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Volumn 11, Issue 6, 2007, Pages 951-955

Syntheses of 4,5-disubstituted oxazoles via regioselective C-4 bromination

Author keywords

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Indexed keywords


EID: 37049019663     PISSN: 10836160     EISSN: None     Source Type: Journal    
DOI: 10.1021/op700176n     Document Type: Article
Times cited : (32)

References (46)
  • 1
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    • (j) Revesz, L.; Schlapbach, A. PCT Int. Appl. WO 2000063204,2000; Chem. Abstr. 133:321897.
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    • Chem. Abstr. 132:217886.
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    • McClure, K. F.; Letavic, M. A.; Kalgutkar, A. S.; Gabel, C. A.; Audoly, L.; Barberia, J. T.; Braganza, J. F.; Carter, D.; Thomas, J.; Carty, T. J.; Cortina, S, R.; Dombroski, M. A.; Donahue, K. M.; Elliott, N. C.; Gibbons, C. P.; Jordan, C. K.; Kuperman, A. V.; Labasi, J. M.; LaLiberte, R. E.; McCoy, J. M.; Naiman, B. M.; Nelson, K. L.; Nguyen, H. T.; Peese, K. M.; Sweeney, F. J.; Taylor, T. J.; Trebino, C. E.; Abramov, Y. A.; Laird, E. R.; Volberg, W. A.; Zhou, J.; Bach, J.; Lombardo, F. Bioorg. Med. Chem. Lett. 2006, 16, 4339-4344.
    • (b) McClure, K. F.; Letavic, M. A.; Kalgutkar, A. S.; Gabel, C. A.; Audoly, L.; Barberia, J. T.; Braganza, J. F.; Carter, D.; Thomas, J.; Carty, T. J.; Cortina, S, R.; Dombroski, M. A.; Donahue, K. M.; Elliott, N. C.; Gibbons, C. P.; Jordan, C. K.; Kuperman, A. V.; Labasi, J. M.; LaLiberte, R. E.; McCoy, J. M.; Naiman, B. M.; Nelson, K. L.; Nguyen, H. T.; Peese, K. M.; Sweeney, F. J.; Taylor, T. J.; Trebino, C. E.; Abramov, Y. A.; Laird, E. R.; Volberg, W. A.; Zhou, J.; Bach, J.; Lombardo, F. Bioorg. Med. Chem. Lett. 2006, 16, 4339-4344.
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    • Preparation and handling of 4-fluorophenyl and 3,4-difluorophenyl tosylmethylisocyanides were considerably less problematic. See ref 3b
    • Preparation and handling of 4-fluorophenyl and 3,4-difluorophenyl tosylmethylisocyanides were considerably less problematic. See ref 3b.
  • 29
  • 33
    • 37049008491 scopus 로고    scopus 로고
    • Contaminated with <2% of the 2-bromoxazole 9 and <0.2% of the 2,4-dibromo 10.
    • Contaminated with <2% of the 2-bromoxazole 9 and <0.2% of the 2,4-dibromo 10.
  • 38
    • 37049013328 scopus 로고    scopus 로고
    • Although the freezing point of DMF is -61 °C, the reaction mixture had a freezing point of < -70 °C
    • Although the freezing point of DMF is -61 °C, the reaction mixture had a freezing point of < -70 °C.
  • 39
    • 37049013950 scopus 로고    scopus 로고
    • Quenching the reaction at -15 °C with NBS led to a ca. 2/1 ratio of regioisomers, favoring the C-4 product. NBS was added as a solution in DMF (2.7 mL/g of NBS) at room temperature. Pre-cooling of the NBS solution would be desirable, but it reduced the solubility significantly. More studies are needed to determine if the anion quench can be adapted in a flow reactor under non-cryogenic conditions.
    • Quenching the reaction at -15 °C with NBS led to a ca. 2/1 ratio of regioisomers, favoring the C-4 product. NBS was added as a solution in DMF (2.7 mL/g of NBS) at room temperature. Pre-cooling of the NBS solution would be desirable, but it reduced the solubility significantly. More studies are needed to determine if the anion quench can be adapted in a flow reactor under non-cryogenic conditions.
  • 40
    • 37049005595 scopus 로고    scopus 로고
    • A trace amount (<1%) of the dibromide 10 was observed in the reaction but was purged during the isolation of 8.
    • A trace amount (<1%) of the dibromide 10 was observed in the reaction but was purged during the isolation of 8.
  • 41
    • 20244364689 scopus 로고    scopus 로고
    • Some examples of palladium purging methods: Welch, C. J.; Albaneze-Walker, J.; Leonard, W. R.; Biba, M.; DaSilva, J.; Henderson, D.; Laing, B.; Mathre, D. J.; Spencer, S.; Bu, X.; Wang, T. Org. Process Res. Dev. 2005, 9, 198-205.
    • (a) Some examples of palladium purging methods: Welch, C. J.; Albaneze-Walker, J.; Leonard, W. R.; Biba, M.; DaSilva, J.; Henderson, D.; Laing, B.; Mathre, D. J.; Spencer, S.; Bu, X.; Wang, T. Org. Process Res. Dev. 2005, 9, 198-205.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.