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Volumn 62, Issue 49, 2006, Pages 11450-11459

Amino acid-peptide-catalyzed enantioselective Morita-Baylis-Hillman reactions

Author keywords

[No Author keywords available]

Indexed keywords

AMINO ACID; KETONE; PEPTIDE; PROLINE;

EID: 33750437400     PISSN: 00404020     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tet.2006.05.005     Document Type: Article
Times cited : (63)

References (75)
  • 16
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    • For recent ketone-based enantioselective MBH reactions, see:
  • 26
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    • The Shi laboratory reported imidazole in the presence of proline as a co-catalyst (30 mol % each), which afforded enhanced reactivity in the MVK-MBH reaction. Yields of up to 90% were obtained for a variety of activated aldehydes. See:
    • The Shi laboratory reported imidazole in the presence of proline as a co-catalyst (30 mol % each), which afforded enhanced reactivity in the MVK-MBH reaction. Yields of up to 90% were obtained for a variety of activated aldehydes. See:. Shi M., Jiang J.-K., and Li C.-Q. Tetrahedron Lett. 43 (2002) 127-130
    • (2002) Tetrahedron Lett. , vol.43 , pp. 127-130
    • Shi, M.1    Jiang, J.-K.2    Li, C.-Q.3
  • 27
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    • Proline has been shown to be an efficient and selective catalyst for a number of transformations. For reviews covering this chemistry, see the following and references therein:
  • 29
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    • List B. Synlett (2001) 1675-1686
    • (2001) Synlett , pp. 1675-1686
    • List, B.1
  • 30
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    • List B. Tetrahedron 58 (2002) 5573-5590
    • (2002) Tetrahedron , vol.58 , pp. 5573-5590
    • List, B.1
  • 34
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    • The sequences for the unbiased peptide libraries were defined randomly by assigning a numerical descriptor (1-16) to each of 16 unique amino acids. These 16 labels were then randomized at 'www.randomizer.org' using a random sequence generator. The random pentapeptide libraries were initially synthesized for the kinetic resolution of tertiary alcohols and previously characterized by MS and reported elsewhere. See:
    • The sequences for the unbiased peptide libraries were defined randomly by assigning a numerical descriptor (1-16) to each of 16 unique amino acids. These 16 labels were then randomized at 'www.randomizer.org' using a random sequence generator. The random pentapeptide libraries were initially synthesized for the kinetic resolution of tertiary alcohols and previously characterized by MS and reported elsewhere. See:. Jarvo E.R., Evans C.A., Copeland G.T., and Miller S.J. J. Org. Chem. 66 (2001) 5522-5527
    • (2001) J. Org. Chem. , vol.66 , pp. 5522-5527
    • Jarvo, E.R.1    Evans, C.A.2    Copeland, G.T.3    Miller, S.J.4
  • 35
    • 33750449255 scopus 로고    scopus 로고
    • note
    • 3. The reactions were stirred at room temperature for 16 h followed by purification and screening for enantioselectivity by chiral HPLC.
  • 36
    • 33750468246 scopus 로고    scopus 로고
    • For studies that describe the conformational biasing prowess of Aib, see:
  • 37
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    • Ref. 13
  • 39
    • 33750448567 scopus 로고    scopus 로고
    • note
    • Because peptides 3 and 4 exhibited identical sequences at the positions i through i+2, we chose these peptides to begin SAR studies.
  • 40
    • 33750428138 scopus 로고    scopus 로고
    • note
    • 3) as solvent provided enhanced enantioselectivity.
  • 41
    • 33750465771 scopus 로고    scopus 로고
    • For reviews on combinatorial catalyst screening, see the following papers and references therein:
  • 47
    • 33750428874 scopus 로고    scopus 로고
    • note
    • Previous studies in our laboratory have demonstrated that focused libraries based on initial hit peptide structures can lead to more selective peptide sequences. See Ref. 2b.
  • 48
    • 33750449942 scopus 로고    scopus 로고
    • note
    • The synthesis of each peptide sequence was confirmed by MS analysis and crude peptides were then screened in the MBH reaction.
  • 49
    • 33750459628 scopus 로고    scopus 로고
    • note
    • We recognize that this decision assumes the peptide sequence thus far is optimal at each amino acid position, and therefore, this decision does not take into account cooperativity of the different amino acids.
  • 50
    • 33750432417 scopus 로고    scopus 로고
    • note
    • We also synthesized peptides of shorter length, catalysts 12-15, to determine if the length-selectivity trend would be apparent with smaller peptides. Shorter peptide lengths such as dipeptide 13, tripeptide 14, and tetrapeptide 15 did appear to follow this trend with the limited number of cases examined.
  • 51
    • 33750474004 scopus 로고    scopus 로고
    • note
    • A brief study of the peptide/proline ratio revealed that 1:1 stoichiometry is optimal in the cases we explored.
  • 52
    • 33750429882 scopus 로고    scopus 로고
    • note
    • 3 yielded similar selectivities of 78% ee in the MBH reaction of 2-nitrobenzaldehyde with peptide 18.
  • 53
    • 33750461192 scopus 로고    scopus 로고
    • note
    • 3 (2:1) solvent mixtures.
  • 54
    • 17844379719 scopus 로고    scopus 로고
    • For a review addressing the reversal of stereochemistry in enantioselective reactions, see:
    • For a review addressing the reversal of stereochemistry in enantioselective reactions, see:. Sibi M.P., and Liu M. Curr. Org. Chem. 5 (2001) 719-755
    • (2001) Curr. Org. Chem. , vol.5 , pp. 719-755
    • Sibi, M.P.1    Liu, M.2
  • 55
    • 0021775497 scopus 로고
    • We note that the nonadditivity of the single components of the co-catalysts system suggests that the cooperativity among chiral species is nonclassical in the sense of double stereodifferentiation. See:
    • We note that the nonadditivity of the single components of the co-catalysts system suggests that the cooperativity among chiral species is nonclassical in the sense of double stereodifferentiation. See:. Masamune S., Choy W., Petersen J.S., and Sita L.R. Angew. Chem., Int. Ed. Engl. 97 (1985) 1-31
    • (1985) Angew. Chem., Int. Ed. Engl. , vol.97 , pp. 1-31
    • Masamune, S.1    Choy, W.2    Petersen, J.S.3    Sita, L.R.4
  • 56
    • 33750431304 scopus 로고    scopus 로고
    • N-Methyl amino acids were synthesized according to the following procedure. See:
  • 59
    • 37049079179 scopus 로고
    • The Li and Na-salts were prepared by mixing proline with either LiOH or NaOH in methanol for 10 min as reported in:
    • The Li and Na-salts were prepared by mixing proline with either LiOH or NaOH in methanol for 10 min as reported in:. Yamaguchi M., Yokota N., and Minami T. J. Chem. Soc., Chem. Commun. (1991) 1088-1089
    • (1991) J. Chem. Soc., Chem. Commun. , pp. 1088-1089
    • Yamaguchi, M.1    Yokota, N.2    Minami, T.3
  • 60
    • 33750473288 scopus 로고    scopus 로고
    • For the preparation of 5-substituted proline derivatives, see:
  • 63
    • 33750452227 scopus 로고    scopus 로고
    • note
    • Proline has been shown to serve as a catalyst for a variety of catalytic asymmetric reactions. See Ref. 12.
  • 68
    • 33750444861 scopus 로고    scopus 로고
    • For some important recent work on the mechanism of acrylate-based variants of the MBH reaction, see:
  • 72
  • 73
    • 33750460174 scopus 로고    scopus 로고
    • Chloroform was washed with concentrated sulfuric acid (5×5 mL) followed by washing with water (5×5 mL), dried over potassium carbonate, and distilled under nitrogen. See: Armarego, W. L. F.; Perrin, D. D. Purification of Laboratory Chemicals, 4th ed.; Butterworth and Heinemann: Oxford, 1997; p 143.
  • 74
    • 33750472257 scopus 로고    scopus 로고
    • note
    • 1H NMR.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.