Total synthesis of (+)-komarovispirone

Organic Letters

Volumn 10, Issue 1, 2008, Pages 89-91

  Majetich, George ^a   Yu, Jianhua ^a  

^a UNIVERSITY OF GEORGIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

DITERPENE; KOMAROVIQUINONE; QUINONE DERIVATIVE; UNCLASSIFIED DRUG;

ARTICLE; CHEMICAL STRUCTURE; CHEMISTRY; STEREOISOMERISM; SYNTHESIS;

DITERPENES; MOLECULAR STRUCTURE; QUINONES; STEREOISOMERISM;

EID: 38349132335     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol7017449     Document Type: Article

References (20)

1. Vvednski, A. I. Flora Uzbekistana; Editio Academiae Scientiarum USSR: Tashkent, 1961; Vol. 5, p 313.
2. (a) Uchiyama, N.; Kiuchi, F.; Ito, M.; Honda, G.; Takeda, Y.; Khodzhimatov, O. K.; Ashurmetov, O. A. J. Nat. Prod. 2003, 66, 128-131.
3. (b) For the isolation of coulterone from other plants, see: Frontana, B.; Cardenas, J.; Rodriguez-Hahn, L. Phytochemistry 1994, 36, 739-741.
4. Uchiyama, N.; Ito, M.; Kiuchi, F.; Honda, G.; Takeda, Y.; Khodzhimatov, O. K.; Ashurmetov, O. A. Tetrahedron Lett. 2004, 45, 531-533.
5. 5 komaroviquinone is the most potent with a minimum lethal concentration (MLC) of 0.4 μM., which contrasts with a MLC of 23.0 μM for komarovispirone.
6. Bastien, J. W. The Kiss of Death, Chagas' Disease in the Americas; University of Utah Press: Salt Lake City, UT, 1998.
7. For other strategies to prepare the icetexane skeleton of 1, see: (a) Padwa, A.; Boonsombat, J.; Rashatasakhon, P.; Willis, J. Org. Lett. 2005, 7, 3725-3727.
8. (b) Simmons, E. M.; Sarpong, R. Org. Lett. 2006, 8, 2883-2886.
9. (c) Srikrishna, A.; Beeraiah, B. Tetrahedron Lett. 2007, 48, 2291-2294.
10. The spectroscopic data obtained for all new compounds were fully consistent with the assigned structures. Reaction conditions have not been optimized.
11. (a) For the first synthesis of (±)-komaroviquinone (1), see: Sengupta, S.; Drew, M. G. B.; Mukhopadhyay, R.; Achari, B.; Banerjee, A. K. J. Org. Chem. 2005, 70, 7694-7700.
12. (b) For our synthesis of (±)-komaroviquinone, see: Majetich, G.; Li, Y.; Zou, G. Heterocycles 2007, 75, 217-225.
13. For a synthesis of (+)-komaroviquinone, see: Majetich, G.; Yu, J.; Li, Y. Heterocycles 2007, 73, 227-235.
14. f 3 = 0.55, hexanes/EtOAc = 4:1).
15. Penn, J. H.; Orr, R. D. J. Chem. Educ. 1989, 66, 86-88.
16. Scheme 2 depicts only the excitation of the C(11) carbonyl of 1 prior to the generation of diradical species iii. If the C(14) carbonyl, a vinylogous ester, is the dominant chromophore, its excitation also results in the intermediacy of iii, as shown below. Figure presented.
17. Hurst, J. J.; Whitham, G. H. J. Chem. Soc. 1960, 2864-2869.
18. (a) Zimmerman, H. E.; Lewis, R. G.; McCullough, J. J.; Padwa, A.; Staley, S.; Semmelhack, M. J. Am. Chem. Soc. 1966, 88, 159-161.
19. (b) Chapman, O. L.; Sieja, J. B.; Welstead, W. J., Jr. J. Am. Chem. Soc. 1966, 88, 161-162.
20. Komarovispirone was isolated as a minor component from a side fraction of a silica gel column in which komaroviquinone was isolated as the major component. It has been suggested that komarovispirone may be produced via the proposed photochemical pathway while still in aerial parts of the semi-shrub Dracocephalum komarovi Lipsky prior to isolation. Since the photoisomerization of komaroviquinone to komarovispirone is rapid, if it occurred within the semi-shrub, then komaroviquinone should not have been isolated and komarovispirone would have been the major component isolated.