Transfer Hydrogenation with Hantzsch Ester

Transfer Hydrogenation with Hantzsch Ester

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  • General Characteristics

Dihydropyridine (Diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate) synthesized from formaldehyde and ethyl acetoacetate is commonly called the Hantzsch ester.

The Hantzsch ester is used as a hydride donor reagent in reduction reactions, often with organocatalysts or photo-redox catalysts. It can be regarded as the chemical analogue of NADH (the biological reductant), since they share the dihydropyridine active structure.

  • General References

  • Norcross, B. E., Klinedinst, Jr., P. E., Westheimer, F. H. J. Am. Chem. Soc. 196284, 797. DOI: 10.1021/ja00864a024
  • Singh, S.; Sharma, V. K.; Gill, S.; Sahota, R. I. K. J. Chem. Soc. Perkin Trans. 1. 1985, 437. DOI: 10.1039/P19850000437
  • Reaction Mechanism

  • Examples

Asymmetric conjugate reduction of α,β-unsaturated aldehydes with Hantzsh ester catalyzed by MacMillan’s imidazolidinone catalyst.[1]

Metal-free and chemoselective reduction of amide.[2]

Asymmetric reduction of quinolines catalyzed by the Terada-Akiyama phosphoric acid catalyst.[3]

  • Experimental Procedure

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  • References

  1. Ouellet, S. G.; Tuttle, J. B.; MacMillan, D. W. C. J. Am. Chem. Soc2005128, 32. DOI: 10.1021/ja043834g
  2. (a) Barbe, G.; Charette, A. B. J. Am. Chem. Soc2008130, 18. DOI: 10.1021/ja077463q (b) Improvement with Et3SiH: Pelletier, G.; Bechara, W. S.; Charette, A. B. J. Am. Chem. Soc2010132, 12817. DOI: 10.1021/ja105194s
  3. Rueping, M.; Theissmann, T. Chem. Sci. 20101, 473. DOI: 10.1039/C0SC00206B
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