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Volumn 61, Issue 11, 2005, Pages 2803-2814

Hydrogen atom transfer methodology for the synthesis of C-22, C-23, and C-25 stereoisomers of cephalostatin north 1 side chain from spirostan sapogenins

Author keywords

Alkoxyl radical; Cephalostatin; Hydrogen abstraction; Radical reaction; Spirostan sapogenin; Steroid

Indexed keywords

1,6 DIOXASPIRO[4.4]NONANE; 1,6 DIOXASPIRO[4.5]DECANE; CEPHALOSTATIN; DECANE; UNCLASSIFIED DRUG;

EID: 14244268192     PISSN: 00404020     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tet.2005.01.077     Document Type: Article
Times cited : (28)

References (81)
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    • See for example: pairs of ritterazines A/D, B/F (Ref. 2b) and N/O, P/Q, R/S and W/X (Ref. 2c).
    • See for example: pairs of ritterazines A/D, B/F (Ref. 2b) and N/O, P/Q, R/S and W/X (Ref. 2c).
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    • For studies of the influence of polar factors on intermolecular hydrogen abstraction reactions see: (a) A.L.J. Beckwith, and A.A. Zavitsas J. Am. Chem. Soc. 117 1995 607 614
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    • Although we have no experimental support for this reasoning, it is strongly supported by previous results on related models. For examples of the influence of the polarity of the substituents on the 1,5-hydrogen atom tranfer reaction compared with competing β-fragmentation of alkoxyl radicals, see: (a) P.R. Allen, M.A. Brimble, and F.A. Farès J. Chem. Soc., Perkin Trans. 1 1998 2403 2411
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    • note
    • 2).
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    • note
    • Crystallographic data (excluding structure factors) for the structures 18, 23, 29, and 34 in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication numbers CCDC-176076, CCDC-176077, CCDC-243668, CCDC-243669 respectively. Copies of the data can be obtained, free of charge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: +44 (0) 1223-336033 or e-mail: deposit@ccdc.cam.ac.uk ].
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    • No compounds of the 1,6-dioxaspiro[4.5]decane type belonging to the (22S)-spirostan, (20R,22R)-spirostan (cyclopseudoiso), or (20R,22S)-spirostan (cyclopseudoneo) series of spirostan sapogenins, which are theoretically possible through an oxocarbenium ion via an intermediate of furost-20(22)-en sapogenin, were detected during these acid-catalyzed experiments. (a) L.F. Fieser, and M. Fieser Steroids 1959 Reinhold Publishing Corp New York Chapter 19, pp 810-846
    • (1959) Steroids
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    • note
    • 24b=90.6°).
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    • Data were taken from the X-ray analysis of (22S,23R,25S)-3β, 12β-diacetoxy-22,25-epoxy-5α-furostan-23,26-diol. J.U. Jeong, and P.L. Fuchs J. Am. Chem. Soc. 116 1994 773 774
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    • (Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK)
    • j (J=0-4) were obtained from the X-ray cif files using Mercury v. 1.2.1 (Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK) (http://www.ccdc.cam.ac.uk/mercury/).
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    • Shortly before submitting our preliminary communication (Ref. 9) we became aware of the studies by Prof. P.L. Fuchs in the ASAP section of Organic Letters (Refs. 5g, 19b, see also Ref. 5c) where IHA reactions are used to prepare related dioxaspiro compounds.
    • ASAP Section of Organic Letters
    • Fuchs, P.L.1


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.