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Volumn 39, Issue 19, 1998, Pages 2903-2906

Synthesis of the C1-C9 core of bengazole A: Harnessing the ambident nucleophilicity of 2-lithiooxazole

Author keywords

Antifungals; Natural products; Oxazoles; Sponges

Indexed keywords

2 LITHIOOXAZOLE; AMPHOTERICIN B; BENGAZOLE A; FLUCONAZOLE; NATURAL PRODUCT; OXAZOLE DERIVATIVE; UNCLASSIFIED DRUG;

EID: 0032492936     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(98)00494-8     Document Type: Article
Times cited : (28)

References (31)
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    • (g) Knight, D.W.; Pattenden, G.; Rippon, D.E. Synlett, 1990, 1, 36. Useful alternatives to the serine amide motiff can be seen in the 'aziridine approach', eg.
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    • Knight, D.W.1    Pattenden, G.2    Rippon, D.E.3
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    • (4) Hodges, J. C.; Patt, W. C.; Connolly, C. J. J. Org. Chem. 1991, 56, 449-452 and citations, within. Coupling of 4 with a variety of aldehydes occurs exclusively at C-4 in 20-65% yield.
    • (1991) J. Org. Chem. , vol.56 , pp. 449-452
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    • note
    • 13C NMR spectra, and elemental analysis or HRMS.
  • 23
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    • note
    • 4HCOO-MeOH) was sluggish (>4 days) and gave mixtures with incomplete reaction or over-reducted alditol 9. Pretreating the substrate to remove trace sulfur impurities (Ra-Ni, EtOH, reflux) was only partially successful in improving the yield of 8.
  • 25
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    • note
    • (11) The addition of phenyllithium to ent-8 proceeded in 86% yield and 1:2.4 diastereoselectivity in favor of the desired 6R epimer (bengazole numbering). See Ref. 1b.
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    • note
    • 5Si requires 372.2206.
  • 27
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    • (13) The modest yield appears to be due, in part, to lower reactivity of 2-lithiooxazole compared to PhLi (see note 11) and competing enolization of 3 and β-elimination. Addition of 1.5 equiv of 2-lithiooxazole to 3 gave only ∼ 7% yield of 2. We are addressing this problem by modifying the preformed 2-lithiooxazole (enolate) prior to addition of 3, however other reaction pathways may be operative, see Iddon, B. Heterocydes 1994, 37, 1321-1346.
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    • (15) Vedejs, E.; Monahan, S. D. J. Org. Chem. 1996, 61, 5192-5193. The exception is oxazole-4-carboxylate derivatives which deprotonate and add electrophiles at C-5, exclusively.
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    • Vedejs, E.1    Monahan, S.D.2


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.