1712
M. Sreekanth et al. / Tetrahedron Letters 52 (2011) 1709–1712
9. Maryanoff, B. E.; Reitz, A. B. Chem. Rev. 1989, 89, 863–927.
10. Lindsay, K. B.; Pyne, S. G. J. Org. Chem. 2002, 67, 7774–7780.
11. Guo, H.; O’Doherty, G. A. Org. Lett. 2005, 7, 3921–3924.
12. Nicolaou, K. C.; Prasad, C. V. C.; Somers, P. K.; Hwang, C. K. J. Am. Chem. Soc.
1989, 111, 5330–5334.
13. Wipf, P.; Graham, T. H. J. Am. Chem. Soc. 2004, 126, 15346–15347.
14. Mancuso, A. J.; Huang, S.-L.; Swern, D. J. Org. Chem. 1978, 43, 2480–2482.
15. (a) Luche, J. L. J. Am. Chem. Soc. 1978, 100, 2226–2227; (b) Gemal, A. L.; Luche, J.
L. J. Am. Chem. Soc. 1981, 103, 5454–5459.
were fixed in a single-step radical mediated reaction is notewor-
thy. Further studies are underway in the laboratory in order to ex-
tend this work for the application in the synthesis of natural
products and will be reported in due course.
Acknowledgments
16. Generalized experimental procedure for Ti(III) radical mediated epoxide opening
reaction: Activated Zn powder (6 equiv), freshly fused ZnCl2 (3 equiv) and
Cp2TiCl2 (3 equiv) were taken in anhydrous THF (15 mL/mmol of substrate)
and stirred for 30 min at room temperature. The color of the reaction mixture
turned into deep green from deep red. Then it was cooled to ꢀ20 °C and a
solution of 2,3-epoxy alcohol 6A–D (1 equiv) in anhydrous THF was introduced
via cannula. The reaction mixture was then slowly allowed to attain room
temperature over a period of 2 h and stirred for additional 14 h before it was
quenched with 1 N HCl and then extracted with ethyl acetate. The combined
organic extracts were washed with saturated aqueous NaHCO3, water,
saturated NaCl, dried over anhydrous Na2SO4 and concentrated in vacuo.
Purification by using standard silica gel column chromatography (22–28%
ethyl acetate in petroleum ether eluant) afforded the five-membered
carbocycles 7A–D.
The authors wish to thank DST, New Delhi for the Ramanna
Fellowship (SR/S1/RFOC-06/2006; T.K.C.) and CSIR, New Delhi for
research fellowships (M.S., G.P.). Helpful discussion with Dr. Rajar-
shi Samanta, Max-Planck-Institut für molekulare Physiologie, Dort-
mund is greatly acknowledged.
References and notes
1. (a) Togo, H. Advanced Free Radical Reactions for Organic Synthesis; Elsevier, 2004;
b Marco-Contelles, J.; Ruiz, P.; Martínez, L.; Martínez-Grau, A. Tetrahedron
1993, 49, 6669–6694; (c) Jasperse, C. P.; Curran, D. P.; Fevig, T. L. Chem. Rev.
1991, 91, 1237–1286; (d) Ramaiah, M. Tetrahedron 1987, 43, 3541–3676; (e)
Hart, D. J. Science 1984, 223, 883–887.
2. (a) RajanBabu, T. V.; Nugent, W. A. J. Am. Chem. Soc. 1994, 116, 986–997; (b)
RajanBabu, T. V.; Nugent, W. A.; Beattie, M. S. J. Am. Chem. Soc. 1990, 112, 6408–
6409; (c) RajanBabu, T. V.; Nugent, W. A. J. Am. Chem. Soc. 1989, 111, 4525–
4527; (d) Nugent, W. A.; RajanBabu, T. V. J. Am. Chem. Soc. 1988, 110, 8561–
8562; (e) Gansäuer, A.; Bluhm, H. Chem. Rev. 2000, 100, 2771–2788.
3. (a) Chakraborty, T. K.; Das, S. Tetrahedron Lett. 2002, 43, 2313–2315; (b)
Chakraborty, T. K.; Dutta, S. J. Chem. Soc., Perkin Trans. 1 1997, 1257–1260; (c)
Chakraborty, T. K.; Samanta, R.; Das, S. J. Org. Chem. 2006, 71, 3321–3324; (d)
Chakraborty, T. K.; Samanta, R.; Ravikumar, K. Tetrahedron Lett. 2007, 48, 6389–
6392; (e) Chakraborty, T. K.; Samanta, R.; Roy, S.; Sridhar, B. Tetrahedron Lett.
2009, 50, 3306–3310.
4. For some representative works, see: (a) Chakraborty, T. K.; Chattopadhyay, A.
K.; Samanta, R.; Ampapathi, R. S. Tetrahedron Lett. 2010, 51, 4425–4428; (b)
Chakraborty, T. K.; Samanta, R.; Kumar, P. K. Tetrahedron 2009, 65, 6925–6931;
(c) Chakraborty, T. K.; Purkait, S. Tetrahedron Lett. 2008, 49, 5502–5504; (d)
Chakraborty, T. K.; Goswami, R. K.; Sreekanth, M. Tetrahedron Lett. 2007, 48,
4075–4078; (e) Chakraborty, T. K.; Chattopadhyay, A. K.; Ghosh, S. Tetrahedron
Lett. 2007, 48, 1139–1142; (f) Chakraborty, T. K.; Reddy, V. R. Tetrahedron Lett.
2006, 47, 2099–2102; (g) Chakraborty, T. K.; Sudhakar, G. Tetrahedron Lett.
2006, 47, 5847–5849; (h) Chakraborty, T. K.; Ghosh, S.; Laxman, P.; Dutta, S.;
Samanta, R. Tetrahedron Lett. 2005, 46, 5447–5450; (i) Chakraborty, T. K.;
Reddy, V. R.; Reddy, T. J. Tetrahedron 2003, 59, 8613–8622; (j) Chakraborty, T.
K.; Tapadar, S. Tetrahedron Lett. 2003, 44, 2541–2543; (k) Chakraborty, T. K.;
Das, S.; Raju, T. V. J. Org. Chem. 2001, 66, 4091–4093; (l) Chakraborty, T. K.; Das,
S. J. Indian Chem. Soc. 1999, 76, 611–616.
17. Analytical and spectral data of five-membered carbocycles. Compound 7A: Rf = 0.3
(silica gel, 40% ethyl acetate in hexane); ½a D24
ꢂ
= +28.1 (c 1.43, CHCl3); IR (neat):
mmax 3357 (br), 2963, 2924, 1729, 1372, 1298, 1256, 1171, 1115, 1030,
;
952 cmꢀ1 1H NMR (400 MHz, CDCl3): d 4.52 (td, J = 4.7,1.5 Hz, 1H, C1H), 4.14
(q, J = 7.2 Hz, 2H, COOCH2CH3), 3.97 (qd, J = 6.5, 4 Hz, 1H, C6H), 2.61 (m, 1H,
C3H), 2.40 (dd, J = 16, 6.5 Hz, 1H, C8Hb), 2.34 (dd, J = 16, 7.3 Hz, 1H, C8H ), 2.13
a
(m, 1H, C4Hb), 1.8 (m, 1H, C5H ), 1.67 (m, 1H, C5Hb), 1.37 (d, J = 6.5 Hz, 3H,
a
C7H3), 1.34 (m, 1H, C4H ), 1.32 (dt, J = 10.3, 4.3 Hz, 1H, C2H), 1.26 (t, J = 7.2 Hz,
a
3H, COOCH2CH3); 13C NMR (100 MHz, CDCl3): d 173.9, 74.7, 66.8, 60.6, 56.1,
38.8, 34.0, 33.4, 29.3, 21.9, 14.2; ESI-MS: m/z (%) 217 (95) [M+H]+, 239 (100)
[M+Na]+; HRMS (ESI): calcd for C11H20O4Na [M+Na]+ 239.1259, found
239.1265; Compound 7B: Rf = 0.3 (silica gel, 50% ethyl acetate in hexane);
½
a 2D4
ꢂ
= +26.3 (c 0.95, CHCl3); IR (neat):
mmax 3358 (br), 2969, 2934, 1728, 1452,
1376, 1254, 1180, 1047 cmꢀ1 1H NMR (400 MHz, CDCl3): d 4.53 (td, J = 4.6,
;
2.3 Hz, 1H, C1H), 4.12 (q, J = 7.1 Hz, 2H, COOCH2CH3), 4.0 (qd, J = 6.4, 4 Hz, 1H,
C6H), 2.61 (qd, J = 7.1, 4.8 Hz, 1H, C8H), 2.54 (m, 1H, C3H), 1.99 (m, 1H, C4Hb),
1.72 (m, 1H, C5H ), 1.64 (m, 1H, C5Hb), 1.56 (dt, J = 8.8, 4.4 Hz, 1H, C2H), 1.51
a
(m, 1H, C4H ), 1.37 (d, J = 6.5 Hz, 3H, C7H3), 1.2 (t, J = 7.2 Hz, 3H, COOCH2CH3),
a
1.17 (d, J = 7 Hz, 3H, C9H3); 13C NMR (100 MHz, CDCl3): d 176.2, 75.2, 67.5, 60.3,
51.9, 40.9, 40.0, 33.6, 25.7, 22.3, 14.7, 14.3; ESI-MS: m/z (%) 231 (100) [M+H]+,
253 (50) [M+Na]+; HRMS (ESI): calcd for C12H22O4Na [M+Na]+ 253.1415, found
253.1427; Compound 7C: Rf = 0.4 (silica gel, 60% ethyl acetate in hexane);
½
a 2D4
ꢂ
= +20.7 (c 0.41, CHCl3); IR (neat):
mmax 3391 (br), 2926, 1721, 1652, 1256,
1105, 1038, 747 cmꢀ1 1H NMR (400 MHz, CDCl3): d 7.38–7.20 (m, 5H, ArH),
;
4.52 (s, 2H, PhCH2), 4.35 (td, J = 5.3, 2.5 Hz, 1H, C1H), 4.03 (q, J = 7.4 Hz, 2H,
COOCH2CH3), 3.96 (m, 1H, C6H), 3.6 (d, J = 5 Hz, 2H, C7H2), 2.56 (m, 1H, C3H),
2.35 (dd, J = 15.4, 5.4 Hz, 1H, C8Hb), 2.17 (dd, J = 15.4, 8.5 Hz, 1H, C8Ha), 2.05 (m,
5. For the preparation of highly functionalized five-membered carbocycles, even
though a wide variety of methods were found, select methods are mentioned
here. For example: transformation of carbohydrates to cyclopentanes, see: (a)
Ferrier, R. J.; Middleton, S. Chem. Rev. 1993, 93, 2779–2831; (b) Borthwick, A.
D.; Biggadike, K. Tetrahedron 1992, 48, 571–623; (c) Berecibar, A.; Grandjean,
C.; Siriwardena, A. Chem. Rev. 1999, 99, 779–844; (d) Martínez-Grau, A.; Marco-
Contelles, J. Chem. Soc. Rev. 1998, 27, 155–162; (e) Marco-Contelles, J.;
Alhambra, C.; Martínez-Grau, A. Synlett 1998, 693–699; (f) Dalko, P. I.; Sinaÿ,
P. Angew. Chem., Int. Ed. 1999, 38, 773–777; For transition metal mediated C–C
bond forming reactions, see: (g) Takahashi, K.; Honda, T. Org. Lett. 2010, 12,
3026–3029. and the references cited therein.; For intramolecular [3+2]
cycloaddition reactions, see: (h) Reissig, H.-U.; Zimmer, R. Chem. Rev. 2003,
103, 1151–1196; (i) Yu, M.; Pagenkopf, B. L. Tetrahedron 2005, 61, 321–347.
6. (a) Toshima, H.; Ichihara, A. In Biologically Active Natural Products; Cutler, H. G.,
Cutler, S. J., Eds.; CRC press, 1999. Chapter 8: Coronatine; (b) Nonaka, H.;
Ogawa, N.; Maeda, N.; Wang, Y.-G.; Kobayashi, Y. Org. Biomol. Chem. 2010, 8,
5212–5223.
1H, C4Hb), 1.76 (m, 1H, C5H ), 1.58 (m, 1H, C5Hb), 1.46 (dt, J = 9.7, 4.8 Hz, 1H,
a
C2H), 1.24 (m, 1H, C4H ), 1.15 (t, J = 7.4 Hz, 3H, COOCH2CH3); 13C NMR
a
(100 MHz, CDCl3): d 173.2, 137.7, 128.6, 127.9, 127.8, 74.9, 73.8, 73.6, 70.3,
60.4, 51.6, 38.9, 34.9, 33.6, 29.0, 14.2; ESI-MS: m/z (%) 323 (70) [M+H]+, 340
(20) [M+NH4]+, 345 (100) [M+Na]+; HRMS (ESI): calcd for C18H26O5Na [M+Na]+
345.1677, found 345.1669; Compound 7D: Rf = 0.5 (silica gel, 50% ethyl acetate
in hexane); ½a 2D4
ꢂ
= +28.9 (c 0.84, CHCl3); IR (neat): mmax 3391 (br), 2930, 1720,
1452, 1264, 1176, 1100, 1041, 740, 700 cmꢀ1
;
1H NMR (400 MHz, CDCl3): d
7.38–7.26 (m, 5H, ArH), 4.52 (s, 2H, PhCH2), 4.35 (td, J = 5.1, 2.6 Hz, 1H, C1H),
4.03 (q, J = 7.2 Hz, 2H, COOCH2CH3), 4.00 (m, 1H, C6H), 3.6 (d, J = 5.4 Hz, 2H,
C7H2), 2.56 (qd, J = 7.2, 5.09 Hz, 1H, C8H), 2.44 (m, 1H, C3H), 1.92 (m, 1H, C4Hb),
1.69 (m, 1H, C2H), 1.66 (m, 1H, C5H ), 1.58 (m, 1H, C5Hb), 1.42 (m, 1H, C4H ),
a
a
1.15 (t, J = 7.1 Hz, 3H, COOCH2CH3), 1.1 (d, J = 7.1 Hz, 3H, C9H3); 13C NMR
(100 MHz, CDCl3): d 175.6, 137.6, 128.5, 127.9, 127.8, 75.3, 74.0, 73.6, 70.8,
60.2, 48.3, 41.3, 41.0, 33.6, 25.3, 15.5, 14.3; ESI-MS: m/z (%) 337 (100) [M+H]+,
359 (95) [M+Na]+; HRMS (ESI): calcd for C19H28O5Na [M+Na]+ 359.1834, found
359.1820.
7. (a) Dinda, B.; Debnath, S.; Harigaya, Y. Chem. Pharm. Bull. 2007, 55, 159–222; (b)
Tundis, R.; Loizzo, M. R.; Menichini, F.; Statti, G. A.; Menichini, F. Mini Rev. Med.
Chem 2008, 8, 399–420; (c) El-Naggar, L. J.; Beal, J. L. J. Nat. Prod. 1980, 43, 649–
707; (d) Miersch, O.; Bohlmann, H.; Wasternack, C. Phytochemistry 1999, 50,
517–523; (e) Bianco, A. Pure Appl. Chem. 1994, 66, 2335–2338.
18. (a) Jeener, J.; Meier, B. H.; Bachmann, P.; Ernst, R. R. J. Chem. Phys. 1979, 71,
4546–4553; (b) Consistent pattern of a cis-junction has been observed in the
formation of five-membered targets and a trans-junction in six-membered
targets during our previous Ti(III) mediated epoxide opening reactions. See:
Refs. 3c–e and 4a.
8. Gao, Y.; Klunder, J. M.; Hanson, R. M.; Masamune, H.; Ko, S. Y.; Sharpless, K. B. J.
Am. Chem. Soc. 1987, 109, 5765–57801.