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Volumn 6, Issue 19, 2000, Pages 3517-3521

Highly β-selective epoxidation of Δ5-unsaturated steroids catalyzed by ketones

Author keywords

Dioxiranes; Epoxidations; Ketones; Steroids; selectivity

Indexed keywords

ACETAL; ACETIC ACID DERIVATIVE; CARBONYL DERIVATIVE; EPOXIDE; ETHYLENE OXIDE DERIVATIVE; HYDROXYL GROUP; KETONE; STEROID;

EID: 0034596790     PISSN: 09476539     EISSN: None     Source Type: Journal    
DOI: 10.1002/1521-3765(20001002)6:19<3517::aid-chem3517>3.0.co;2-%23     Document Type: Article
Times cited : (26)

References (81)
  • 12
  • 13
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    • (Eds.: J. Fried, J. A. Edwards), Van Nostrand Reinhold, New York
    • b) G. J. Matthews, A. Hassner in Organic Reactions in Steroid Chemistry, Vol. 2 (Eds.: J. Fried, J. A. Edwards), Van Nostrand Reinhold, New York, 1972, p. 1;
    • (1972) Organic Reactions in Steroid Chemistry , vol.2 , pp. 1
    • Matthews, G.J.1    Hassner, A.2
  • 15
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    • USA 3676433, 1972
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  • 32
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    • It has been reported that epoxidation of epi-cholesterol with mCPBA provided a single 5α,6α-epoxide due to hydrogen-bonding. See: M. Mousseron-Canet, J.-C. Guilleux, Bull. Soc. Chim. Fr. 1966, 3853.
    • (1966) Bull. Soc. Chim. Fr. , pp. 3853
    • Mousseron-Canet, M.1    Guilleux, J.-C.2
  • 39
    • 0002552024 scopus 로고
    • (Ed.: A. L. Baumstark), JAI, Greenwich, CT
    • c) R. Curci in Advances in Oxygenated Processes, Vol. 2 (Ed.: A. L. Baumstark), JAI, Greenwich, CT, 1990, p. 1;
    • (1990) Advances in Oxygenated Processes , vol.2 , pp. 1
    • Curci, R.1
  • 51
    • 0346922811 scopus 로고    scopus 로고
    • 5-steroids by the sterically unhindered dioxiranes, the steric interactions in both β-TS and α-TS appear to be more or less the same; this results in low selectivities. See ref. [14b]
    • 5-steroids by the sterically unhindered dioxiranes, the steric interactions in both β-TS and α-TS appear to be more or less the same; this results in low selectivities. See ref. [14b].
  • 55
    • 32044456645 scopus 로고
    • 1H NMR spectra of the crude residues (δ = 3.00-3.15 for β-epoxides and δ 2.75-2.95 for α-epoxides). See: A. D. Cross, J. Am. Chem. Soc. 1962, 84, 3206.
    • (1962) J. Am. Chem. Soc. , vol.84 , pp. 3206
    • Cross, A.D.1
  • 56
    • 0346292734 scopus 로고    scopus 로고
    • Epoxidation of substrates 6-11 with mCPBA was also carried out for comparison (see Table 1); this gave α-epoxides as the major products
    • Epoxidation of substrates 6-11 with mCPBA was also carried out for comparison (see Table 1); this gave α-epoxides as the major products.
  • 57
    • 0347553900 scopus 로고    scopus 로고
    • 5-unsaturated steroids is not compatible with some metal-based oxidants in the epoxidation reactions. See references [9c,f]
    • 5-unsaturated steroids is not compatible with some metal-based oxidants in the epoxidation reactions. See references [9c,f].
  • 58
    • 0033525675 scopus 로고    scopus 로고
    • This is in agreement with our previous observation on diastereoselectivities exhibited by ketones 1-5 for epoxidation of cyclohexenes with allylic substituents. See: D. Yang, G.-S. Jiao, Y-C. Yip, M.-K. Wong, J. Org. Chem. 1999, 64, 1635.
    • (1999) J. Org. Chem. , vol.64 , pp. 1635
    • Yang, D.1    Jiao, G.-S.2    Yip, Y.-C.3    Wong, M.-K.4
  • 59
    • 0346922810 scopus 로고    scopus 로고
    • Since the 3α-substituents of steroids 13-21 are bulky enough to block the approach of dioxiranes from the α-face, the ratio of β/α epoxides is generally high (43:1 to > 99:1)
    • Since the 3α-substituents of steroids 13-21 are bulky enough to block the approach of dioxiranes from the α-face, the ratio of β/α epoxides is generally high (43:1 to > 99:1).
  • 60
    • 0346922809 scopus 로고    scopus 로고
    • For example, a multi-gram scale (10 mmol) epoxidation of substrate 19 catalyzed by ketone 3 (5 mol %) provided almost exclusively a single β-epoxide (β/α-epoxide ratio > 99:1) in 88% yield
    • For example, a multi-gram scale (10 mmol) epoxidation of substrate 19 catalyzed by ketone 3 (5 mol %) provided almost exclusively a single β-epoxide (β/α-epoxide ratio > 99:1) in 88% yield.
  • 67
    • 0023913120 scopus 로고
    • a) R. M. Evans, Science 1988, 240, 889;
    • (1988) Science , vol.240 , pp. 889
    • Evans, R.M.1


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.