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33.4.18.1.1.1.3 Variation 3: Miscellaneous Approaches

DOI: 10.1055/sos-SD-033-00648

Quirion, J.-C.; Leclerc, E.; Jubault, P.Science of Synthesis, (200733603.

The Hantzsch-type reactions depicted previously require considerable thermal activation, and room temperature procedures might thus be of interest. Several chemically activated variations of the Hantzsch reaction have been reported which provide some solutions to this problem. For example, an iodotrimethylsilane-mediated condensation of the aldehyde with ethyl acetoacetate, in the presence of ammonium acetate, allows the reaction to proceed at room temperature.[‌14‌] The procedure is efficient with various aliphatic and aromatic aldehydes, including the usually low-yielding 2-substituted benzaldehydes, and the reaction is complete within 8 hours, producing 1,4-dihydropyridines 3 (Scheme 4).

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References