Chemistry Letters Vol.34, No.12 (2005)
1661
t
t
O
O
Bu Bu
t
t
O
O
Bu Bu
t
t
Bu
Bu
t
t
Bu
Bu
2-
3
10
Chart 2.
flects their rigid structures. The relatively high third reduction
potential of 3, which corresponds to the formation of trianion
radical, indicates that the electron affinity of dianion 32ꢂ is
enhanced by antiaromatic character of the formed pyracylene
moiety. Further studies on 3 toward the development of photo-
responsive molecular switch, like 10, are in progress (Chart 2).
Figure 1. ORTEP drawings (50% thermal ellipsoids) of 3; a)
front view, b) side view. Hydrogen atoms are omitted for clarity.
ꢁ
ꢀ
Selected bond lengths [A] and angles [ ]: O1–C1 1.232(4), C1–
C2 1.484(5), C2–C3 1.354(5), C3–C4 1.442(5), C4–C13
1.378(5), C13–C14 1.487(5), C13–C24 1.509(5), C14–C15
1.388(5), C15–C16 1.425(5), C16–C17 1.385(5), C17–C18
1.483(6), C18–C19 1.355(6), C25–C26 1.361(5), C4–C13–C14
124.6(4), C4–C13–C24 126.7(4), C14–C13–C24 107.2(4),
C13–C14–C25 104.4(4), C16–C17–C18 139.5(5), and C17–
C18–C19 108.6(4).
This work was supported by a Grant-in-Aid for Scientific
Research (No. 16550036) from the Ministry of Education,
Culture, Sports, Science and Technology.
References and Notes
1
2
3
B. M. Trost, M. Bright, C. Frihart, and D. Brittelli, J. Am. Chem.
Soc., 93, 737 (1971).
B. Freiermuth, S. Gerber, A. Riesen, J. Wirz, and M. Zehnder,
J. Am. Chem. Soc., 112, 738 (1990).
For example: W. D. Neudorff, D. Lentz, M. Anibarro, and A. D.
5
4
Schluter, Chem.—Eur. J., 9, 2745 (2003).
¨
4
5
6
7
8
B. M. Trost, J. Am. Chem. Soc., 91, 918 (1969).
S. Oishi, T. Urabe, and R. Kotake, Chem. Lett., 2002, 808.
A. Gourdon, Eur. J. Org. Chem., 1998, 2797.
H. Kurata, T. Tanaka, and M. Oda, Chem. Lett., 1999, 749.
H. Kurata, Y. Takehara, T. Kawase, and M. Oda, Chem. Lett., 32,
538 (2003).
log
ε
3
9
T. Kawase, Y. Minami, N. Nishigaki, S. Okano, H. Kurata, and
M. Oda, Angew. Chem., Int. Ed., 44, 316 (2005).
200
300
400
500
600
700
wavelength / nm
10 H. Kurata, T. Tanaka, T. Sauchi, T. Kawase, and M. Oda, Chem.
Lett., 1997, 947.
Figure 2. UV–vis spectra of 3 (solid line) and 4 (dashed line) in
cyclohexane.
11 Selected physical and spectroscopic data 3þand 4: 3: brown crystals;
mp >300 ꢁC; MS (EI) m=z 586 (½M þ 4ꢃ , 89%), 584 (½M þ 2ꢃþ,
100), 582 (Mþ, 77), 293 (½M þ 4ꢃ2þ, 17); 1H NMR (270 MHz,
CD2Cl2) ꢁ 8.10 (d, J ¼ 2:5 Hz, 2H), 7.84 (d, J ¼ 7:3 Hz, 2H),
7.69 (d, J ¼ 7:3 Hz, 2H), 7.26 (d, J ¼ 2:5 Hz, 2H), 7.03 (s, 2H),
1.44 (s, 18H), 1.20 (s, 18H); 13C NMR (67.8 MHz, CD2Cl2) ꢁ
186.73, 149.91, 149.81, 147.61, 139.85, 137.86, 135.35, 133.54,
131.76, 131.54, 128.86, 127.48, 127.17, 124.17, 36.30, 35.78,
29.90, 29.59; IR (KBr) ꢂ 1597 cmꢂ1 (CO); UV–vis (cyclohexane)
ꢃmax 503sh (log " ¼ 4:00), 418 (4.47), 289 (3.89), 270 (3.91), 233
(3.97) nm. 4: þdeep purple crystals; 276.0–277.0 ꢁC; MS (EI) m=z
586 (½M þ 2ꢃ , 100%), 584 (Mþ, 29), 293 ([M þ 2ꢃ2þ, 17);
1H NMR (270 MHz, CDCl3) ꢁ 8.20 (d, J ¼ 2:5 Hz, 2H), 8.00 (d,
J ¼ 7:3 Hz, 2H), 7.49 (d, J ¼ 7:3 Hz, 2H), 7.15 (d, J ¼ 2:5 Hz,
2H), 3.55 (s, 4H), 1.47 (s, 18H), 1.24 (s, 18H); 13C NMR
(67.8 MHz, CDCl3) ꢁ 186.22, 149.73, 149.32, 147.92, 147.01,
137.27, 135.45, 135.23, 132.77, 132.32, 128.48, 124.83, 121.90,
36.13, 35.57, 32.27, 29.95, 29.58; IR (KBr) ꢂ 1597 cmꢂ1 (CO);
UV–vis (cyclohexane) ꢃmax 558 (log " ¼ 4:03), 388 (4.59), 272
(4.12), 241 (4.24), 209 (4.63) nm.
fused cyclopentene moiety of 3 (C18–C19, 1.355; C17–C18,
ꢀ
1.483 A) is similar to that in pyracylene 1 (C1–C2, 1.346; C2–
ꢀ
C2a, 1.492 A). Additionally, the central double bond of 3
2
ꢀ
ꢀ
(C25–C26; 1.361 A) is as short as that of 1 (1.360 A). In crystal,
one n-hexane molecule contains for one molecule of 3, which is
positioned between two pyracylene moieties. No significant in-
termolecular interaction between 3 and n-hexane is observed.
The UV–vis spectra of 3 together with 4 are shown in
Figure 2. Semiempirical molecular orbital method (ZINDO) in-
dicates that HOMO of 3 is lower than that of 4 whereas NHOMO
of 3 is higher than that of 4. This is the reason of the hypochro-
mic shift of the first absorption band as well as the bathochromic
shift of the second absorption band in 3. Compound 4 have a
broad absorption in whole visible region. Its concentrated solu-
tion is thus nearly black.
.
The reduction potentials of 3 as well as 4 were measured by
cyclic voltammetry.13 Upon electronic reduction, three reversi-
ble reduction waves were observed for 3 (1E1=2 ¼ ꢂ0:70 V,
12 Crystal data for 3 C6H14 (C48H60O2): Mr 669.00, monoclinic, space
ꢀ
ꢀ
group P21=n (No. 14), a ¼ 11:53ð2Þ A, b ¼ 17:21ð3Þ A, c ¼
ꢁ
ꢀ
ꢀ 3
18:89ð4Þ A, ꢄ ¼ 101:31ð1Þ , V ¼ 3672ð12Þ A , Z ¼ 4, Dcalcd
¼
1:210 g cmꢂ1, Mo Kꢅ (ꢃ ¼ 0:71070 A), 2ꢃmax ¼ 55:0ꢁ; 40135 re-
flections measured, 8373 unique, Rint ¼ 0:080, R1 ¼ 0:045 (2041
data, I > 2ꢆðIÞ), Rw ¼ 0:102, GOF ¼ 0:79, CCDC 285859.
13 V vs Ag/Agþ in 0.1 M n-Bu4NClO4/DMF at 25 ꢁC, scan rate
100 mV sꢂ1, ferrocene/ferrocenium ion = +0.18 V.
ꢀ
3
2E1=2 ¼ ꢂ1:03 V, and E1=2 ¼ ꢂ1:81 V), whereas two waves
for 4 (1E1=2 ¼ ꢂ0:69 V and 2E1=2 ¼ ꢂ1:03 V). The first and sec-
ond potentials of them show the formation of the anion radicals
and dianions. Unlike compound 10,8 this good reversibility re-
Published on the web (Advance View) November 12, 2005; DOI 10.1246/cl.2005.1660