A pyrazole to furan rearrangement. Thermolysis of 5-azido-4-formylpyrazoles

…, KB Simonsen, N Thorup, J Brodersen…

Index: Svenstrup, Niels; Simonsen, Klaus B.; Thorup, Niels; Brodersen, Jorgen; Dehaen, Wim; Becher, Jan Journal of Organic Chemistry, 1999 , vol. 64, # 8 p. 2814 - 2820

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Citation Number: 24

Abstract

5-Azido-3-benzyl-4-formyl-1-phenylpyrazoles 1a-c extrude dinitrogen upon heating in toluene to give the corresponding nitrenes, which immediately rearrange via a new ring- opening ring-closure reaction to produce an equimolar mixture of 4-cyano-2-phenyl-3- phenylazofurans 2a-c and 3-benzyl-4-cyano-1-phenylpyrazoles 3a-c. The formation of the 4- cyano-2-phenyl-3-phenylazofurans 2a-c is the first example in the pyrazole series of a ...