{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:53:07Z","timestamp":1760151187323,"version":"build-2065373602"},"reference-count":27,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2022,2,10]],"date-time":"2022-02-10T00:00:00Z","timestamp":1644451200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/00313\/2020","UIDP\/00313\/2020","UIDB\/004564\/2020","UIDP\/004564\/2020"],"award-info":[{"award-number":["UIDB\/00313\/2020","UIDP\/00313\/2020","UIDB\/004564\/2020","UIDP\/004564\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molbank"],"abstract":"<jats:p>The Diels\u2013Alder reaction of ethyl 3-(1-phenyl-1H-tetrazol-5-yl-1,2-diaza-1,3-butadiene-1-carboxylate with 2-acetyl-6-methyl-2,3-dihydro-4H-pyran (methyl vinyl ketone dimer) regioselectively afforded the corresponding 3-(tetrazol-5-yl)-hexahydro-7H-pyrano[2,3-c]pyridazine in quantitative yield. An X-ray crystal structure of this cycloadduct is reported.<\/jats:p>","DOI":"10.3390\/m1338","type":"journal-article","created":{"date-parts":[[2022,2,9]],"date-time":"2022-02-09T21:22:15Z","timestamp":1644441735000},"page":"M1338","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Ethyl 7-Acetyl-8a-methyl-3-(1-phenyl-1H-tetrazol-5-yl)-1,4,4a,5,6,8a-hexahydro-7H-pyrano[2,3-c]pyridazine-1-carboxylate"],"prefix":"10.3390","volume":"2022","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1580-5667","authenticated-orcid":false,"given":"Susana M. M.","family":"Lopes","sequence":"first","affiliation":[{"name":"University of Coimbra, Coimbra Chemistry Centre (CQC) - Institute of Molecular Sciences (IMS), Department of Chemistry, 3004-535 Coimbra, Portugal"}]},{"given":"Am\u00e9rico","family":"Lemos","sequence":"additional","affiliation":[{"name":"CQC-IMS and Departamento de Qu\u00edmica e Farm\u00e1cia, Faculdade de Ci\u00eancias e Tecnologia, Universidade do Algarve, 8005-139 Faro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4634-7395","authenticated-orcid":false,"given":"Jos\u00e9 A.","family":"Paix\u00e3o","sequence":"additional","affiliation":[{"name":"University of Coimbra, CFisUC, Department of Physics, 3004-530 Coimbra, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3256-4954","authenticated-orcid":false,"given":"Teresa M. V. D.","family":"Pinho e Melo","sequence":"additional","affiliation":[{"name":"University of Coimbra, Coimbra Chemistry Centre (CQC) - Institute of Molecular Sciences (IMS), Department of Chemistry, 3004-535 Coimbra, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,2,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"11324","DOI":"10.1021\/acs.chemrev.8b00375","article-title":"Recent Advances in the Chemistry of Conjugated Nitrosoalkenes and Azoalkenes","volume":"118","author":"Lopes","year":"2018","journal-title":"Chem. 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