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The oxidative rearrangement of furan-2-carboximidamides: preparation and properties of 2-acylaminofurans

Lookup NU author(s): Emeritus Professor Bill Clegg

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Abstract

Oxidation of furan-2-carboximidamides 8 by (dicarboxyiodo)benzenes gives N-1-acyl-N-1-(2-furyl)ureas 9 via rearrangement to a carbodiimide. Thermolysis of eleven ureas 9 gave the corresponding 2-acylaminofurans 10, which cannot be made from the free amines owing to their high instability. When oxidation of the corresponding benzo[b]furan derivatives 12 was investigated a new type of product was isolated, in addition to the expected ureas 14, and these were shown to be benzo[4,5]furo[2,3-d]pyrimidine derivatives 15. The mechanism of formation of these products must involve reaction of the carbodiimide intermediate with the amidine precursor and cyclisation of the resulting guanidine derivatives 19. The corresponding tetraphenylguanidine 21 was prepared and underwent thermal cyclisation but the quinazoline derivative formed 23 was shown to occur via an alternative cyclisation mechanism. The structures of cyclisation products 15 and 23 were confirmed by X-ray crystallography. N-(2-Furyl)acetamide 10a readily undergoes cycloaddition reactions with electron-deficient alkynes to give phenols after spontaneous ring opening. Observed regioselectivity is in agreement with the results of AM1 molecular orbital calculations. Reaction of the amide 10a with Lawesson's reagent gave the thioamide 26.


Publication metadata

Author(s): Bobsikova M, Clegg W, Coles SJ, Dandarova M, Hursthouse MB, Kiss T, Krutosikova A, Liptaj T, Pronayova N, Ramsden CA

Publication type: Article

Publication status: Published

Journal: Journal of the Royal Chemical Society: Perkin Transactions 1

Year: 2001

Issue: 7

Pages: 680-689

ISSN (print): 1472-7781

ISSN (electronic): 1364-5463

Publisher: Royal Society of Chemistry

URL: http://dx.doi.org/10.1039/B010010M

DOI: 10.1039/B010010M


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