A. Oota et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 2 (2006)
335
ꢂ4
Formation of Diastereomeric 3b. A solution of 2b (5.74 g,
0 mmol) in acetone (200 mL) was refluxed with a solution of so-
1.97, and 2:06 ꢃ 10 M).
2
Isomerization of 1 in the Presence of Base. A mixture of 1b
(Z=E ¼ 73=27, 23.1 mg, 56 mmol) and KOH (25 mmol in MeOH)
in acetone (5 mL) was stirred at room temperature for 1 h, giving
1b (Z=E ¼ 6=94, 75%) and 6b (12%).
dium iodide (6.00 g, 40 mmol) in acetone (25 mL) for 5.5 h. Upon
usual treatment, 4.1 g of a mixture of meso- and dl-7b (R ¼ Ac)
was obtained. The isomeric ratio of the mixture was accounted
1
to be 51:49 by signal strengths at ꢀ 4.93 and 4.92 ppm of H NMR,
respectively. By fractional recrystallization from ethanol, dl-7b
A mixture of 1c (Z=E ¼ 54=46, 43.1 mg, 50 mmol) and KOH
(25 mmol in MeOH) in acetone (5 mL) was also treated as describ-
ed above, affording 1c (Z=E ¼ 82=18, 82%) and 6c (5%).
A mixture of 1c (Z=E ¼ 62=38, 43.1 mg, 50 mmol) in acetone/
methanol (5 mL/25 mL) was stirred for 1 h: 1c (Z=E ¼ 64=36,
89%) was determined by NMR.
ꢁ
1
was isolated: mp 295–298 C; H NMR ꢀ 2.31 (6H, s), 4.92
2H, s), 7.08 (2H, brs, H8;80 ), 7.35–7.47 (6H, m), 7.62 (2H, d, J ¼
:8 Hz, H4;40 ), 7.76 (2H, d, J ¼ 7:5 Hz, H5;50 ), 7.84 (2H, dd, J ¼
:1, 1.2 Hz, H3;30 ). Anal. Found: C, 87.00; H, 5.39%. Calcd for
C30H22O2: C, 86.93; H, 5.35%.
(
7
8
ꢁ
The mother solution afforded meso-7b: mp 244–246 C;
H NMR ꢀ 2.44 (6H, s), 4.93 (2H, s), 6.98 (2H, brs, H8;80 ), 7.17
2H, t, J ¼ 7:2 Hz, H7;70 ), 7.32 (2H, t, J ¼ 7:5 Hz, H6;60 ), 7.53
2H, brs, H1;10 ), 7.68–7.72 (4H, m), 7.94 (2H, d, J ¼ 7:5 Hz,
T.O. thanks the Ministry of Education, Culture, Sports,
Science and Technology of the Japanese Government for their
financial support (Grants-in-Aid for Scientific Researches on
Priority Areas: Area 767, No. 15085208).
1
(
(
H3;30 ). Anal. Found: C, 86.63; H, 5.28%.
The HPLC chromatograms of meso- and dl-7b showed one and
two peaks, respectively, using a chiral column, Chiralpak-IA.
A mixture of meso- and dl-7b (828 mg, 2.1 mmol) and NBS
(545 mg, 3.1 mmol) in CCl4 (60 mL) was refluxed for 18 h. The
1
precipitate consisted of threo- and erythro-3b (45:55) by H NMR
References
1 H. E. Bronstein, N. Choi, L. T. Scott, J. Am. Chem. Soc.
2002, 124, 8870.
2
893.
3
E. Bergmann, J. Hervey, Ber. Dtsch. Chem. Ges. 1929, 62,
(
ꢀ 5.23 and 5.22 ppm, respectively).
A mixture of meso- and dl-7c (R ¼ St) was obtained quantita-
M. Minabe, K. Suzuki, Bull. Chem. Soc. Jpn. 1975, 48,
tively in a ratio of 49:51 by the similar reaction of 2c. The mixture
of 7c was converted into a mixture of threo- and erythro-3c
586.
4
D. Bethell, J. Chem. Soc. 1963, 666.
D. Bethell, A. F. Cockerill, J. Chem. Soc. B 1966, 917.
D. Bethell, A. F. Cockerill, D. B. Frankham, J. Chem. Soc.
(
47:53).
Rate Measurement on Formation of 1b from 2b. Typical
Procedure: The absorption maxima of 1 were observed at 466
5
6
B 1967, 1287.
4
ꢂ1
ꢂ1
nm with the molar absorptivity of 2:5 ꢃ 10 L mol cm for 1b
7 M. Minabe, T. Oba, M. Tanaka, K. Kanno, M. Tsubota,
Chem. Lett. 2000, 498.
4
ꢂ1
ꢂ1
and 2:2 ꢃ 10 L mol cm for 1c, respectively.
ꢂ5
To a stirred (800 rpm) acetone solution of 2b (8:82 ꢃ 10 M,
8
R. St o¨ sser, J.-U. Thurner, G. Tomaschewski, U. Ewert, P.
ꢂ3
2
M, 0.1 mL) at once. The solution corresponded to a mixture of
2
mation of 1b was estimated to be an increasing absorption at
mL) in an optical cell was added KOH–MeOH (2:67 ꢃ 10
Heblik, W. Schneider, T. Hanke, Z. Naturforsch. A: Phys. Sci.
1982, 37, 1241.
ꢂ5
ꢂ4
b (8:40 ꢃ 10 M) and KOH (1:27 ꢃ 10 M). The rate of for-
9
1797.
J. Schmidt, H. Wagner, Ber. Dtsch. Chem. Ges. 1910, 43,
the initial stage of the reaction. The measurement was repeated
at different KOH concentrations (1.27, 1.69, 2.11, and 2:53 ꢃ
10 Ketone 6a should be formed via air-oxidation of 2, 3, and 1
in the presence of base. A large excess of solvent resulted in an
increase of the oxidized compound 6 (see Run 2 in Table 1). A
part of 6 should be formed via 9-fluorenol that was generated from
2 in the presence of potassium carbonate as a contaminant of
potassium hydroxide.
11 Separation and characterization of the pure threo- and
erythro-3, and the related compounds are now in progress.
12 Colorless or light yellowish 2, 3, 5, and 6 did not give
absorption bands at this wavelength region.
ꢂ4
1
0
M, respectively), and the observed rate was plotted against
the concentration of KOH giving a straight line (correlation co-
efficient = 0.94) of which the slope was the apparent rate con-
stant, as is indicated in Table 3. Also, similar experiments were
carried out at different concentrations of 2b (5.04, 6.72, 8.40, and
ꢂ5
ꢂ4
1
0:1 ꢃ 10 M) and KOH (1:69 ꢃ 10 M).
The reaction of 2c with KOH was done using different concen-
ꢂ5
trations of 2c (4.71, 9.43, and 18:9 ꢃ 10 M) with KOH (1.42,
ꢂ4
1
.64, 2.14, and 2:86 ꢃ 10 M). Also, the following combinations
13 Although recovered 2 in Table 2 suggests the slower reac-
tion of 2c than that of 2b, it is attributable to the poor solubility of
2 (and 1) under the conditions: solubility of 2b and 2c are in the
ꢂ5
were measured: 3b (4.36, 7.63, 10.9, 11.5, and 14:2 ꢃ 10 M)
ꢂ4
with KOH (1.52, 2.02, 2.53, and 3:04 ꢃ 10 M); 3c (4.46, 5.57,
.69, 8.36, and 11:3 ꢃ 10ꢂ5 M) with KOH (1.18, 1.47, 1.67,
orders of magnitudes 10 and 10 M, respectively.
ꢂ5 ꢂ6
6