482 JOURNAL OF CHEMICAL RESEARCH 2008
TiCl4 (3.0 cm3, 27.3 mmol) in CH2Cl2 (10 cm3) at 0ꢀ°C. After the
reaction mixture was stirred at room temp. for 1 h, it was poured
into a large amount of ice/water (50 cm3) and extracted with CH2Cl2
(2ꢀuꢀ20 cm3). The combined extracts were washed with water, dried
with Na2SO4 and concentrated. The residue was chromatographed
over silica gel (Wako C–300, 200 g) with benzene as eluent to
give 3a (914 mg, 65%) as a colourless solid. Recrystallisation
from hexane gave 1,3-bis(5-formyl-2-methoxyphenyl)propane 3a
as colourless prisms, m.p. 82–84ꢀ°C; Qmax (KBr)/cm-1ꢃꢆꢎꢐꢋꢃꢀ& 2ꢄꢏꢃ
GH(CDCl3) 1.90–1.96 (m, 2 H, ArCH2CH2CH2Ar), 2.71 (4H, t,
Jꢃ ꢃ ꢐꢂꢇꢃ +]ꢌꢃ$UCH2CH2CH2Ar), 3.91 (6 H, s, OMe), 6.91 (2H, d,
Jꢃ ꢃꢐꢂꢇꢃ+]ꢌꢃ$UH), 7.70 (2H, d, Jꢃ ꢃꢁꢂꢈꢃ+]ꢌꢃ$UH), 7.72 (2H, dd, Jꢃ ꢃꢁꢂꢈꢌꢃ
7.8 Hz), 9.86 (2H, s, CHO); m/z: 312 (M + ) (Found C, 72.85; H, 6.55.
C19H20O4 (312.37) requires C, 73.06; H, 6.45%).
3b: Prepared as described for 3a in 95% yield. 1,4-Bis(5-formyl-
2-methoxyphenyl)butane (3b) was obtained as colourless prisms
(petroleum ether); m.p. 95–97ꢀ°C; Qmax (KBr)/cm-1ꢃ ꢆꢎꢐꢋꢃ ꢀ& 2ꢄꢏꢃ
GH(CDCl3) 1.61–1.18 (4H, m, ArCH2CH2CH2CH2Ar), 2.69 (4H, t,
Jꢃ ꢃ ꢇꢂꢐꢃ +]ꢌꢃ$UCH2CH2CH2Ar), 3.96 (6 H, s, OMe), 6.94 (2H, d,
Jꢃ ꢃ ꢇꢂꢉꢃ +]ꢌꢃ$UH), 7.67 (2H, d, Jꢃ ꢃ ꢁꢂꢁꢃ +]ꢌꢃ$UH), 7.70 (2 H, dd,
Jꢃ ꢃꢁꢂꢈꢌꢃꢇꢂꢉꢃ+]ꢌꢃ$UH), 9.85 (2H, s, CHO); m/z: 326 (M + ) (Found C,
73.53; H, 6.89. C20H22O4 (326.4) requires C, 73.59; H, 6.79%).
group. In contrast, in the case of 7b, the aromatic proton (HA)
was observed at G 7.51 (a doublet, Jꢃ ꢃꢁꢂꢍꢃ+]ꢄꢂꢃ7KLVꢃREVHUYDWLRQꢃ
strongly suggests that 7b adopts syn-conformation. This
¿QGLQJꢃLQGLFDWHVꢃWKHꢃGLIIHUHQWꢃFRQIRUPDWLRQꢃLVꢃSRVVLEOHꢃLQꢃWKHꢃ
[2.4]MCP-1,2-dione 7b as the length of the one methylene
bridge increases from the [2.3]MCP-1,2-dione 7a. We also
observed one of the aromatic protons (HB) to be deshielded
by the carbonyl group on the ethylene bridge resulting in a
GRZQ¿HOGꢃVKLIWꢃꢀG 8.18 ppm).
7KHꢃ KLJKHUꢃ IUHTXHQF\ꢃ RIꢃ & 2ꢃ VWUHWFKLQJꢃ YLEUDWLRQꢃ LQꢃ
the IR spectrum for [2.4]MCP-1,2-dione 7a (1685 cm-1)
in comparison with that for the reference compound benzil
10 (1662 cm-1ꢄꢃ SUHVXPDEO\ꢃ UHÀHFWVꢃ WKHꢃ GHYLDWLRQꢃ RIꢃ WKHꢃ
carbonyl group from the plane of the benzene ring rather
than conjugation between the carbonyl group and the
EHQ]HQHꢃULQJꢂꢃ7KLVꢃ¿QGLQJꢃLVꢃVLPLODUꢃWRꢃWKRVHꢃIRUꢃWKHꢃVWUDLQHGꢃ
[2.2]paracyclophan-1-ones12,40,41 for which absorptions are
toward wavelengths characteristic of unconjugated ketones
due to the expanded O–C–C bond angles. Similar higher
frequency was observed in the higher [2.4]MCP-1,2-dione 7b
(1667 cm-1ꢄꢌꢃEXWꢃE\ꢃLQFUHDVLQJꢃRQHꢃPHWK\OHQHꢃEULGJHꢌꢃWKHꢃ& 2ꢃ
stretching vibration becomes to appear at the normal positions
in [2.4]MCP-1,2-dione 7b.
McMurry coupling reaction of 3
The McMurry reagent was prepared from TiCl4 [23.8 g (13.8 cm3),
125 mmol] and Zn powder (18 g, 275 mmol) in dry THF
(500 cm3) under nitrogen. A solution of 1,3-bis(5-formyl-2-
methoxyphenyl)propane 3a (2.81 g, 9.0 mmol) and pyridine
(22.8 cm3, 200 mmol) in dry THF (250 cm3) was added within
60 h to the black mixture of the McMurry reagent by using a high-
GLOXWLRQꢃ WHFKQLTXHꢃ ZLWKꢃ FRQWLQXRXVꢃ UHÀX[LQJꢃ DQGꢃ VWLUULQJꢂꢃ 7KHꢃ
UHDFWLRQꢃ PL[WXUHꢃ ZDVꢃ UHÀX[HGꢃ IRUꢃ DGGLWLRQDOꢃ ꢇꢃ Kꢌꢃ FRROHGꢃ WRꢃ URRPꢃ
temperature, and treated with aqueous 10% K2CO3 (200 cm3) at
0ꢀ°C. The reaction mixture was extracted with CH2Cl2 (3ꢀuꢀ200 cm3).
The combined extracts were washed with water, dried with Na2SO4
and concentrated. The residue was chromatographed over silica gel
(Wako C-300, 300 g) with hexane–benzene (2:1) and CHCl3–EtOAc
(1:1) as eluents to give 4a (590 mg, 23%) and 5a (1.84 g, 65%) as a
colourless solid, respectively.
Conclusion
In conclusion, we have developed a convenient preparation of
a series of syn- and anti-[2.n]MCP-1-enes 4 and [2.n]MCP-
1,2-diols 5 by a McMurry cyclisation of 1,n-bis(5-formyl-2-
methoxyphenyl)alkanes 3. Also, [2.n]MCP-1,2-diols 5 were
converted to the 1,2-diones 7 by Albright–Goldman oxidation.
Further studies on the chemical properties of the diketones 7
are now in progress.
Experimental
6,13-Dimethoxy[2.3]metacyclophan-1-ene 4a: Colourless prisms
(from methanol), m.p. 133–135ꢀ°C; Qmax (KBr)/cm-1 2936, 2898,
2833, 1601, 1496, 1438, 1288, 1248, 1187, 1127, 1032, 948, 815,
783; GH(CDCl3, 27ꢀ°C) 1.93–1.98 (2H, m, ArCH2CH2CH2Ar), 2.35
(4H, broad s, ArCH2CH2CH2Ar), 3.82 (6H, s, OMe), 5.95 (2H, d,
Jꢃ ꢃ ꢁꢂꢍꢃ +]ꢌꢃ $UH), 6.58 (2H, s, CH), 6.68 (2H, d, Jꢃ ꢃ ꢇꢂꢁꢃ +]ꢌꢃ
ArH), 6.93 (2H, dd, Jꢃ ꢃ ꢁꢂꢍꢌꢃ ꢇꢂꢁꢃ +]ꢌꢃ $UH); GH(CDCl3/CS2, 1:3,
–40ꢀ°C) 0.82–0.92 (1H, m, ArCH2CH2CH2Ar), 1.71–0.84 (1H, m,
ArCH2CH2CH2Ar), 1.93–2.03 (2H, m, ArCH2CH2CH2Ar), 2.90–3.02
(2H, m,ArCH2CH2CH2Ar), 3.82 (6H, s, OMe), 5.95 (2H, d, Jꢃ ꢃꢁꢂꢍꢃ+]ꢌꢃ
ArH), 6.58 (2H, s, CH), 6.68 (2H, d, Jꢃ ꢃꢇꢂꢁꢃ+]ꢌꢃ$UH), 6.93 (2H,
dd, Jꢃ ꢃꢁꢂꢍꢌꢃꢇꢂꢁꢃ+]ꢌꢃ$UH); m/z: 280 (M + ) (Found C, 81.32; H, 7.31.
C19H20O2 (280.37) requires C, 81.40; H, 7.19%).
1H NMR spectra were recorded at 300 MHz on a Nippon Denshi
JEOL FT-300 NMR spectrometer in deuteriochloroform with Me4Si
as an internal reference. IR spectra were measured as KBr pellets
on a Nippon Denshi JIR-AQ2OM spectrometer. Mass spectra were
obtained on a Nippon Denshi JMS-HX110A Ultrahigh Performance
Mass Spectrometer at 75 eV using a direct-inlet system. Elemental
analyses were performed by Yanaco MT-5.
Materials
Preparations of 1,n-bis(5-tert-butyl-2-methoxyphenyl)alkanes 1 was
previously described.30,31
1-endo-2-endo-dihydroxy-6,13-dimethoxy[2.3]metacyclophane
5a: Colourless prisms (from petroleum ether), m.p. 218–219ꢀ°C; Qmax
(KBr)/cm-1 3563, 3327 (OH), 2941, 1608, 1502, 1244, 1128, 1027,
825, 615; GH(CDCl3) 1.80–1.95 (2H, broad s, ArCH2CH2CH2Ar),
1.98–2.12 (2H, m, ArCH2CH2CH2Ar), 2.75 (2H, s, OH), 2.94–3.05
(2H, m, ArCH2CH2CH2Ar), 3.82 (6H, s, OMe), 4.34 (2H, s, CH),
4.99 (2H, d, J = 2.4 Hz, ArH), 6.80 (2H, d, Jꢃ ꢃꢐꢂꢇꢃ+]ꢌꢃ$UH), 7.39
(2H, dd, Jꢃ ꢃꢁꢂꢍꢌꢃꢐꢂꢇꢃ+]ꢌꢃ$UH); m/z: 314 (M + ) (Found C, 72.53; H,
7.06. C19H22O4 (314.38) requires C, 72.59; H, 7.05%).
Trans-tert-butylation of 1a to give
2a: To a solution of 1a (2.21 g, 6.0 mmol) in benzene (16 cm3) was
added a solution of anhydrous aluminum chloride (1.60 g, 12.0 mmol)
in nitromethane (3.2 cm3). After the reaction mixture was stirred for
12 h at 50ꢀ°C, the reaction was quenched by the addition of 10%
hydrochloric acid, and the solution was washed with water, dried
over Na2SO4, and concentrated. The residue was chromatographed
over silica gel (Wako C-300, 300 g) with hexane–benzene (1:1) as
eluent to give crude 2a as a colourless solid. Recrystallisation from
petroleum ether gave 1,3-bis(2-methoxyphenyl)propane (2a) (1.0 g,
65%) as a colourless prisms, m.p. 63–65ꢀ°C; Qmax(KBr)/cm-1: 3000,
2939, 2856, 1601, 1588, 1494, 1466, 1434, 1325, 1291, 1242,
1174, 1158, 1049, 1026, 927, 828, 756; GH (CDCl3) 1.83–1.95 (2H,
m, ArCH2CH2CH2Ar), 2.67 (4H, t, Jꢃ ꢃꢐꢂꢆꢃ+]ꢌꢃ$UCH2CH2CH2Ar),
3.77 (6 H, s, OMe), 6.79–6.88 (4H, m, ArH), 7.12–7.17 (4H, m,
ArH); m/z: 256 (M+) (Found: C, 79.45; H, 7.58. C17H20O2 (256.34)
requires C, 79.65; H, 7.86%).
Similarly, compounds 4b and 5b were prepared in the same manner
as described above in 36 and 53% yields, respectively.
6,14-Dimethoxy[2.4]metacyclophan-1-ene 4b: Colourless prisms
(from methanol), m.p. 117–119ꢀ°C; Qmax (KBr)/cm-1 2954, 2912, 2835,
1500, 1263, 1245, 1116, 1029, 824; GH(CDCl3) 1.18–1.32 (2H, m,
ArCH2CH2CH2CH2Ar), 1.52–1.68 (2H, m, ArCH2CH2CH2CH2Ar),
2.23–2.38 (2H, broad s, ArCH2CH2CH2CH2Ar), 2.75–2.93 (2H,
broad s, ArCH2CH2CH2CH2Ar), 3.81 (6H, s, OMe), 6.39 (2H, s, CH),
6.77 (2H, d, Jꢃ ꢃꢇꢂꢉꢃ+]ꢌꢃ$UH), 6.98 (2H, dd, Jꢃ ꢃꢁꢂꢍꢌꢃꢇꢂꢁꢃ+]ꢌꢃ$UH),
7.55 (2H, d, Jꢃ ꢃꢁꢂꢍꢌꢃ$UH); m/z: 294 (M + ) (Found C, 81.69; H, 7.53.
C20H22O2 (294.39) requires C, 81.60; H, 7.53%).
2b: Prepared as described for 2a in 92% yield. 1,4-Bis(2-methoxy-
phenyl)butane (2b) was obtained as colourless prisms (petroleum
ether); m.p. 74–76ꢀ°C; Qmax(KBr)/cm-1: 3000, 2939, 2856, 1601,
1588, 1494, 1466, 1434, 1325, 1291, 1242, 1174, 1158, 1049, 1026,
927, 828, 756; GH (CDCl3) 1.61–1.67 (4H, m, ArCH2CH2CH2CH2Ar),
2.64 (4H, t, Jꢃ ꢃꢐꢂꢆꢃ+]ꢌꢃ$UCH2CH2CH2Ar), 3.80 (6 H, s, Me), 6.81–
6.89 (4H, m, ArH), 7.11–7.18 (4H, m, ArH); m/z: 270 (M+) (Found:
C, 80.23; H, 8.33. C18H22O2 (270.37) requires C, 79.96; H, 8.20%).
3a: To a solution of 2a (1.15 g, 4.5 mmol) and Cl2CHOCH3
(1.14 cm3, 12.6 mmol) in CH2Cl2 (10 cm3) was added a solution of
1-endo-2-endo-Dihydroxy-6,14-dimethoxy[2.4]metacyclophane
5b: Colourless needles (from CH2Cl2), m.p. 218–219ꢀ°C; Qmax (KBr)/
cm-1 3558 3386 (OH), 2931, 2863, 1250, 1182, 1111, 1079, 1056;
GH(CDCl3) 0.75–1.68 (2H, broad s, ArCH2CH2CH2CH2Ar), 1.41–
1.65 (2H, broad s, ArCH2CH2CH2CH2Ar), 2.09–2.38 (2H, broad s,
ArCH2CH2CH2CH2Ar), 2.85 (2H, s, OH), 2.72–3.10 (2H, broad s,