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Volumn 44, Issue 39, 2005, Pages 6367-6370

Urea- and thiourea-substituted cinchona alkaloid derivatives as highly efficient bifunctional organocatalysts for the asymmetric addition of malonate to nitroalkenes: Inversion of configuration at C9 dramatically improves catalyst performance

Author keywords

Asymmetric catalysis; Cinchona alkaloids; Michael addition; Organocatalysis; Ureas

Indexed keywords

CATALYST ACTIVITY; OLEFINS;

EID: 26844450640     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200501721     Document Type: Article
Times cited : (658)

References (61)
  • 9
    • 4544234565 scopus 로고    scopus 로고
    • For a more recent study of this alkaloid-catalyzed reaction, see: P. McDaid, Y. Chen, L. Deng, Angew. Chem. 2002, 114, 348;
    • (2002) Angew. Chem. , vol.114 , pp. 348
    • McDaid, P.1    Chen, Y.2    Deng, L.3
  • 11
    • 0001462990 scopus 로고
    • For early examples of the use of chiral amines as nucleophilic organocatalysts, see: a) V. Prelog, H. Wilhelm, Helv. Chim. Acta 1954, 37, 1634;
    • (1954) Helv. Chim. Acta , vol.37 , pp. 1634
    • Prelog, V.1    Wilhelm, H.2
  • 24
    • 0000457126 scopus 로고
    • For early examples of the use of (thio)ureas as organocatalysts, see: a) D. P. Curran, L. H. Kuo, J. Org. Chem. 1994, 59, 3259;
    • (1994) J. Org. Chem. , vol.59 , pp. 3259
    • Curran, D.P.1    Kuo, L.H.2
  • 47
    • 15444366940 scopus 로고    scopus 로고
    • While this manuscript was being prepared, two reports detailing a similar strategy have appeared: a) for a report disclosing the synthesis of two C-1,2-didehydro cinchonidine/chinchonine-derived variants of 9-epi-DHQT (amongst others) which promoted the efficient addition to thiophenol to α-β-unsaturated imides with low selectivity (up to 17% ee), see: B.-J. Li, L. Jiang, M. Liu, Y.-C. Chen, L.-S. Ding, Y. Wu, Synlett, 2005, 603;
    • (2005) Synlett , pp. 603
    • Li, B.-J.1    Jiang, L.2    Liu, M.3    Chen, Y.-C.4    Ding, L.-S.5    Wu, Y.6
  • 48
    • 19544393388 scopus 로고    scopus 로고
    • b) 9-epi-DHQT and C-1,2-didehydro analogues have been prepared for use in the efficient enantioselective addition of nitromethane to chalcones, and a clear dependence of catalyst activity and selectivity on the relative stereochemistry at C8/C9 has been demonstrated: B. Vakulya, S. Varga, A. Csámpai, T. Soós, Org. Lett. 2005, 7, 1967.
    • (2005) Org. Lett. , vol.7 , pp. 1967
    • Vakulya, B.1    Varga, S.2    Csámpai, A.3    Soós, T.4
  • 52
    • 4143114533 scopus 로고    scopus 로고
    • For a recent review concerning the secondary-amine catalyzed addition of carbonyl compounds to nitroolefins, see: W. Notz, F. Tanaka, C. F. Barbas III, Acc. Chem. Res. 2004, 37, 580.
    • (2004) Acc. Chem. Res. , vol.37 , pp. 580
    • Notz, W.1    Tanaka, F.2    Barbas III, C.F.3
  • 56
    • 26844535219 scopus 로고    scopus 로고
    • note
    • The prefix "epi" usually refers only to inversion of configuration at a single stereocenter, that is, no functional-group interconversion is implied. The term is adopted in this case for convenient identification of the relative stereochemistry of the catalyst at C8/C9.
  • 57
    • 26844559937 scopus 로고    scopus 로고
    • note
    • To the best of our knowledge only Deng et al. (ref. [9]) have thus far successfully selectively converted this hindered substrate by using 20 mol % 6′-demethylated quinine.
  • 58
    • 26844437866 scopus 로고    scopus 로고
    • note
    • MM2 force-field energy-minimization calculations were carried out with CS Chem3D Std v.4.0 software. Conformers were minimized to a minimum RMS gradient of 0.02.
  • 59
    • 26844449295 scopus 로고    scopus 로고
    • note
    • [12e, 13b].
  • 61
    • 26844439838 scopus 로고    scopus 로고
    • note
    • This would account for the observed product stereochemistry, and the decrease in catalyst efficiency and selectivity associated with DHQU relative to 9-epi-DHQU. However, it is acknowledged that alternative rationales are possible, for example, reversal of binding selectivity relative to 9-epi-DHQU, etc. It is envisaged that ongoing structural studies will provide more detailed insight into the catalytic behaviour of these C9 diastereomers.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.