Two-step synthesis of β-alkyl chalcones and their use in the synthesis of 3,5-diaryl-5-alkyl-4,5-dihydropyrazoles

We report a simple and efficient two-step synthesis of variously substituted beta-alkyl chalcones (7) from the corresponding Weinreb amide and a terminal alkyne, and that these chalcones are useful intermediates for the synthesis of medicinally interesting 3,5-diaryl-5-alkyl-4,5-dihydropyrazoles (6). The current methodology allows for the incorporation of many substitution patterns not available from the few previously reported approaches to compounds in this class. (C) 2003 Elsevier Ltd. All rights reserved.