H. Morita, S. Shiotani
Sep 1, 1986
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0
Influential Citations
26
Citations
Journal
Journal of Heterocyclic Chemistry
Abstract
This paper describes the synthesis and chemical properties of some 2- and 3-substituted furo[2,3-b]pyridines. Reaction of ethyl 2-chloronicotinate 1 with sodium ethoxycarbonylmethoxide or 1-ethoxycarbonyl-1-ethoxide gave β-keto ester 2 or ketone 5, respectively. Ketonic hydrolysis of 2 afforded ketone 3, from which furo[2,3-b]pyridine 4 was obtained by the method of Sliwa. While, 2-methyl derivative 7 was prepared from 5 by reduction, O-acetylation and the subsequent pyrolysis. Reaction of ketone 3 with methyllithium gave tertiary alcohol 8 which was O-acetylated and pyrolyzed to give 3-methyl derivative 9. Formylation of 4, via lithio intermediate, with DMF yielded 2-formyl derivative 10, from which 7, was obtained by Wolff-Kishner reduction. Dehydration of the oxime 11 of 10 gave 2-cyano derivative 12, which was hydrolyzed to give 2-carboxylic acid 13. Reaction of 3-bromo compound 14 with copper(I) cyanide gave 3-cyano derivative 15. Alkaline hydrolysis of 15 afforded compound 16 and 17, while acidic hydrolysis gave carboxamide 18. Reduction of 15 with DIBAL-H afforded 3-formyl derivative 19. Wolff-Kishner reduction of 19 gave no reduction product 9 but hydrazone 20. Reduction of tosylhydrazone 21 with sodium borohydride in methanol afforded 3-methoxymethylfuro[2,3-b]pyridine 22.