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Tetrahedron Letters
Volumn 43, Issue 31, 2002, Pages 5491-5494
Synthesis of the C(1)-C(16) fragment of bryostatins
Author keywords

[No Author keywords available]
Indexed keywords

ACETAL DERIVATIVE; ALLYL COMPOUND; BRYOSTATIN; KETONE DERIVATIVE; SILANE DERIVATIVE;
EID: 0037194198     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(02)01054-7     Document Type: Article
Times cited : (35)
References (18)
  • 10
    • 0005770360 scopus 로고    scopus 로고
    • The geometries of all the allylsilanes were confirmed by NOE studies.
  • 14
    • 0005678352 scopus 로고    scopus 로고
    • The cis- and trans-configurations of 15 and 17 were established by NOE studies.
  • 15
    • 0005761019 scopus 로고    scopus 로고
    • The benzyl ether was chosen because of its stability to the acidic conditions used in the thermodynamic cyclisation reactions. Partial deprotection was observed during the cyclisation if, for example, p-methoxybenzyl protection was used.
  • 16
    • 0005761020 scopus 로고    scopus 로고
    • The acetate 26 has been converted into the fully protected polyol i which also corresponds to the C(1)-C(17) fragment of a bryostatin, albeit lacking the exocyclic methoxycarbonylmethylene group, by cleavage of the exocyclic methylene group, protection of the ketone so formed and reduction/protection of the 2′-ketone, followed by addition of the C(1)-C(4) fragment via a hydroboration/oxidation, aldol condensation, reduction and acetalisation sequence.
  • 18
    • 0005761173 scopus 로고    scopus 로고
    • This aldol reaction of ketone 34 was complicated by competing deprotonation of the ketone at the α-methylene group leading to the formation of regioisomers as minor products (ca. 20%). This could be avoided by using the analogous 4-tert-butyldiphenylsilyloxybutan-2-one which gave a better, 76%, yield of aldol product, but this led to the formation of the tetra-acetate ii on cyclisation followed by acetylation since the tert-butyldiphenylsilyloxy group was not stable under the acidic cyclisation conditions. The chemistry of ii has not been studied further at present.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.