R. Hamasaki et al. / Tetrahedron 56 (2000) 7423–7425
7425
ether40:1) to give the desired b-ketoester (2; 1.43 g,
93%). Pale yellow oil. 1H NMR (300 MHz, CDCl3) d
1.21–1.43 (16H, m), 1.51–1.63 (2H, m), 1.78–1.89 (2H,
m), 1.99–2.07 (4H, m), 2.39–2.60, (2H, m), 3.43 (0.97H,
t, J7.4 Hz; keto form), 3.71 (2.91H, s; keto form), 3.75
(0.09H, s; enol form), 4.90–5.03 (4H, m), 5.72–5.87 (2H,
m). 13C NMR (75 MHz, CDCl3) d 23.37, 27.37, 28.19,
28.70, 28.78, 28.83, 28.91, 29.11, 29.13, 33.62, 33.67,
41.77, 52.14, 58.94, 114.14, 114.18, 138.89, 138.96,
NMR (400 MHz, CDCl3) d 1.16–1.41 (16H, m), 1.53–
1.67 (4H, m), 1.95–2.07 (4H, m), 2.37 (1.5H, t, J7.1 Hz;
E form), 2.40 (0.5H, t, J6.7 Hz; Z form), 5.25–5.39 (2H,
m). 13C NMR (100 MHz, CDCl3) E-form; d 23.98, 27.38,
28.32, 28.74, 28.79, 31.91, 42.45, 130.93, 213.13. Z-form; d
23.83, 26.66, 28.10, 28.18, 28.57, 29.00, 42.41, 130.12,
212.50. IR (neat) 2928, 2855, 1713 cmϪ1
.
[Method B]
170.34, 205.27. IR (neat) 2928, 2857, 1748, 1717 cmϪ1
.
Anal. Calcd for C21H36O3: C, 75.0; H, 10.8. Found: C,
74.7; H, 10.6.
TiCl4 (1.0 M solution in toluene; 0.90 ml) was added to a
stirred solution of 1 (111 mg, 0.6 mmol) and Bu3N (200 mg,
1.08 mmol) in toluene (2.6 ml) at 0–5ЊC. The mixture was
stirred for 1 h followed by addition of toluene (76 ml).
Then, Grubbs’ reagent (5; 49 mg, 0.06 mmol) in toluene
(0.5 ml) was added to the reaction mixture at 110ЊC for a
few min. The mixture was stirred for 8 h by monitoring with
TLC, and then was quenched with water (20 ml). After
evaporation of toluene, the residue was extracted twice
with ether. The combined organic phase was washed with
water, brine, dried (Na2SO4) and concentrated. The obtained
crude oil was purified by SiO2-column chromatography
(30:1!20:1) to give civetone (4; 36 mg, 48%).
(NaH-Claisen method) 1 (369 mg, 2.00 mmol) in strictly
dried (benzophenone-ketyl) DME (3.6 ml) was added to a
stirred powder of NaH (82 mg, 3.40 mmol) at 20–25ЊC for
5 min. The mixture was refluxed for 20 h and cooled down.
A small amount of water and 1 M aqueous HCl (20 ml) were
successively added to this mixture. The organic phase was
extracted twice with ether, which was washed with water,
brine, dried (Na2SO4) and concentrated. The obtained crude
oil was purified by SiO2-column chromatography (hexane:
ether20:1) to give the desired b-ketoester (2; 254 mg,
75%) along with 9-decenoic acid (81 mg, 24%).
2-Methoxycarbonyl-9-cycloheptadecenone (3)
[Method A]
Acknowledgements
We appreciate the helpful discussion with Mr Atsushi
Makita of Japan-Energy Co. Ltd. This work was partially
supported by a Grant-in-Aid for Scientific Research from
the Ministry of Education, Science, Sports and Culture
(Japan).
The Grubbs’ reagent, bis(tricyclohexylphosphine)benzil-
idene ruthenium dichloride (5; 25 mg, 0.03 mmol) in
toluene (1.0 ml) was added dropwise to a stirred solution
of 2 (101 mg, 0.3 mmol) in toluene (79 ml) at 110ЊC for a
few minutes. The mixture was stirred at that temperature for
2 h, then the solvent was removed in vacuum. The residue
was purified by SiO2-column chromatography (hexane:
EtOAc40:1!20:1) to give the desired b-ketoester 3
(78 mg, 84%; E:Zca. 3:1). Pale yellow oil. 1H NMR
(400 MHz, CDCl3) d 1.14–1.45 (16H, m), 1.51–1.71 (2H,
m), 1.73–2.11 (6H, m), 2.45–2.56 (2H, m), 3.49 (0.25H, dd,
J9.0 Hz, J5.4 Hz; Z form), 3.51 (0.75H, dd, J8.7 Hz,
J6.2 Hz; E form), 3.70 (3H, s), 5.25–5.39 (2H, m). 13C
NMR (100 MHz, CDCl3) E-form; d 23.40, 27.19, 27.37,
27.41, 27.84, 28.30, 28.40, 28.60, 28.70, 28.84, 31.84,
41.43, 52.20, 58.35, 130.85, 131.08, 170.16, 206.73. Z
form; d 23.35, 26.58, 26.79, 27.05, 27.96, 28.00, 28.08,
28.15, 28.35, 28.45, 28.98, 29.01, 41.54, 52.24, 58.42,
130.07, 130.15, 170.24, 206.36. IR (neat) 2928, 2855,
References
1. Sack, H. Chemiker Z. 1915, 39, 538.
2. For a recent review: Williams, A. S. Synthesis 1999, 170.
3. (a) Tsuji, J.; Hashiguchi, S. Tetrahedron Lett. 1980, 2955;
J. Organomet. Chem. 1981, 218, 69. (b) Tsuji, J.; Mandai, T.
Tetrahedron Lett. 1977, 3285.
4. Choo, Y.-M.; Ooi, K.-E.; Ooi, I.-H. J. Am. Oil Chem. Soc. 1994,
71, 911. This paper describes that the Dieckmann cyclization using
KH required a strict procedure; careful dried conditions (especially
for THF solvent) were necessary, otherwise considerable amounts
of hydrolysis of diesters were detected. See also Ref. 9.
5. Reviews: (a) Grubbs, R. H.; Miller, S. J.; Fu, G. C. Acc. Chem.
Res. 1995, 28, 446. (b) Schmalz, H.-G. Angew. Chem., Int. Ed.
Engl. 1995, 34, 1833. (c) Armstrong, S. K. J. Chem. Soc., Perkin
Trans. 1 1998, 371.
1750, 1715 cmϪ1
.
Civetone (4; 9-cycloheptadecenone) [Method A]
According to the reported procedure,4 a mixture of b-keto-
ester (3; 247 mg, 0.8 mmol) in 5% aqueous NaOH–MeOH–
THF (6.5 ml:13 ml:6.5 ml) was stirred at 70ЊC for 5 h. After
cooling to 0ЊC, 10% aqueous H2SO4 was added to the
mixture (slightly acidic), which was refluxed for 10 min.
After evaporation of the solvent, the residue was extracted
with ether. The organic phase was washed with water, brine,
dried (Na2SO4) and concentrated. The obtained crude oil
was purified by SiO2-column chromatography (hexane:
ether30:1!20:1) to give civetone (4; 9-cycloheptadece-
6. Plugge, M. F. C.; Mol, J. C. Synlett 1991, 507.
7. (a) Tanabe, Y. Bull. Chem. Soc. Jpn 1988, 62, 1917. (b) Yoshida,
Y.; Hayashi, R.; Sumihara, H.; Tanabe, Y. Tetrahedron Lett. 1997,
38, 8727. (c) Yoshida, Y.; Matsumoto, N.; Hamasaki, R.; Tanabe, Y.
Tetrahedron Lett. 1999, 40, 4227. For the practically mild conditions
(not Ϫ78ЊC but 0ЊC—an ambient temp.), TMSCl or TMSOTf
catalyst did not show a significant effect.
8. Shuwab, P.; France, M. B.; Ziller, J. W.; Grubbs, R. H. Angew.
Chem., Int. Ed. Engl. 1995, 34, 2039.
9. McMurry, J. E.; Fleming, M. P.; Kees, K. L.; Krepski, L. R.
J. Org. Chem. 1978, 17, 3255.
1
none; 190 mg, 95%; E:Zca. 3:1). Colorless crystals. H