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Volumn 13, Issue 5, 2011, Pages 1222-1225

A short asymmetric route to the bromophycolide A and D skeleton

Author keywords

[No Author keywords available]

Indexed keywords

BROMINATED HYDROCARBON; BROMOPHYCOLIDE A; BROMOPHYCOLIDE D; DITERPENE;

EID: 79952128803     PISSN: 15237060     EISSN: 15237052     Source Type: Journal    
DOI: 10.1021/ol200099n     Document Type: Article
Times cited : (20)

References (44)
  • 5
    • 77950341605 scopus 로고    scopus 로고
    • Though alkenes 1, 2, and 3 are likely to form cyclic bromonium ions at similar rates, bromonium transfer between alkenes is likely to be rapidly reversible, so that the reaction outcome is determined by the relative rates at which these various species react further:;;,-1233
    • Though alkenes 1, 2, and 3 are likely to form cyclic bromonium ions at similar rates, bromonium transfer between alkenes is likely to be rapidly reversible, so that the reaction outcome is determined by the relative rates at which these various species react further: Denmark, S. E.; Burk, M. T.; Hoover, A. J. J. Am. Chem. Soc. 2010, 132, 1232-1233
    • (2010) J. Am. Chem. Soc. , vol.132 , pp. 1232
    • Denmark, S.E.1    Burk, M.T.2    Hoover, A.J.3
  • 11
    • 0028789811 scopus 로고
    • Ligand 9: A related ligand:; Org. Lett. 2001, 3, 3211-3214
    • Ligand 9: Corey, E. J.; Noe, M. C.; Lin, S. Tetrahedron Lett. 1995, 36, 8741-8744 A related ligand: Corey, E. J.; Zhang, J. Org. Lett. 2001, 3, 3211-3214
    • (1995) Tetrahedron Lett. , vol.36 , pp. 8741-8744
    • Corey, E.J.1    Noe, M.C.2    Lin, S.3    Corey, E.J.4    Zhang, J.5
  • 12
    • 79952147945 scopus 로고    scopus 로고
    • Determined by Mosher ester analysis (see Supporting Information).
    • Determined by Mosher ester analysis (see Supporting Information).
  • 15
    • 79952177394 scopus 로고    scopus 로고
    • The bromohydrin derived from ester 11 could not be converted to acid 13, due to multiple side reactions under a variety of basic and Lewis acidic ester cleavage conditions.
    • The bromohydrin derived from ester 11 could not be converted to acid 13, due to multiple side reactions under a variety of basic and Lewis acidic ester cleavage conditions.
  • 18
    • 79952169871 scopus 로고    scopus 로고
    • Slow addition of substrate (48 h) and elevated temperature (50 °C) were critical in order to ensure that the seco acid was consumed faster than it was added, preventing diolide formation. These conditions were robust on a scale of several hundered milligrams.
    • Slow addition of substrate (48 h) and elevated temperature (50 °C) were critical in order to ensure that the seco acid was consumed faster than it was added, preventing diolide formation. These conditions were robust on a scale of several hundered milligrams.
  • 19
    • 79952135371 scopus 로고    scopus 로고
    • See Supporting Information.
    • See Supporting Information.
  • 20
    • 79952149886 scopus 로고    scopus 로고
    • Other reagents employed included NBS, NBS/acids, NBS/phosphines, and TBCHD (2,4,4,6-tetrabromocyclohexadienone).
    • Other reagents employed included NBS, NBS/acids, NBS/phosphines, and TBCHD (2,4,4,6-tetrabromocyclohexadienone).
  • 23
    • 79952127995 scopus 로고    scopus 로고
    • We presume this highly polar solvent mixture to be helpful in prolonging the life of the cationic intermediate 19 long enough for the slow cyclization step to occur. Potentially, this solvent may also promote a compact and more cyclization-prone conformation of 19 via hydrophobic effects.
    • We presume this highly polar solvent mixture to be helpful in prolonging the life of the cationic intermediate 19 long enough for the slow cyclization step to occur. Potentially, this solvent may also promote a compact and more cyclization-prone conformation of 19 via hydrophobic effects.
  • 24
    • 84982207554 scopus 로고
    • a of the conjugate acid of dimethylsulfide is -5 (see:,-403), making it far less basic than leaving groups derived from other bromonium sources. A reviewer has suggested that BDSB may generally give cleaner reactions because its high reactivity allows the use of lower temperatures
    • a of the conjugate acid of dimethylsulfide is -5 (see: Arnett, E. M. Prog. Phys. Org. Chem. 1963, 1, 223-403), making it far less basic than leaving groups derived from other bromonium sources. A reviewer has suggested that BDSB may generally give cleaner reactions because its high reactivity allows the use of lower temperatures
    • (1963) Prog. Phys. Org. Chem. , vol.1 , pp. 223
    • Arnett, E.M.1
  • 42
    • 79952160200 scopus 로고    scopus 로고
    • See Supporting Information for a full discussion of NMR data.
    • See Supporting Information for a full discussion of NMR data.
  • 43
    • 79952128314 scopus 로고    scopus 로고
    • note
    • To claim selectivity, we must claim the absence of significant regio-and diastereomers of 7 and 15. LC of the crude product mixture shows no significant quantities of additional cyclization products. The identified products comprise >80% of the crude LC; the only unidentified product present at greater than 3% abundance is quickly solvolyzed in methanol and is presumably a diastereo-or regioisomer of allylic bromide 16.
  • 44
    • 79952164104 scopus 로고    scopus 로고
    • note
    • 11-bis-epi -Bromophycolide S.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.