{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,20]],"date-time":"2025-10-20T17:03:55Z","timestamp":1760979835238,"version":"build-2065373602"},"reference-count":34,"publisher":"Wiley","issue":"22","license":[{"start":{"date-parts":[[2004,11,2]],"date-time":"2004-11-02T00:00:00Z","timestamp":1099353600000},"content-version":"vor","delay-in-days":1,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["chemistry-europe.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Eur J Org Chem"],"published-print":{"date-parts":[[2004,11]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The synthesis of several 1\u2010acetyl\u20103\u2010aryl\u20105\u2010[3\u2010(2\u2010hydroxyphenyl)pyrazol\u20104\u2010yl]\u20102\u2010pyrazolines <jats:bold>3a<\/jats:bold>\u2212<jats:bold>3h<\/jats:bold> has been accomplished by treatment of the 3\u2010(3\u2010aryl\u20103\u2010oxopropenyl)chromen\u20104\u2010ones <jats:bold>1a<\/jats:bold>\u2212<jats:bold>h<\/jats:bold> with hydrazine hydrate in hot acetic acid. The 1\u2010acetyl\u20103\u2010aryl\u20105\u2010(3\u2010chromonyl)\u20102\u2010pyrazolines <jats:bold>2a<\/jats:bold>\u2212<jats:bold>2f<\/jats:bold> were also obtained as by\u2010products. Oxidation of the 1\u2010acetyl\u20104\u2010pyrazolyl\u20102\u2010pyrazolines <jats:bold>3a<\/jats:bold>\u2212<jats:bold>3f<\/jats:bold> with DDQ gave the 3(5)\u2010aryl\u20105(3)\u2010[3\u2010(2\u2010hydroxyphenyl)pyrazol\u20104\u2010yl]pyrazoles <jats:bold>5a<\/jats:bold>\u2212<jats:bold>5f<\/jats:bold>. The oxidation of the 2\u2010pyrazoline rings was accompanied by <jats:italic>N<\/jats:italic>\u2010deacylation. The reaction mechanisms of both transformations are discussed, the first one being supported by experimental results. The structures of all new derivatives were established by NMR and the evidence of prototropic tautomerism is carefully discussed. Theoretical calculations of energies and of the <jats:sup>1<\/jats:sup>H and <jats:sup>13<\/jats:sup>C NMR chemical shifts of the possible tautomeric forms of 5(3)\u2010[3\u2010(2\u2010hydroxyphenyl)pyrazol\u20104\u2010yl]\u20103(5)\u2010(4\u2010methoxyphenyl)pyrazole (<jats:bold>5c<\/jats:bold>), by B3LYP and GIAO, showed that compounds of this type probably exist as mixtures of two tautomers. (\u00a9 Wiley\u2010VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2004)<\/jats:p>","DOI":"10.1002\/ejoc.200400465","type":"journal-article","created":{"date-parts":[[2004,11,2]],"date-time":"2004-11-02T15:46:09Z","timestamp":1099410369000},"page":"4672-4679","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":48,"title":["Synthesis of Pyrazolyl\u20102\u2010pyrazolines by Treatment of 3\u2010(3\u2010Aryl\u20103\u2010oxopropenyl)chromen\u20104\u2010ones with Hydrazine and Their Oxidation to Bis(pyrazoles)"],"prefix":"10.1002","volume":"2004","author":[{"given":"Albert","family":"L\u00e9vai","sequence":"first","affiliation":[]},{"given":"Artur\u00a0M.\u00a0S.","family":"Silva","sequence":"additional","affiliation":[]},{"given":"Diana\u00a0C.\u00a0G.\u00a0A.","family":"Pinto","sequence":"additional","affiliation":[]},{"given":"Jos\u00e9\u00a0A.\u00a0S.","family":"Cavaleiro","sequence":"additional","affiliation":[]},{"given":"Ibon","family":"Alkorta","sequence":"additional","affiliation":[]},{"given":"Jos\u00e9","family":"Elguero","sequence":"additional","affiliation":[]},{"given":"J\u00f3zsef","family":"Jek\u00f6","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[2004,11,2]]},"reference":[{"key":"e_1_2_5_1_2","unstructured":"\u00a0"},{"key":"e_1_2_5_2_2","first-page":"388","volume":"42","author":"Polyakov V. 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