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K. Tanaka et al.
LETTER
(3) Yamano, S.; Teranishi, M.; Mitsunobu, O. The 74th Meeting
of Chemical Society of Japan, Kyoto, March 30, 1998, 4E5
11
(4) (a) Takai, K.; Ueda, T.; Hayashi, T.; Moriwake, T.
Tetrahedron Lett. 1996, 37, 7049. (b) Takai, K.; Ueda, T.;
Ikeda, N.; Moriwake, T. J. Org. Chem. 1996, 61, 7990.
(5) An optimum conditions for manganese promoted allylation
of cyclododecanone (see ref 4a).
(6) The synthesis of 4-benzoyloxy-2,3-dimethoxyhex-5-enal
(2a) is representative (Table 1, entry 4). Mn powder (138
mg, 2.5 mmol; purchased from Kanto Chemical Co. Inc. Cat.
No. 25061-32) and PbCl2 (42 mg, 0.15 mmol) placed in a
flask were dried by heating with heat-gun in vacuo for 30
min and then THF (1 mL) and TMSCl (0.25 mL, 2.25 mmol)
were successively added. The resulting mixture was stirred
for 30 min, followed by the addition of 1a (218 mg, 0.5
mmol) in THF (1.5 mL). After 45 min, the mixture was
filtered through Hyfro Super Cel®. The flask was rinsed with
ethyl acetate and the mixture was filtered through the Hyfro
Super Cel®. The filtrate was washed with H2O. The organic
layer was dried (MgSO4) and concentrated under reduced
pressure. The residue was separated by silica gel column
chromatography (hexane:AcOEt = 3:2) to afford 2a (134
mg, 96%). 1H NMR (270 MHz; in CDCl3): 9.84 (1H, d,
J = 1.37 Hz, H-1), 8.09-8.04 (2H, m, Ph), 7.60-7.45 (3H, m,
Ph), 5.96 (1H, ddd, J = 17.41, 10.54, 6.41 Hz, H-5), 5.85-
5.81 (1H, m, H-4), 5.48 (1H, ddd, J = 17.41, 1.37, 0.92 Hz,
H-6a), 5.36 (1H, ddd, J = 10.54, 1.37, 0.92 Hz, H-6b), 3.62
(1H, dd, J = 6.41, 3.21 Hz, H-3), 3.39 (1H, dd, J = 3.21, 1.37
Hz, H-2), 3.52 (3H, s, CH3O), 3.49 (3H, s, CH3O).
(7) Reduction of 2a by NaBH4: To a solution of 2a (100 mg,
0.36 mmol) in ethanol (1 mL) was added NaBH4 (27 mg,
0.72 mmol) at 0 °C. After the solution was stirred at 0 °C for
2 h, the reaction was quenched by the addition of 5% HCl.
The mixture was extracted with ethyl acetate. The organic
layer was separated, dried (MgSO4), and concentrated. The
residue was separated by silica gel column chromatography
(ethyl acetate:hexane = 1:1) to give alcohol 3a (62 mg,
61%). 1H NMR (500 MHz) In CDCl3: 8.09-8.07 (2H, m,
Ph), 7.60-7.44 (3H, m Ph), 6.01 (1H, ddd, J = 16.95, 11.00,
6.42 Hz, H-5), 5.78-5.75 (1H, m, H-4), 5.44 (1H, dt,
J = 16.45, 1.37 Hz, H-6a), 5.32 (1H, dt, J = 11.00, 1.37 Hz,
H-6b), 3.87 (1H, dd, J = 11.46, 4.58 Hz, H-1a), 3.70 (1H, dd,
J = 11.46, 4.58 Hz, H-1b), 3.60-3.58 (1H, m, H-3), 3.45 (1H,
q, 4.58, H-2), 3.59 (3H, s, CH3O), 3.50 (3H, s, CH3O). In
C6D6: 8.22-8.20 (2H, m, Ph), 7.10-7.01 (3H, m, Ph), 6.05
(1H, ddt, J = 5.96, 4.58, 1.37 Hz, H-4), 5.93 (1H, ddd,
J = 17.41, 10.54, 5.96 Hz, H-5), 5.36 (1H, dt, J = 17.4, 1.37
Hz, H-6a), 5.05 (1H, dt, J = 10.54, 1.37 Hz, H-6b), 3.71-3.69
(1H, m, H-1a), 3.57-3.54 (1H, m, H-1b), 3.47 (1H, dd,
J = 5.96, 4.59 Hz, H-3), 3.26 (1H, dt, J = 5.96, 4.58 Hz,
H-2), 3.31 (3H, s, CH3O), 3.14 (3H, s, CH3O).
Synlett 2001, No. 10, 1620–1622 ISSN 0936-5214 © Thieme Stuttgart · New York