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Volumn 10, Issue 22, 1999, Pages 4427-4436

Free-radical cyclization of enantiomerically enriched 2-p-tolylthio derivatives of 2-allylcyclohexanones with Mn(III): Asymmetric synthesis of bridged bicyclic ketones and thiochroman-3-ones

Author keywords

[No Author keywords available]

Indexed keywords

CYCLOHEXANONE DERIVATIVE; KETONE; MANGANESE; THIOCHROMAN DERIVATIVE; THIOL DERIVATIVE;

EID: 0000299647     PISSN: 09574166     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0957-4166(99)00467-X     Document Type: Article
Times cited : (14)

References (52)
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  • 6
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    • (Shinetsu Chem. Ind. Co, Japan). Jpn. Kokai Tokkyo Koho JP Patent 0820588, 1996; CA 124, 328568, 1996
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    • Shimizu, T.1    Kano, T.2    Ogiwara, T.3    Kaneko, T.4    Nakajima, M.5    Kurihara, H.6
  • 18
    • 0343949752 scopus 로고    scopus 로고
    • note
    • Allylation in conditions reported in Ref. 6 (NaH, allyl bromide, DMF) are also satisfactory. Nevertheless, the instability of 3 in the conditions required to eliminate the solvent (DMF), previous to the cyclization step, made it advisable to use phase transfer conditions in dichloromethane. Under these conditions, compound 3 was obtained as a mixture of epimers at C-2, with des ranging between 80 and 86%.
  • 20
    • 0343077879 scopus 로고    scopus 로고
    • note
    • 4Cl, was unsuccessful.
  • 28
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    • Eur. Pat. Appl. EP Patent 678517, 1995; CA 124, 145901, 1996 and Jpn. Kokai Tokkyo Koho JP Patent 07258245, 1995; CA 124, 175832, 1996
    • Momota, J; Imura, T.; Kobayakawa, T. Eur. Pat. Appl. EP Patent 678517, 1995; CA 124, 145901, 1996 and Jpn. Kokai Tokkyo Koho JP Patent 07258245, 1995; CA 124, 175832, 1996.
    • Momota, J.1    Imura, T.2    Kobayakawa, T.3
  • 29
    • 0343513994 scopus 로고    scopus 로고
    • note
    • HPLC analysis was performed with: (a) Chiral column Chiralpak AS (25 cm×0.46 cm) eluting with a mixture of n-hexane:isopropanol (90:10), flow rate=1.0 mL/min, detection 220 nm, retention times: (-)-4, t=9.1 min; (+)-4, t=11.2 min; (-)-7, t=8.6 min; (+)-7, t=12.0 min.
  • 30
    • 0342643696 scopus 로고    scopus 로고
    • note
    • (b) Chiral column Chiralcel OD (25 cm×0.46 cm) eluting with a mixture of n-hexane/isopropanol (99:1), flow rate=1.0 mL/min, detection 254 nm, retention times: (-)-9, t=4.1 min; (+)-9, t=5.2 min; (-)-10, t=5.4 min; (+)-10, t=7.7 min.
  • 31
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    • note
    • (c) The ee of compound 5 could not be determined by chiral HPLC due to its insolubility in the eluting mixture.
  • 44
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    • note
    • The formation of the more congested five-membered exo radicals would be difficult because of the size of substituent at C-2.
  • 48
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    • Kochi, J. K., Ed.; Wiley: New York, chapter 11
    • (d) Kochi, J. K. In Free Radicals; Kochi, J. K., Ed.; Wiley: New York, 1973; chapter 11.
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    • (e) Kochi, J. K. Science 1967, 155, 415.
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    • Kochi, J.K.1
  • 50
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    • note
    • 1H NOESY spectrum of compound 9 is in full agreement with the axial arrangement of the sulfenyl group, showing connectivities between the proton H-2′ and the protons H-4ax and H-6ax and also between the proton H-8 and the protons H-3ax and H-3eq.
  • 52
    • 0342643694 scopus 로고    scopus 로고
    • note
    • 2) regardless of the conformational behavior of the substrates. Nevertheless, the fact that reaction time required for the complete evolution of compound 9 was larger (36 h) than that for 4 (8 h) suggests to us that this is not the case and other factors must be involved.


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