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Volumn , Issue 15, 2009, Pages 2509-2516

Pyrrolidine-based organocatalysts for enantioselective Michael addition of cyclohexanone to trans-β-nitrostyrene

Author keywords

Addition reactions; Asymmetric catalysis; Bifunctional catalysis; Michael additions; Nitroolefin

Indexed keywords

ASYMMETRIC CATALYSIS; ASYMMETRIC INDUCTION; BI-FUNCTIONAL CATALYSTS; BIFUNCTIONAL CATALYSIS; CYCLOHEXANONES; DIASTEREOSELECTION; ENANTIOSELECTION; ENANTIOSELECTIVE MICHAEL ADDITION; MICHAEL ADDITIONS; NITROOLEFIN; NITROSTYRENE; ORGANOCATALYSTS; PYRROLIDINES; REACTION TIME;

EID: 69749118719     PISSN: 00397881     EISSN: 1437210X     Source Type: Journal    
DOI: 10.1055/s-0029-1216885     Document Type: Article
Times cited : (16)

References (46)
  • 14
    • 34447103366 scopus 로고    scopus 로고
    • For recent examples of pyrrolidine-based diamine catalysts, see
    • For recent examples of pyrrolidine-based diamine catalysts, see: (a) Chen, H. B.; Wang, Y.; Wei, S. Y.; Sun, J. Tetrahedron: Asymmetry 2007, 18, 1308.
    • (2007) Tetrahedron: Asymmetry , vol.18 , pp. 1308
    • Chen, H.B.1    Wang, Y.2    Wei, S.Y.3    Sun, J.4
  • 21
    • 33746643770 scopus 로고    scopus 로고
    • For recent examples of pyrrolidine-based thiourea-functionalised catalysts, see
    • For recent examples of pyrrolidine-based thiourea-functionalised catalysts, see: (a) Cao, C. L.; Ye, M. C.; Sun, X. L.; Tang, Y. Org. Lett. 2006, 8, 2901.
    • (2006) Org. Lett. , vol.8 , pp. 2901
    • Cao, C.L.1    Ye, M.C.2    Sun, X.L.3    Tang, Y.4
  • 36
    • 69749113134 scopus 로고    scopus 로고
    • note
    • We also prepared pyrrolidines with 2-carboxamide- or 2-methylacetamide- tethered thiourea and thiouronium functionality. Attempted catalysis of the conjugate addition of cyclohexanone to trans-b-nitrostyrene typically resulted in a syn/anti diastereomeric product ratio of >91:9 with carboxamide-tethered catalysts, comparable to that seen with monofunctional catalysis by (2S)-N-benzylpyrrolidine-2-carboxamide. However, poor syn enantioselectivity (<30% ee) resulted and all methylacetamide-tethered examples demonstrated little or no catalytic activity. Similar amide-linked, amine-thiourea catalysts were also reported to give only the racemic product of ketone addition to nitroolefins during the course of our study (ref. 7e), presumably as a result of intramolecular hydrogen bonding between thiourea/uronium functionality and the tethering amide.
  • 40
    • 69749093950 scopus 로고    scopus 로고
    • note
    • To our knowledge, comparable rates of catalysis for the Michael addition of ketones to nitroalkenes only by diamines have been reported; see references 4e, 6a, and 6b.
  • 44
    • 69749093709 scopus 로고    scopus 로고
    • note
    • 2O at r.t. Typically syn/anti diastereomeric ratios of 1:1 or 2:1 resulted with catalysts 4, 6, 7, 10, 12, or 14; major diastereoisomer ee (%) ranged between 8-77%.
  • 45
    • 69749103158 scopus 로고    scopus 로고
    • note
    • 3, 24°C), see ref. 22.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.