{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,20]],"date-time":"2025-10-20T17:24:36Z","timestamp":1760981076057,"version":"build-2065373602"},"reference-count":35,"publisher":"Wiley","issue":"12","license":[{"start":{"date-parts":[[2006,3,31]],"date-time":"2006-03-31T00:00:00Z","timestamp":1143763200000},"content-version":"vor","delay-in-days":0,"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":[[2006,6]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The synthesis of pyrazoles <jats:bold>13<\/jats:bold>\u2013<jats:bold>24<\/jats:bold> has been accomplished by treatment of 3\u2010benzylchromones <jats:bold>1<\/jats:bold>\u2013<jats:bold>5<\/jats:bold>, 3\u2010benzylflavones <jats:bold>6<\/jats:bold>\u2013<jats:bold>12<\/jats:bold> and their 4\u2010thio analogues <jats:bold>25<\/jats:bold>\u2013<jats:bold>29<\/jats:bold> with hydrazine hydrate in hot pyridine. A plausible reaction mechanism for the formation of pyrazoles <jats:bold>13<\/jats:bold>\u2013<jats:bold>24<\/jats:bold> is discussed. A <jats:sup>1<\/jats:sup>H NMR study in [D<jats:sub>6<\/jats:sub>]DMSO allowed the presence of both pyrazole annular tautomers to be observed, due to the presence of intramolecular hydrogen bonds in each tautomer (<jats:bold>OH\u2010\u2010N<\/jats:bold> and <jats:bold>NH\u2010\u2010O<\/jats:bold>). GIAO\/B3LYP\/6\u2010311++G** calculations were carried out on some model pyrazoles to provide a theoretical basis for the NMR experimental observations.(\u00a9 Wiley\u2010VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2006)<\/jats:p>","DOI":"10.1002\/ejoc.200600043","type":"journal-article","created":{"date-parts":[[2006,3,31]],"date-time":"2006-03-31T11:16:45Z","timestamp":1143803805000},"page":"2825-2832","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":37,"title":["Synthesis of Pyrazoles by Treatment of 3\u2010Benzylchromones, 3\u2010Benzylflavones and Their 4\u2010Thio Analogues with Hydrazine"],"prefix":"10.1002","volume":"2006","author":[{"given":"Albert","family":"L\u00e9vai","sequence":"first","affiliation":[]},{"given":"Artur M. S.","family":"Silva","sequence":"additional","affiliation":[]},{"given":"Jos\u00e9 A. S.","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\u0151","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[2006,5,23]]},"reference":[{"key":"e_1_2_5_1_2","doi-asserted-by":"publisher","DOI":"10.1016\/B978-008096519-2.00072-2"},{"key":"e_1_2_5_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/B978-008096518-5.00059-9"},{"volume-title":"The Chemistry of Heterocycles \u2013 Structure, Reactions, Synthesis and Application","year":"1995","author":"Eicher T.","key":"e_1_2_5_3_2"},{"volume-title":"Pyrazoles as Drugs: Facts and Fantasies","year":"2002","author":"Elguero J.","key":"e_1_2_5_4_2"},{"key":"e_1_2_5_5_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja00158a039"},{"key":"e_1_2_5_6_2","doi-asserted-by":"publisher","DOI":"10.1021\/ja00039a014"},{"key":"e_1_2_5_7_2","first-page":"38","volume":"18","author":"Ahmad R.","year":"1996","journal-title":"J. Chem. Soc. Pak."},{"key":"e_1_2_5_8_2","first-page":"65","volume":"21","author":"Takagi K.","year":"1986","journal-title":"Eur. J. Med. Chem. \u2013 Chim. Ther."},{"key":"e_1_2_5_9_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0040-4020(99)00546-3"},{"key":"e_1_2_5_10_2","doi-asserted-by":"publisher","DOI":"10.1002\/jhet.5570370637"},{"key":"e_1_2_5_11_2","first-page":"3807","author":"Silva A. M. S.","year":"2002","journal-title":"Eur. J. Org. Chem."},{"key":"e_1_2_5_12_2","unstructured":"\u00a0"},{"key":"e_1_2_5_13_2","first-page":"465","volume":"36","author":"L\u00e9vai A.","year":"1981","journal-title":"Pharmazie"},{"key":"e_1_2_5_14_2","first-page":"359","volume":"128","author":"L\u00e9vai A.","year":"1991","journal-title":"Acta Chim. Hung."},{"key":"e_1_2_5_15_2","first-page":"976","volume":"128","author":"L\u00e9vai A.","year":"1991","journal-title":"Bull. Soc. Chim. Fr."},{"key":"e_1_2_5_16_2","first-page":"380","author":"L\u00e9vai A.","year":"1992","journal-title":"J. Chem. Research (S)"},{"key":"e_1_2_5_17_2","first-page":"163","author":"L\u00e9vai A.","year":"1992","journal-title":"J. Chem. Research (S)"},{"key":"e_1_2_5_18_2","doi-asserted-by":"publisher","DOI":"10.1002\/bscb.19780870310"},{"key":"e_1_2_5_19_2","doi-asserted-by":"publisher","DOI":"10.1002\/ejoc.200400465"},{"key":"e_1_2_5_20_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0065-2725(00)76005-3"},{"key":"e_1_2_5_21_2","doi-asserted-by":"publisher","DOI":"10.1002\/mrc.1481"},{"key":"e_1_2_5_22_2","first-page":"5","author":"Claramunt R. M.","year":"2006","journal-title":"ARKIVOC"},{"key":"e_1_2_5_23_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.tet.2005.03.035"},{"key":"e_1_2_5_24_2","doi-asserted-by":"publisher","DOI":"10.1039\/b103405g"},{"key":"e_1_2_5_25_2","doi-asserted-by":"publisher","DOI":"10.3390\/i4030064"},{"key":"e_1_2_5_26_2","unstructured":"\u00a0"},{"key":"e_1_2_5_27_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.464913"},{"key":"e_1_2_5_28_2","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevB.37.785"},{"key":"e_1_2_5_29_2","doi-asserted-by":"publisher","DOI":"10.1063\/1.1674902"},{"key":"e_1_2_5_29_3","doi-asserted-by":"publisher","DOI":"10.1063\/1.447079"},{"key":"e_1_2_5_30_2","unstructured":"M. J. Frisch G. W. Trucks H. B. Schlegel G. E. Scuseria M. A. Robb J. R. Cheeseman J. A. Montgomery Jr T. Vreven K. N. Kudin J. C. Burant J. M. Millam S. S. Iyengar J. Tomasi V. Barone B. Mennucci M. Cossi G. Scalmani N. Rega G. A. Petersson H. Nakatsuji M. Hada M. Ehara K. Toyota R. Fukuda J. Hasegawa M. Ishida T. Nakajima Y. Honda O. Kitao H. Nakai M. Klene X. Li J. E. Knox H. P. Hratchian J. B. Cross C. Adamo J. Jaramillo R. Gomperts R. E. Stratmann O. Yazyev A. J. Austin R. Cammi C. Pomelli J. W. Ochterski P. Y. Ayala K. Morokuma G. A. Voth P. Salvador J. J. Dannenberg V. G. Zakrzewski S. Dapprich A. D. Daniels M. C. Strain O. Farkas D. K. Malick A. D. Rabuck K. Raghavachari J. B. Foresman J. V. Ortiz Q. Cui A. G. Baboul S. Clifford J. Cioslowski B. B. Stefanov G. Liu A. Liashenko P. Piskorz I. Komaromi R. L. Martin D. J. Fox T. Keith M. A. Al\u2010Laham C. Y. Peng A. Nanayakkara M. Challacombe P. M. W. Gill B. Johnson W. Chen M. W. Wong C. Gonzalez and J. A. Pople Gaussian 03 Gaussian Inc. Pittsburgh PA 2003."},{"key":"e_1_2_5_31_2","unstructured":"\u00a0"},{"key":"e_1_2_5_32_2","doi-asserted-by":"publisher","DOI":"10.1080\/00268977400100711"},{"key":"e_1_2_5_33_2","doi-asserted-by":"publisher","DOI":"10.1051\/jphysrad:01937008010039700"},{"key":"e_1_2_5_34_2","doi-asserted-by":"publisher","DOI":"10.1016\/0301-0104(81)85090-2"}],"container-title":["European Journal of Organic Chemistry"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fejoc.200600043","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/chemistry-europe.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/ejoc.200600043","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,13]],"date-time":"2025-10-13T17:44:21Z","timestamp":1760377461000},"score":1,"resource":{"primary":{"URL":"https:\/\/chemistry-europe.onlinelibrary.wiley.com\/doi\/10.1002\/ejoc.200600043"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2006,5,23]]},"references-count":35,"journal-issue":{"issue":"12","published-print":{"date-parts":[[2006,6]]}},"alternative-id":["10.1002\/ejoc.200600043"],"URL":"https:\/\/doi.org\/10.1002\/ejoc.200600043","archive":["Portico"],"relation":{},"ISSN":["1434-193X","1099-0690"],"issn-type":[{"type":"print","value":"1434-193X"},{"type":"electronic","value":"1099-0690"}],"subject":[],"published":{"date-parts":[[2006,5,23]]},"assertion":[{"value":"2006-01-18","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2006-05-23","order":3,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}