K. Tsuna et al. / Tetrahedron Letters 52 (2011) 7202–7205
7205
Scheme 7. The sequence of hydroboration of 8–10 with 9-BBN and the Liebeskind–Srogl reaction to form medium-sized carbocyclic ketones 11–13.
7. Yu, Y.; Liebeskind, L. S. J. Org. Chem. 2004, 69, 3554–3557.
Acknowledgments
8. Beak, P.; Selling, G. W. J. Org. Chem. 1989, 54, 5574–5580.
9. The highly diluted conditions (0.005 M) were crucial for the goodyield. When the
reaction was carried out using a 0.1 M solution of the substrate, the yield of 5 was
decreased to 45% even under the conditions emplyed in entry 18 of Table 1.
This work was financially supported in part by a Waseda Uni-
versity Grant for Special Research Projects, a Grant-in-Aid for Sci-
entific Research on Innovative Areas (No. 21106009), Young
Scientists (No. 19890231), and the Global COE program ‘‘Center
for Practical Chemical Wisdom’’ by MEXT.
10. Preparation of
5 from 4c: To a stirred solution of S-tert-butyl 3-(2-
allylphenyl)propanethioate 4c (30 mg, 0.114 mmol) in THF (0.23 mL) was
added a solution of 9-BBN in THF (0.57 mL, 0.5 M, 0.285 mmol) dropwise at
30 °C and the resultant solution was stirred until the starting material
disappeared. The reaction was quenched with H2O (0.28 mL) and the
resultant mixture was stirred at room temperature for 5 min. Then, to the
reaction mixture were added THF (22.6 mL), Pd (PPh3)4 (39.6 mg,
3.42 Â 10À2 mmol), Cu (I) thiophene-2-carboxylate (65.4 mg, 0.342 mmol),
and DIPEA (0.04 mL, 0.228 mmol), and the mixture was stirred at 50 °C for
18 h. To the reaction mixture were added Et2O (2 mL), a saturated aqueous
NH4Cl (2 mL) solution, and water (2 mL). The aqueous layer was separated and
extracted with Et2O (2 mL Â 2). The combined organic layers were washed
with brine (2 mL Â 1), dried (Na2SO4), filtered, and concentrated under reduced
pressure. The residue was purified by flash chromatography (hexane/ethyl
acetate = 10/1), and further purification by PTLC (hexane/ethyl acetate = 4/1)
afforded 5,6,9,10-tetrahydrobenzo[8]annulen-7(8H)-one 5 (18.1 mg, 91%). 5:
Rf = 0.48 (hexane/ethyl acetate = 4/1); mp: 42.1–48.7 °C, 1H NMR (400 MHz,
CDCl3) d 7.20–7.10 (4H, m), 3.03 (2H, dd, J = 6.8, 6.3), 2.75 (2H, dd, J = 6.3, 6.1),
2.65 (2H, dd, J = 6.8, 6.3), 2.31 (2H, dd, J = 6.6, 6.3), 1.86–1.80 (2H, m); 13C NMR
(100 MHz, CDCl3) d 214.7, 139.4, 139.1, 129.8, 129.4, 127.4, 126.9, 49.2, 39.8,
32.5, 29.2, 27.2; IR (solid) mmax 3018, 2937, 1701, 1216, 754 cmÀ1; HRMS (EI)
[M]+ calcd for C12H14O: 174.1045, found: 174.1047.
References and notes
1. For the convergent total synthesis of taxol, see: (a) Nicolaou, K. C.; Yang, Z.; Liu,
J. J.; Ueno, H.; Nantermet, P. G.; Guy, R. K.; Claiborne, C. F.; Renaud, J.;
Couladouros, E. A.; Paulvannan, K.; Sorensen, E. J. Nature 1994, 367, 630–634;
(b) Masters, J. J.; Link, J. T.; Snyder, L. B.; Young, W. B.; Danishefsky, S. J. Angew.
Chem., Int. Ed. Engl. 1995, 34, 1723–1726; (c) Doi, T.; Fuse, S.; Miyamoto, S.;
Nakai, K.; Sasuga, D.; Takahashi, T. Chem. Asian J. 2006, 1, 370–383.
2. Gabrielliol, L.; Luigim, A. Acc. Chem. Res. 1977, 10, 95–102.
3. (a) Utsugi, M.; Kamada, Y.; Miyamoto, H.; Nakada, M. Tetrahedron Lett. 2008, 49,
4754–4757; (b) Utsugi, M.; Kamada, Y.; Miyamoto, H.; Nakada, M. Tetrahedron
Lett. 2007, 48, 6868–6872; (c) Kawada, H.; Iwamoto, M.; Utsugi, M.; Miyano,
M.; Nakada, M. Org. Lett. 2004, 6, 4491–4494; (d) Iwamoto, M.; Miyano, M.;
Utsugi, M.; Kawada, H.; Nakada, M. Tetrahedron Lett. 2004, 45, 8653–8657.
4. Liebeskind, L. S.; Srogl, J. J. Am. Chem. Soc. 2000, 122, 11260–11261.
5. Prokopcov, H.; Kappe, C. O. Angew. Chem., Int. Ed. 2009, 48, 2276–2286.
6. (a) Morita, A.; Kuwahara, S. Org. Lett. 2006, 8, 1613–1616; (b) Morita, A.; Kiyota,
H.; Kuwahara, S. Biosci. Biotechnol. Biochem. 2006, 70, 2564–2566.