.
X-ray crystallographic study of 8a shows that the
compound is apparently conformationally more rigid than
(1, R=H) because its methyl substituent at 8 position is likely
impinge upon the electron cloud of the para-bridged one. It
is quite interesting that the increase of degree of deformation
of para-benzene ring, which was estimated to 18.84° of 8a
compared with that of 2 to 15°. Introduction of the methyl
groups at 12,13,15 and 16 positions increases the deformation
of para-benzene ring. Thus introduction of methyl groups
to the para benzene ring of [2.2]MPCP also increases the
strain in the molecule in comparison with the unsubstituted
8-methyl[2.2]MPCP 2.9 It was also found the distortion angle
of meta benzene ring from planality is 15.94° in comparison
with that of 8,16-dimethyl[2.2]metacyclophane (17.18°).21,22
Attempted TiCl4-catalysed trans-tert-butylation of 8b in
benzene carried out under various of conditions failed. Only the
recovery of the starting compound 8b resulted. Interestingly,
the AlCl3±0H122-catalysed trans-tert-butylation of 8b in
Fig.
2
X-ray (ellipsoids) structure of 4,5,6,8,12,13,15,16-
octamethyl[2.2]MPCP 8a. The thermal ellipsoids are given at
50% probability.
tBu
tBu
tBu
Me
+H+
AlCl3/MeNO2
Me
Me
+
Me
Me
Me
Me
Me
Me
+
8b
8b
Me
+
H
Me
Me
Me
Me
Me
Me
benzene
50°C for 3 h
H
Me
Me
Me
3
Me
9
B
A
tBu
tBu
-H+
Me
Me
Me
Me
+
+
9
10
+
11
Me
Me
Me
Me
H
Me
Me
10
C
Scheme 2
Scheme 3

246 JOURNAL OF CHEMICAL RESEARCH 2009
Preparation of 5,6,7,9,14,15,17,18-octamethyl-2,11-dithia[3.3]
metaparacyclophane (7a): A solution of 4a (5.27 g, 20 mmol) and 6
(4.52 g, 20 mmol) in benzene (100 mL) was added dropwise over a
period of 12 h from a Hershberg funnel with stirring under nitrogen
to a solution of potassium hydroxide (4.0 g, 71 mmol) and sodium
borohydride (1 g) in ethanol (4 l). After the addition, the reaction
mixture was concentrated and the residue was extracted with CH2Cl2
(200 mL u 2). The CH2Cl2 extract was concentrated and the residue
was chromatographed on silica gel (Wako C-300, 400 g) (hexane-
benzene, 1:1 v/v, as eluent) to give a colourless solid. Recrystallisation
from hexane-benzene 1:1 (v/v) gave 5,6,7,9,14,15,17,18-octamethyl-
2,11-dithia[3.3]metaparacyclophane (7a) as colourless prisms (5.22
JꢃꢀꢆꢏꢊꢋꢃꢀPꢉSꢉꢀꢇꢌꢂ±ꢇꢌꢏ°C; GH (CDCl3) 1.74 (3H, s, CH3), 1.79 (6H,
s, CH3), 2.12 (3H, s, CH3), 2.27 (6H, s, CH3), 2.36 (6H, s, CH3), 3.62
(2H, d, J = 16.2 Hz, CH2), 3.67 (2H, d, J = 13.7 Hz, CH2), 3.70 (2H,
d, J = 16.2 Hz, CH2) and 4.34 (2H, d, J = 13.5 Hz, CH2); GC (CDCl3)
16.05, 16.21, 16.73, 17.88, 18.44, 30.12, 30.66, 129.43, 131.72,
132.69, 133.28, 133.39, 133.44 and 133.60; m/z 384 (M+) (Found: C,
75.05; H, 8.45. C24H32S2 (384.64) required C, 74.94; H, 8.39).
Cyclisation reactions of 4b and 6 were carried out using the same
procedure as described above to afford 7b.
A mechanism for the formation of the isomerisation
products 9 and 10 from 8b is tentatively proposed in Scheme 3.
Cram et al. reported25 the AlCl3-catalysed isomerisation
of [2.2]paracyclophane to the less strained [2.2]MPCP 1
along with transannular isomerisation products, 1,2,2a,3,4,5-
hexahydropyrene and [2.2]metacyclophane. In the case of
5-tert-butyl-8,12,13,15,16-pentamethyl[2.2]MPCP 8b, the
protonation of the ipso-position of ethylene bridge on the para-
benzene ring could afford the cation intermediate (A), which
could isomerise to the strainless 5-tert-butyl-8,12,13,14,16-
pentamethyl[2.2]metacyclophane 9 via cation intermediates B
and C. This novel isomerisation reaction might attributed to
the methyl group at the 8-position of meta benzene ring and the
methyl groups at the 12,13,15,16-positions of para benzene
ring, which increase the strain in the molecule in comparison
with the unsubstituted [2.2]MPCP 1 and 8-methyl[2.2]MPCP
2. We previously reported the AlCl3±0H122 catalysed
trans-tert-butylation of 5-tert-butyl-8-methyl[2.2]MPCP
afforded only the desired 8-methyl[2.2]MPCP 2.9 No present
isomerisation reaction was observed under the conditions
used. These results are attributable to the increase of degree
of deformation of para-benzene ring, which was estimated to
18.84° by the X-ray crystallographic study of 8a compared
with that of 1 to 13° and 2 to 15°. Finally, the trans-tert-
butylation of compound 9 would give 8,12,13,14,16-pentamet
hyl[2.2]metacyclophane 10.
6-tert-Butyl-9,14,15,17,18-pentamethyl-2,11-dithia[3.3]metapara-
cyclophane (7bꢋꢐꢀ&RORXUOHVVꢀSULVPVꢀꢍꢅꢉꢎꢑꢀJꢃꢀꢎꢅꢊꢋꢃꢀPꢉSꢉꢁꢅꢂ±ꢁꢅꢏ°C;
GH (CDCl3) 1.32 (9H, s, tBu), 1.79 (3H, s, CH3), 1.89 (6H, s, CH3),
2.34 (6H, s, CH3), 3.50 (2H, d, J = 15.2 Hz, CH2), 3.61 (2H, d,
J = 14.2 Hz, CH2), 3.62 (2H, d, J = 15.2 Hz, CH2), 4.25 (2H, d,
J = 14.2 Hz, CH2) and 7.10 (2H, s, ArH); GC (CDCl3) 14.79. 16.44,
17.90. 30.76, 31.59. 32.24, 34.27, 124.90, 128.66, 131.91, 132.33,
133.80, 136.99 and 145.51; m/z 398 (M+) (Found: C, 75.46; H, 8.42.
C25H34S2 (398.67) required C, 75.32; H, 8.6).
3KRWRO\VLVꢀ RIꢀ GLVXO¿GH 7a to give 4,5,6,8,12,13,14,16-octamethyl
[2.2]metaparacyclophane (8a): A solution of 7a (480 mg, 1.25 mmol)
in triethylphosphate (100 mL) was irradiated with a 100 W high
pressure mercury lamp (Riko Kagaku Sangyo Co.) for 6 h at
URRPꢀ WHPSHUDWXUHꢀ LQꢀ DUJRQꢀ DWRPRVSKHUHꢉꢀ$ꢀ 3\UH[ꢀ ¿OWHUꢀ ZDVꢀ XVHGꢉꢀ
$IWHUꢀWKHꢀUHDFWLRQꢀPL[WXUHꢀZDVꢀSRXUHGꢀWRꢀLFH±ꢁꢌꢊꢀ1D2+ꢀVROXWLRQꢀ
(200 mL), it was stirred at room temperature for 3 h and and extracted
with CH2Cl2 (200 mL u 2). The CH2Cl2 extract was washed with
water (100 mL), brine (100 mL) and dried (Na2SO4) and evaporated
in vacuo to leave the residue. The residue was chromatographed on
silica gel (Wako C-300, 400 g) (hexane as eluent) to give a colourless
solid. Recrystallisation from hexane gave 4,5,6,8,12,13,14,16-octa-
methyl[2.2]metaparacyclophane (8a) as colourless prisms (304 mg,
ꢂꢆꢊꢋꢃꢀPꢉSꢉꢁꢏꢂ±ꢁꢏꢑ°C; GH (CDCl3) 1.61 (6H, s, CH3), 1.72 (3H, s,
CH3), 2.07 (3H, s, CH3), 2.19 (6H, s, CH3), 2.31 (6H, s, CH3) and
ꢇꢉꢆꢌ±ꢄꢉꢁꢏꢀ ꢍꢏ+ꢃꢀ Pꢃꢀ CH2); GC (CDCl3) 15.83, 15.98. 16.07, 16.26,
18.82, 26.85, 28.32, 129.38, 130.0, 130.5, 131.7, 133.9, 135.1 and
136.2; m/z 320 (M+) (Found: C, 90.13; H, 10.19. C24H32 (320.52)
required C, 89.94; H, 10.06).
Conclusions
It is concluded that the above isomerisation reaction of 8-
methyl[2.2]MPCP to form 8-methyl[2.2]metacyclophane is
strongly affected by the bulkiness of the methyl group in the
8-position of meta benzene ring and the methyl groups at the
12,13,15,16-positions of para benzene ring which increase the
strain in the molecule. Further studies on the chemical properties
of polymethyl substituted [2.2]MPCPs are now in progress.
Experimental
All melting points are uncorrected. 1H NMR spectra were recorded
at 300 MHz on a Nippon Denshi JEOL FT-300 NMR spectrometer
in deuteriochloroform with Me4Si as an internal reference. IR spectra
were measured as KBr pellets on a Nippon Denshi JIR-AQ2OM
spectrometer. Mass spectra were obtained on a Nippon Denshi JMS-
HX110A Ultrahigh Performance Mass Spectrometer at 75 eV using
a direct-inlet system. Elemental analyses were performed by Yanaco
MT-5.
Photolysis of 7b was carried out using the same procedure as
described above to afford 8b in 71% yield.
Materials: 2,6-Bis(chloromethyl)-4-tert-butyltoluene 4b12 and
1,4-bis(chloromethyl)-2,3,5,6-tetramethylbenzene 517 were prepared
according to the literature.
5-tert-Butyl-8,12,13,15,16-pentamethyl[2.2]metaparacyclophane
(8bꢋꢐꢀ &RORXUOHVVꢀ SULVPVꢃꢀ PꢉSꢉꢁꢂꢆ±ꢁꢂꢏꢀƒ&ꢒꢀ GH (CDCl3) 1.29 (9H, s,
tBu), 1.74 (6H, s, CH3), 1.75 (3H, s, CH3), 2.31 (6H, s, CH3ꢋꢃꢀꢇꢉꢅꢑ±
2.60 (2H, m, CH2ꢋꢃꢀꢇꢉꢂꢏ±ꢇꢉꢑꢂꢀꢍꢅ+ꢃꢀPꢃꢀCH2ꢋꢃꢀꢄꢉꢁꢌ±ꢄꢉꢇꢌꢀꢍꢇ+ꢃꢀPꢃꢀCH2)
and 6.63 (2H, s, ArH); GC (CDCl3) 16.57, 16.89, 17.33, 29.67, 29.90,
32.20, 34.45, 123.41, 131.38, 132.35, 133.23, 135.76, 138.72, and
144.55; m/z 334 (M+) (Found: C, 89.73; H, 10.17. C25H34 (334.55)
required C, 89.76; H,10.24).
AlCl3-MeNO2 Catalysed trans-tert-butylation of 8b in benzene:
To a solution of 8b (230 mg, 0.68 mmol) in benzene (30 mL)
was added a solution of AlCl3 (27.2 mg, 0.204 mmol) in MeNO2
(0.05 ml). After the reaction mixture had been stirred for 3 h at 50°C,
it was poured into ice-water and extracted with ether (30 mL u 2).
The ether extract was dried (Na2SO4) and concentrated under reduced
pressure to leave the residue. The residue was chromatographed on
silica gel (Wako C-300, 200 g) (hexane as eluent) to give 9 (148 mg,
65%) and 10 (57 mg, 30%) as a colourless solid, respectively.
The formation of tert-butylbenzene (11ꢋꢀZDVꢀFRQ¿UPHGꢀE\ꢀ*/&ꢉ
5-tert-Butyl-8,12,13,15,16-pentamethyl[2.2]metacyclophane (9):
&RORXUOHVVꢀSULVPVꢀꢍKH[DQHꢋꢃꢀPꢉSꢉꢁꢅꢇ±ꢁꢅꢅꢀƒ&ꢒꢀGH (CDCl3) 0.48 (3H,
s, CH3), 0.54 (3H, s, CH3), 1.29 (9H, s, tBu), 2.15 (3H, s, CH3), 2.31
(6H, s, CH3ꢋꢃꢀ ꢇꢉꢅꢆ±ꢇꢉꢎꢏꢀ ꢍꢇ+ꢃꢀ Pꢃꢀ CH2ꢋꢃꢀ ꢇꢉꢆꢎ±ꢇꢉꢂꢂꢀ ꢍꢇ+ꢃꢀ Pꢃꢀ CH2),
ꢇꢉꢏꢌ±ꢇꢉꢏꢏꢀꢍꢇ+ꢃꢀPꢃꢀCH2ꢋꢃꢀꢄꢉꢇꢁ±ꢄꢉꢄꢌꢀꢍꢇ+ꢃꢀPꢃꢀCH2) and 7.12 (2H, s,
ArH); GC (CDCl3) 14.07, 15.42, 14.44, 31.41, 32.51, 33.93, 34.91,
123.88, 129.70, 131.77, 132.63, 136.89, 139.15, 139.26 and 146.88;
m/z 334 (M+) (Found: C, 89.68; H, 10.15. C25H34 (334.55) required
C, 89.76; H,10.24).
Preparation of 2,6-bis(chloromethyl)-1,3,4,5-tetramethylbenzene
(4a): To a solution of 1,2,3,5-tetramethylbenzene (67.1 g, 0.5 mol)
and chloromethyl methyl ether (150 mL) was added zinc chloride
(40 g, 0.29 mol) at room temperature. After the reaction mixture
was stirred for 10 min, it was poured into ice-water (300 mL) and
extracted with CH2Cl2 (200 mL u 3). The CH2Cl2 extract was washed
with saturated aqueous NaCl (100 mL u 2), water (200 mL) and
dried (Na2SO4) and evaporated in vacuo to leave a colourless solid.
Recrystallisation from hexane gave 4a as colourless prisms (88.0 g,
ꢂꢆꢉꢁꢊꢋꢃꢀPꢉSꢉꢀꢁꢁꢌ±ꢁꢁꢁ°C (lit.17 114 °C).
Preparation of 1,4-bis(sulfanylmethyl)-2,3,5,6-tetramethylbenzene
(6): A solution of 1,4-bis(chloromethyl)-2,3,5,6-tetramethylbenzene 5
(9.25 g, 0.40 mmol) and thiourea (6.7 g, 88 mmol) in DMSO (50 mL)
was stirred at room temperature under atmosphere of nitrogen for
14 h. After the reaction mixture was poured into a solution of NaOH
ꢍꢇꢌꢀJꢋꢀLQꢀZDWHUꢀꢍꢇꢌꢌꢀP/ꢋꢃꢀWKHꢀVROXWLRQꢀZDVꢀVWLUUHGꢀIRUꢀꢁꢀKꢃꢀDFLGL¿HGꢀ
with aqueous 10% HCl and extracted with CH2Cl2 (100 mL u 2).
The CH2Cl2 extract was washed with water (100 mL) and saturated
aqueous NaCl (100 mL), and dried (Na2SO4) and evaporated in
vacuo to leave a colourless solid. Recrystallisation from hexane gave
6ꢀDVꢀFRORXUOHVVꢀSULVPVꢀꢍꢆꢉꢎꢀJꢃꢀꢂꢁꢉꢏꢊꢋꢃꢀPꢉSꢉꢀꢁꢁꢄ±ꢁꢁꢅ°C; Qmax/cm-1
(KBr) 3040, 2960, 2900, 2550, 1430, 1370, 1225, 1010, 790 and 675;
GH (CDCl3) 1.56 (2H, t, J = 6.6 Hz, SH), 2.28 (12H, s, CH3) and 3.80
(4H, d, J = 6.6 Hz, CH2); m/z 226 (M+) (Found: C, 63.61; H, 8.13.
C12H18S2 (226.4) requires C, 63.66; H, 8.01%).

JOURNAL OF CHEMICAL RESEARCH 2009 247
8,12,13,15,16-Pentamethyl[2.2]metacyclophane (10): Colourless
SULVPVꢀ ꢍKH[DQHꢋꢃꢀ PꢉSꢉꢁꢅꢎ±ꢁꢅꢂ°C; GH (CDCl3) 0.48 (3H, s, CH3),
0.49 (3H, s, CH3), 2.16 (3H, s, CH3), 2.32 (6H, s, CH3), 2.50 (2H,
ddd, J = 4.5, 12.0, 13.1 Hz, CH2), 2.70 (2H, ddd, J = 3.9, 12.0, 12.2
Hz, CH2), 2.84 (2H, ddd, J = 3.0, 4.5, 12.5 Hz, CH2), 3.26 (2H, ddd,
J = 3.0, 3.9, 13.1 Hz, CH2), 6.87 (1H, t, J = 7.3 Hz, ArH) and 7.01
(2H, d, J = 7.3 Hz, ArH); GC (CDCl3) 14.07, 15.42, 14.44, 31.41,
32.51, 33.93, 34.91, 123.88, 129.70, 131.77, 132.63, 136.89, 139.15,
139.26 and 146.88; m/z 278 (M+) (Found: C, 90.75; H, 9.56. C21H26
(278.44) required C, 90.59; H, 9.41).
Received 4 December 2008; accepted 2 February 2009
Paper 08/0316 doi: 10.3184/030823409X430185
Published online: 29 April 2009
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UHÀHFWLRQVꢀ PHDVXUHGꢀ RQꢀ Dꢀ 5LJDNXꢀ 6DWXUQꢀ &&'ꢀ GLIIUDFWRPHWHUꢃꢀ RIꢀ
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