9868
Acknowledgements
We thank the National Science Council of the Republic of China for financial support.
References
1. For 1,5-hydrogen atom transfer from sp3 to sp2 carbons followed by radical cyclization, see: (a) Lathbury, D. C.;
Parsons, D. J.; Pinto, I. J. Chem. Soc., Chem. Commun. 1988, 81. (b) Curran, D. P.; Kim, D.; Liu, H. T.; Shen,
W. J. Am. Chem. Soc. 1988, 110, 5900. (c) Snieckus, V.; Cuevas, J.-C.; Sloan, C. P.; Liu, H.; Curran, D. P. J. Am.
Chem. Soc. 1990, 112, 896. (d) Borthwick, A. D.; Caddick, S.; Parsons, P. J. Tetrahedron Lett. 1990, 31, 6911. (e)
Curran, D. P.; Abraham, A. C.; Liu, H. J. Org. Chem. 1991, 56, 4335. (f) Borthwick, A. D.; Caddick, S.; Parsons,
P. J. Tetrahedron 1992, 48, 10655. (g) Brown, C. D. S.; Simpkins, N. S. Tetrahedron Lett. 1993, 34, 6911. For
1,5-hydrogen atom transfer from sp3 carbons to oxygen radicals followed by radical addition reactions, see: (h)
Petrovic, G.; Cekovic, Z. Tetrahedron 2000, 55, 1377. (i) Tsunoi, S.; Ryu, I.; Ohuda, T.; Tanaka, M.; Komatsu,
M.; Sonoda, N. J. Am. Chem. Soc. 1998, 120, 8692 and references cited therein.
2. (a) Sha, C.-K.; Jean, T.-S.; Wang, D.-C. Tetrahedron Lett. 1990, 31, 3745. (b) Sha, C.-K.; Chiu, R.-T.; Yang,
C.-F.; Yao, N.-T.; Tseng, W.-H.; Liao, F.-L.; Wang, S.-L. J. Am. Chem. Soc. 1997, 119, 4130. (c) Sha, C.-K.;
Santhosh, K. C.; Lih, S.-H. J. Org. Chem. 1998, 63, 2699. (d) Sha, C.-K.; Lee, F.-K.; Chang, C.-J. J. Am. Chem.
Soc. 1999, 121, 9875.
3. Kamiya, N.; Chikami, Y.; Ishii, Y. Synlett 1990, 675.
4. (a) The steps for the preparation of compounds 12, 13 and 15–18 are shown in the following scheme:
E
E
i) n-BuLi
ii) ClCO2Me
or
NaI, HOAc 4c
or
i) n-BuLi
ii) ROTf or RI
O
O
O
O
O
(CH2)m
( )n
(CH2)m
(CH2)m
I
6, 7
( )n
( )n
57% HI 4d
ZnI2,TsCN 4b
iii) HOCH2CH2OH
p-TSA
12, 13, 15-18
E = CO2Me or CN
27
26
(b) For ZnI2/TsCN reaction, see: Bedford, C. D.; Harris, R. N.; Howd, R. A.; Goff, D. A.; Koolpe, G. A. J. Med.
Chem. 1989, 32, 1504. (c) For NaI/HOAc reaction, see: Lu, X.; Ma, S. J. Chem. Soc., Chem. Commun. 1990, 1643;
Lu, X.; Ma, S. Tetrahedron Lett. 1990, 31, 7653; Marek, I.; Alexakis, A.; Normant, J. F.; Tetrahedron Lett. 1991,
32, 5329; Lu, X.; Ma, S. J. Org. Chem. 1992, 57, 709; Piers, E.; Wong, T.; Coish, P. D.; Rogers, C. Can. J. Chem.
1994, 72, 1816; Luo, F.-T.; Hsieh, L.-C. J. Chin. Chem. Soc. 1994, 41, 871; Klement, I.; Lennick, K.; Tucker, C.
E.; Knochel, P. Tetrahedron Lett. 1993, 34, 4623. (d) For 57% HI reaction, see: Chalchat, J. C.; Duteurtre, P.;
Theron, F.; Vessiere, R. C. Acad. Sci., Ser. C 1971, 273, 832.
5. (a) Compound 14 was prepared from compound 28 according to the following scheme:
O
5c
O
O
I
i) CBr4, PPh3
i) Me2CuLi
ii) HOCH2CH2OH, p-TSA
CHO
CO2Me
CO2Me
ii) n-BuLi, ClCO2Me
iii) NaI, HOAc4c
iii) LAH
iv) PCC
285b
75% trans:cis = 4:1
14
74%
29
(b) For the preparation of starting material 28, see: Hwu, J.-R.; Hakimelahi, G.; Chou, C.-T. Tetrahedron Lett.
1992, 33, 6469. (c) For CBr4/PPh3 reaction, see: Corey, E. J.; Fuchs, P. L. Tetrahedron Lett. 1972, 3769.
6. All new compounds gave satisfactory spectral data. A general procedure for 1,5-hydrogen atom transfer/radical
cyclization: To a refluxing solution of 16 (61.1 mg, 0.2 mmol) in dry toluene (15 mL) was added a solution of
Bu3SnH (0.066 mL, 0.25 mmol) and AIBN (4 mg, 0.024 mmol) in dry toluene (4.8 mL) with a syringe pump (0.5
mL h−1). After addition, the reaction mixture was heated under reflux for 1 h. The solvent was then removed using
a rotary evaporator. Et2O (20 mL) and DBU (0.04 mL, 0.27 mmol) were added. In order to remove the organotin
compounds, a solution of iodine (1 M in Et2O) was added dropwise to give a white solid. After the iodine color