A novel strategy for the enantioselective synthesis of the steroidal framework using cascade ring expansion reactions of small ring systems- asymmetric total synthesis of (+)-equilenin

Tetrahedron Letters

Volumn 40, Issue 5, 1999, Pages 907-910

  Nemoto, Hideo ^a   Yoshida, Masahiro ^a   Fukumoto, Keiichiro ^a   Ihara, Masataka ^a  

^a TOHOKU UNIVERSITY   (Japan)

Author keywords

Asymmetric synthesis; Rearrangement; Stereocontrol; Steroids and sterols

Indexed keywords

EQUILIN;

ARTICLE; CONFORMATIONAL TRANSITION; DRUG CONFORMATION; DRUG SYNTHESIS; ENANTIOMER; STEREOCHEMISTRY; STRUCTURE ANALYSIS;

EID: 0033613808     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(98)02479-4     Document Type: Article

References (21)

1. For reviews, see (a) Pappo, R. Annu. Rep. Med. Chem. 1967, 307-316.
2. (b) Akhrem, A. A.; Titov, Y. A.; Total Steroid Synthesis, Plenum Press, New York, 1970.
3. (c) Steroids, Vol. 8; Johns, W. F., Eds.; M. T. P. International Review of Science, Organic Chemistry, Butterworths, London, 1973.
4. (d) The Total Synthesis of Natural Products Vol. 2; ApSimon, J. W. Eds.; Wiley-Interscience, New York, 1973.
5. (e) Johnson, W. S. Angew. Chem. Int. Ed. Engl. 1976, 15, 9-16.
6. (f) Kametani, T.; Nemoto, H. Heterocycles 1978, 10, 349-390.
7. (g) Kametani, T.; Nemoto, H. Tetrahedron 1981, 37, 3-16.
8. (h) Nemoto, H.; Fukumoto, K. Tetrahedron 1998, 54, 5425-5464.
9. Nemoto, H.; Miyata, J.; Yoshida, M.; Raku, N.; Fukumoto, K. J. Org. Chem. 1997, 62, 7850-7857.
10. (a) Zhang, W.; Jacobsen, E. N. J. Org. Chem. 1991, 56, 2296-2298.
11. (b) Jacobsen, E. N.; Zhang, W.; Muci, A. R.; Ecker, J. R.; Deng, L. J. Am. Chem. Soc. 1991, 113, 7063-7064.
12. Our recent work on the syntheses of the chiral cyclobutanones by other methods: Nemoto, H.; Fukumoto, K. Synlett 1997, 863-875 and references cited therein.
13. 6 was readily available from-methoxy-1-tetralone in 2 steps: Bilger, C.; Demerseman, P.; Royer, R. Eur. J. Med. Chem. 1987, 22, 363-365.
14. Scott, W. J.; Stille, J. K. J. Am. Chem. Soc. 1986, 108, 3033-3040.
15. Stafford, J. A.; McMurry, J. E. Tetrahedron Lett. 1988, 29, 2531-2534.
16. +), found 252.1150. Enantiomeric excess was determined by HPLC analysis (Chiralcel OA column, 10% isopropanol-hexane, 0.5 mL/min, λ=254 nm, 23°C, retension times 21.1min (R), 26.2min(S)). Absolute configuration was determined by Kusumi's procedure using MTPA esters 17, which were prepared by reduction of the cyclobutanone 4, followed by esterification of the major isomer 16 with (R) or (S)-MTPA (see below): Ohtani, I.; Kusumi, T.; Kashman, Y.; Kakisawa, H. J. Am. Chem. Soc. 1991, 113, 4092-4096.
17. Imamoto, T.; Takiyama, N.; Nakamura, K.; Hatajima, T.; Kamiya, Y. J. Am. Chem. Soc. 1989, 111, 4392-4398.
18. + complex wasn't effectively produced for less acidity of AcOH than that of HCl generated in situ resulted to preserve the isomerizasion.
19. +), found 294.1246.
20. Birch, A. J.; Subba Rao, G. S. R. Tetrahedron Lett. 1967, 23, 2763-2767.
21. 1H-NMR spectrum was in complete agreement with that of an authentic sample.