Efficient and Rapid Synthesis of Highly Functionalized Novel Symmetric 1,4-Dihydropyridines Using Glacial Acetic Acid as Solvent

Abstract

A new series of 1,4-dihydropyridines bearing a pyrazole moiety in the 4-position were synthesized by a variation of the classical Hantzsch synthesis. The reaction of 1,3-diphenyl-1H-pyrazole-4-carbaldehyde 4a–n with 3-amino crotononitrile in the presence of glacial acetic acid afforded novel 3,5-dicyano-2,6-dimethyl 1,4-dihydropyridines 5a–n. The procedure has short reaction time (15–20 min), easy workup, and good yield of product. The structures of all synthesized compounds were well characterized by mass, infrared, ¹H and ¹³C NMR, and elemental analysis.

GRAPHICAL ABSTRACT

Keywords:

• 1,4-Dihydro pyridines
• glacial acetic acid
• pyrazole aldehyde

ACKNOWLEDGMENTS

The authors are thankful to the Funding for Infrastructure in Science and Technology–Department of Science and Technology and Special Assistant Programme (SAP)–University Grants Commission for their generous financial and instrumentation support. Special thanks are due to the National Facility for Drug Discovery through New Chemical Entities (NCEs) Development and Instrumentation Support to Small Manufacturing Pharma Enterprises Program under the Drug and Pharma Research Support jointly funded by the Department of Science and Technology, New Delhi, Government of Gujarat Industries Commissionerate, and Saurashtra University, Rajkot.

Notes

^a Isolated yields after purification.

^a Isolated yields after purification.