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Microwave‐Assisted Solution‐Phase Synthesis of 1,4,5‐Trisubstituted Pyrazoles
Author(s) -
Giacomelli Giampaolo,
Porcheddu Andrea,
Salaris Margherita,
Taddei Maurizio
Publication year - 2003
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200390091
Subject(s) - chemistry , scavenger , meldrum's acid , dimethylformamide , microwave irradiation , microwave , organic chemistry , phase (matter) , combinatorial chemistry , radical , catalysis , physics , quantum mechanics , solvent
Abstract A small parallel library of 1,4,5‐trisubstituted pyrazoles was prepared in solution using a three‐step procedure starting from Meldrum acid. The Meldrum acid was acylated with different acyl chlorides and the products opened with different alcohols and amines to give substituted β‐keto esters and β‐keto amines. Further reaction with N , N ‐dimethylformamide dimethylacetal and the final cyclisation were effectively carried out under microwave irradiation. Scavenger resins were employed exclusively in the first step, whereas use of microwaves allowed complete conversion of the starting materials in the other two steps. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)