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Volumn 11, Issue 9, 2009, Pages 2003-2006

Mild and efficient DBU-catalyzed amidation of cyanoacetates

Author keywords

[No Author keywords available]

Indexed keywords

1,4 DIAZABICYCLO[2.2.2]OCTANE; 1,8 DIAZABICYCLO(5.4.0)UNDEC 7 ENE; 1,8-DIAZABICYCLO(5.4.0)UNDEC-7-ENE; ACETIC ACID DERIVATIVE; AMIDE; CP 690,550 10; CP-690,550-10; CYANOACETIC ACID; FUSED HETEROCYCLIC RINGS; IMMUNOSUPPRESSIVE AGENT; PIPERAZINE DERIVATIVE; PYRIMIDINE DERIVATIVE; PYRROLE DERIVATIVE;

EID: 65549151322     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol900435t     Document Type: Article
Times cited : (103)

References (31)
  • 3
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    • Tang, P. Org. Synth. 2005, 81, 262-272.
    • (2005) Org. Synth , vol.81 , pp. 262-272
    • Tang, P.1
  • 7
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    • Wilcox, G. E.; Koecher, C.; Vries, T.; Flanagan, M. E.; Munchhof, J. WO 2002/096909 A1, 2002.
    • Wilcox, G. E.; Koecher, C.; Vries, T.; Flanagan, M. E.; Munchhof, J. WO 2002/096909 A1, 2002.
  • 8
    • 66149142115 scopus 로고    scopus 로고
    • Rugged, S. G.; Hawkins, J. M.; Makowski, T. M.; Rutherford, J. L.; Urban, F. J. WO 2007/012953 A2, 2007.
    • Rugged, S. G.; Hawkins, J. M.; Makowski, T. M.; Rutherford, J. L.; Urban, F. J. WO 2007/012953 A2, 2007.
  • 9
    • 66149137127 scopus 로고    scopus 로고
    • In our experience, some activated forms of cyanoacetic acid, such as the acyl imidazole, decomposed readily to unidentifiable products
    • In our experience, some activated forms of cyanoacetic acid, such as the acyl imidazole, decomposed readily to unidentifiable products.
  • 15
    • 66149141310 scopus 로고    scopus 로고
    • Chew, W.; Papamichelakis, M.; Wang, Y. US App. 2005159446, 2005.
    • Chew, W.; Papamichelakis, M.; Wang, Y. US App. 2005159446, 2005.
  • 17
    • 66149103941 scopus 로고    scopus 로고
    • could be directly crystallized and isolated from this solvent
    • 1-Butanol was chosen because 1 could be directly crystallized and isolated from this solvent.
    • Butanol was chosen because , vol.1
  • 18
    • 66149088341 scopus 로고    scopus 로고
    • This screen was run in the Conjure Flow System, Accendo Corporation, Tucson, AZ
    • This screen was run in the Conjure Flow System, Accendo Corporation, Tucson, AZ.
  • 19
    • 66149085162 scopus 로고    scopus 로고
    • 1,5-Diazabicyclo[4.3.0]nonane (DBN) was subsequently compared to DBU in the reaction of 5 with 4 and gave virtually identical rate enhancement.
    • 1,5-Diazabicyclo[4.3.0]nonane (DBN) was subsequently compared to DBU in the reaction of 5 with 4 and gave virtually identical rate enhancement.
  • 20
    • 84868944668 scopus 로고    scopus 로고
    • The use of potassium tert-butoxide (t-BuOK) for the synthesis of cyanoacetamides under microwave conditions is known see ref 13, however, it led to low conversions in our case at 23 °C in 1-BuOH
    • The use of potassium tert-butoxide (t-BuOK) for the synthesis of cyanoacetamides under microwave conditions is known (see ref 13); however, it led to low conversions in our case at 23 °C in 1-BuOH.
  • 21
    • 66149108666 scopus 로고    scopus 로고
    • DBU accelerates the reaction of amine 5 and ethyl cyanoacetate (4) at lower loadings as well. The profiles for reactions run at 0.1-0.5 equiv of DBU are compared in the Supporting Information.
    • DBU accelerates the reaction of amine 5 and ethyl cyanoacetate (4) at lower loadings as well. The profiles for reactions run at 0.1-0.5 equiv of DBU are compared in the Supporting Information.
  • 23
    • 66149127978 scopus 로고    scopus 로고
    • A solvent screen on the conversion of 3 to 2 indicated that the DBU-promoted reaction worked well in most solvents slowing down only in polar aprotic solvents (NMP, DMSO). See the Supporting Information for further details.
    • A solvent screen on the conversion of 3 to 2 indicated that the DBU-promoted reaction worked well in most solvents slowing down only in polar aprotic solvents (NMP, DMSO). See the Supporting Information for further details.
  • 30
    • 0001578222 scopus 로고    scopus 로고
    • It is conceivable that the rate enhancement is due to the direct formation of a ketene from ethyl cyanoacetate and DBU. However, in the reaction of ethyl cyanoacetate with hydroxide, pre-equilibrium formation of the enolate is unproductive due to the poor leaving ability of ethoxide, and hydrolysis proceeds by a BAc2 mechanism rather than an E1cB (ketene) mechanism:Holmquist, B, Bruice, T. C. J. Am. Chem. Soc. 1969, 91, 3003-3009. Further work aimed at clarifying the mechanism is ongoing
    • It is conceivable that the rate enhancement is due to the direct formation of a ketene from ethyl cyanoacetate and DBU. However, in the reaction of ethyl cyanoacetate with hydroxide, pre-equilibrium formation of the enolate is unproductive due to the poor leaving ability of ethoxide, and hydrolysis proceeds by a BAc2 mechanism rather than an E1cB (ketene) mechanism:Holmquist, B.; Bruice, T. C. J. Am. Chem. Soc. 1969, 91, 3003-3009. Further work aimed at clarifying the mechanism is ongoing.
  • 31
    • 84868945646 scopus 로고    scopus 로고
    • Although the amidation of diethyl malonate with 5 was slow, the addition of DBU led to a 12-fold increase in reaction rate t1/2, 16 h with 0.5 equiv of DBU in 2-MeTHF at 40 °C, Significant rate enhancements have been observed in the amidation of acyl imidazoles as well. Larrivee- Aboussafy, C, Price, K. E, Hawkins, J. M, Vaidyanathan, R. Manuscript in preparation
    • 1/2 = 16 h with 0.5 equiv of DBU in 2-MeTHF at 40 °C). Significant rate enhancements have been observed in the amidation of acyl imidazoles as well. Larrivee- Aboussafy, C.; Price, K. E.; Hawkins, J. M.; Vaidyanathan, R. Manuscript in preparation.


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