M. Hogale, S. Shirke, D. Kharade
Jan 3, 1995
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ChemInform
Abstract
2-(2,4-Dimethylphenoxy)propionic acid was prepared by the reaction of 2,4-dimethylphenol with 2-chloropropionic acid in presence of alkali followed by its polyphosphoric acid cyclisation to yield 2,5,7trimethylbenzofuran-3(1H)-one (3). The formation of 3 was evidenced by disappearance of acidic OH signal at 0 1 0.4 in its pmr spectrum and a broad band around 3 500 cm-1 in ir spectrum. Compound 3 was further converted into 4 by reacting with ethyl chloroformate in acetone using potassium carbonate as a base. The formation of 4 was established by appearance of ester C=O band at 1 760 cm-1 in ir spectrum and a triplet at 0 1.1 and quartet at 8 4.2 in pmr spectrum. Compound 3 on nucleophilic acylation with substituted hydrazides followed by mtramolecular cyclisation in methanol yielded target molecule N1-substituted benzofuro[2,3-c ]pyrazoi3(1H)-ones. The formation of 5 was confirmed by the disappearance of ester C=O band and appearance of two amido C=O bands at 1 700 and 1 665 em -I in its ir spectrum (Scheme I).