Electrocyclic ring closure of the enols of vinyl quinones. A 2H-chromene synthesis

Organic Letters

Volumn 3, Issue 24, 2001, Pages 3875-3878

  Parker, Kathlyn A ^a,b   Mindt, Thomas L ^a  

^a BROWN UNIVERSITY   (United States)

^b STONY BROOK UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

5,7 DIMETHOXY 2 METHYL 2H BENZOPYRAN; 5,7-DIMETHOXY-2-METHYL-2H-BENZOPYRAN; BENZOPYRAN DERIVATIVE; QUINONE DERIVATIVE;

ARTICLE; CHEMISTRY; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; SYNTHESIS;

BENZOPYRANS; MAGNETIC RESONANCE SPECTROSCOPY; QUINONES; SUPPORT, U.S. GOV'T, NON-P.H.S.; SUPPORT, U.S. GOV'T, P.H.S.;

EID: 0035969616     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol0167199     Document Type: Article

References (23)

1. Parker, K. A.; Georges, A. T. Org. Lett. 2000, 2 (4), 497-499 and references therein.
2. 3 oxidation of commercially available bromo hydroquinone according to McElvain, S. M.; Engelhardt, E. L. J. Am. Chem. Soc. 1944, 66, 1077-1080.
3. Collins, P. W.; Kramer, S. W.; Gasiecki, A. F.; Weier, R. M.; Jones, P. H.; Gullikson, G. W.; Bianchi, R. G. J. Med. Chem. 1987, 30, 193-197.
4. (a) Bowers, R. S.; Ohta, T.; Cleere, J. S.; Marsella, P. A. Science 1976, 193, 542-547.
5. (b) Ellis, G. P. Chromenes, Chromanones and Chromones. In Chemistry of Heterocyclic Compounds; John Wiley& Sons: New York, 1977; Vol. 31, pp 11-141.
6. (a) Chauder, B. A.; Lopes, C. C.; Lopes, R. S. C.; daSilva, A. J. M.; Snieckus, V. Synthesis 1998, 279-282 and references therein.
7. (b) Schweizer, E. E.; Minami, T.; Crouse, D. M. J. Org. Chem. 1971, 36 (26), 4028-4032.
8. (c) Zsindely, J.; Schmid, H. Helv. Chim. Acta 1968, 51 (7), 1510-1514.
9. The NMR spectra of this product are complex because of Sn coupling.
10. 3.
11. 3PO.
12. DMPU = 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone.
13. The intermediate was characterized by the absorbance spectrum of the reaction mixture which underwent a bathochromic shift from 333 nm (yellow) to 485 nm (dark red).
14. 13C NMR spectra of this solution are contained in the Supporting Information. These spectra support the conclusion that >80% of the quinone 3 had isomerized to enol 10.
15. (a) Kopanski, L.; Karbach, D.; Selbitschka, G.; Steglich, W. Liebigs Ann. Chem. 1987, 793-796.
16. (b) Iyer, M. R.; Baskaran, S.; Trivedi, G. K. J. Indian Chem. Soc. 1994, 71, 341-343.
17. (c) Bissada, S.; Lau, C. K.; Bernstein, M. A.; Dufresne, C. Can. J. Chem. 1994, 72, 1866-1869.
18. (d) See also refs 4b and 5.
19. Similar electrocyclic closures of dienones give mixtures of products; these do not benefit from the restoration of aromaticity obtained when the product is a benzopyran. See, for example: (a) Büchi, G.; Yang, N. C. J. Am. Chem. Soc. 1957, 79, 2318-2323.
20. (b) Ishii, K.; Mathies, P.; Nishio, T.; Wolf, H. R.; Frei, B.; Jeger, O. Helv. Chim. Acta 1984, 67, 1175-1183.
21. The preparation of these substrates is described in the Supporting Information. Quinones were prepared immediately before use, and all exeept substrates 3a and 3b were used as cis/trans mixtures. All new compounds were fully characterized. NMR spectra of quinones 11 and 14 show impurities which may be the corresponding enols. Quinones and benzopyran products bearing a hydrogen at the C-2 position were notably less stable than the C-2 (α to carbonyl) alkylated analogues.
22. Pari, K.; Rao, P. J.; Subrahmanyam, B.; Rasthogi, J. N.; Devakumar, C. Phytochemistry 1998, 49 (5), 1385-1388.
23. 1H NMR data for compounds 5, 13, and the reputed Ageratum juvenile hormone, see the Supporting Information.