Publisher Summary This chapter reviews meso-ionic heterocycles. It discusses the currently known types of meso-ionic heterocycles, which can then be considered in relation to the total number of possibilities associated with certain structural conditions. A compound may be appropriately called meso-ionic if it is a five or possibly a six-membered heterocyclic compound that cannot be represented satisfactorily by any one covalent or polar structure and possesses a sextet of electrons in association with the atoms comprising the ring. The ring bears a fractional positive charge balanced by a corresponding negative charge located on a covalently attached atom or group of atoms. The adoption of the term meso-ionic and its frequent use has demonstrated its usefulness. The five-membered mesoionic heterocycles can be divided into two general classes: type A and type B. This chapter is concerned with the currently known 44 members of type A and eight members of type B.
{"title":"Meso-ionic compounds","authors":"W. Baker, W. Ollis","doi":"10.1039/QR9571100015","DOIUrl":"https://doi.org/10.1039/QR9571100015","url":null,"abstract":"Publisher Summary This chapter reviews meso-ionic heterocycles. It discusses the currently known types of meso-ionic heterocycles, which can then be considered in relation to the total number of possibilities associated with certain structural conditions. A compound may be appropriately called meso-ionic if it is a five or possibly a six-membered heterocyclic compound that cannot be represented satisfactorily by any one covalent or polar structure and possesses a sextet of electrons in association with the atoms comprising the ring. The ring bears a fractional positive charge balanced by a corresponding negative charge located on a covalently attached atom or group of atoms. The adoption of the term meso-ionic and its frequent use has demonstrated its usefulness. The five-membered mesoionic heterocycles can be divided into two general classes: type A and type B. This chapter is concerned with the currently known 44 members of type A and eight members of type B.","PeriodicalId":50864,"journal":{"name":"Advances in Heterocyclic Chemistry","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1039/QR9571100015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58126115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1016/bs.aihch.2021.08.001
Ismail A. Abdelhamid, M. Shaaban, Ahmed H. M. Elwahy
{"title":"Applications of the Vilsmeier reaction in heterocyclic chemistry","authors":"Ismail A. Abdelhamid, M. Shaaban, Ahmed H. M. Elwahy","doi":"10.1016/bs.aihch.2021.08.001","DOIUrl":"https://doi.org/10.1016/bs.aihch.2021.08.001","url":null,"abstract":"","PeriodicalId":50864,"journal":{"name":"Advances in Heterocyclic Chemistry","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54034611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1016/bs.aihch.2021.09.001
B. Pintea, Vasile N. Bercean, V. Badea
{"title":"The synthesis of pyrazolo[5,1-c][1,2,4]triazoles. Part 2: From bicyclic precursors. Annulated pyrazolo[5,1-c][1,2,4]triazoles","authors":"B. Pintea, Vasile N. Bercean, V. Badea","doi":"10.1016/bs.aihch.2021.09.001","DOIUrl":"https://doi.org/10.1016/bs.aihch.2021.09.001","url":null,"abstract":"","PeriodicalId":50864,"journal":{"name":"Advances in Heterocyclic Chemistry","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54034716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1016/bs.aihch.2021.10.002
Yingchun Wang, Tomas Opsomer, W. Dehaen
{"title":"Developments in the chemistry of 1,3a,6a-triazapentalenes and their fused analogs","authors":"Yingchun Wang, Tomas Opsomer, W. Dehaen","doi":"10.1016/bs.aihch.2021.10.002","DOIUrl":"https://doi.org/10.1016/bs.aihch.2021.10.002","url":null,"abstract":"","PeriodicalId":50864,"journal":{"name":"Advances in Heterocyclic Chemistry","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54034865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1016/bs.aihch.2021.09.002
L. I. Belen’kii, G. Gazieva, Yu. B. Evdokimenkova, N. O. Soboleva
{"title":"The literature of heterocyclic chemistry, Part XIX, 2019","authors":"L. I. Belen’kii, G. Gazieva, Yu. B. Evdokimenkova, N. O. Soboleva","doi":"10.1016/bs.aihch.2021.09.002","DOIUrl":"https://doi.org/10.1016/bs.aihch.2021.09.002","url":null,"abstract":"","PeriodicalId":50864,"journal":{"name":"Advances in Heterocyclic Chemistry","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54034757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.1016/bs.aihch.2020.12.002
A. C. Pippione, Stefano Sainas, D. Boschi, M. Lolli
{"title":"Hydroxyazoles as acid isosteres and their drug design applications—Part 2: Bicyclic systems","authors":"A. C. Pippione, Stefano Sainas, D. Boschi, M. Lolli","doi":"10.1016/bs.aihch.2020.12.002","DOIUrl":"https://doi.org/10.1016/bs.aihch.2020.12.002","url":null,"abstract":"","PeriodicalId":50864,"journal":{"name":"Advances in Heterocyclic Chemistry","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/bs.aihch.2020.12.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54034563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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