Unusual Reactions between some 1-Aroyl-4, 5-dihydro-4, 4-dimethyl-5-methylene-1H-pyrazoles and Ketenes

…, J Stephanidou-Stephanatou, A Terzis…

Index: Mitkidou, Sophia; Papadopoulos, Stelios; Stephanidou-Stephanatou, Julia; Terzis, Aristides; Mentzafos, Demetrios Journal of Organic Chemistry, 1990 , vol. 55, # 15 p. 4732 - 4735

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Citation Number: 8

Abstract

5-Methylene-4, 5-dihydropyrazoles la-d react with diphenylketene (DPK), affording the pyrazolyl-3, 3-diphenyl-2-propenyl benzoates 2a-d, very likely via the corresponding pyrazolyl-enol esters 7 as intermediates. By acid hydrolysis of 2 the (diphenyloxopropy1) pyrazole derivative 3 in its enol form is isolated, whereas by cycloaddition with 4- methylbenzonitrile oxide the spiro compound 4 is obtained. 5-Methylene-4, 5- ...