Ring Transformations Of Heterocycles Research Articles

ChemInform Abstract: Dimroth Rearrangement: Translocation of Heteroatoms in Heterocyclic Rings and Its Role in Ring Transformations of Heterocycles

Publisher Summary This chapter discusses the translocation of heteroatoms in heterocyclic rings and its role in ring transformation of heterocycles in dimorth rearrangement. The Dimroth rearrangement is an isomerization process whereby exoand endocyclic heteroatoms are translocated on a heterocyclic ring. It is also considered to be amidine rearrangement. This rearrangement may be classified into two main types. The translocation of heteroatoms in the first type can be between two rings of a fused system by three possible pathways: (1) an exocyclic heteroatom of a ring becomes endocyclic, (2) a heteroatom in a five-membered ring changes its location on the other ring, or (3) one of the heteroatoms of a five-membered ring becomes a substituent on the other ring and the other two heteroatoms of the same ring become a part of another five-membered ring on cyclization. The second major type involves the translocation of exo- and endocyclic heteroatoms on a single heterocyclic ring, an exoannular rearrangement, the mechanism of which has been studied since the early work on the subject. The rearrangement led to a translocation of the starred heteroatom. The Dimroth rearrangement can be catalyzed by alkali, acid, heat, or light.

Ring Transformations of Heterocycles 2. Ring Contraction of 5,6-Dihydro-4H-1,2,4,5-oxatriazines into 1H-1,2,4-Triazoles

6-Monosubstituted 5,6-dihydro-4H-1,2,4,5-oxatriazines (3) undergo ring contraction, via elimination of H 2 O, to yield the respective 1H-1,2,4-triazoles (4). This transformation is envisaged to proceed via the ring-opened (E)-hydrazonoxime (5) which then suffers dehydrative cyclization. The process is acid-catalyzed and is thermally induced. Apparently, the driving force for this transformation is linked to the aromaticity of the triazole product

Ring transformations of heterocycles. 35. Potassium amide induced ring transformation of 1,2,4-triazines into 1,2,4-triazoles and 1,3,5-triazines

Ring transformations of heterocycles. 35. Potassium amide induced ring transformation of 1,2,4-triazines into 1,2,4-triazoles and 1,3,5-triazines

Ring transformations of heterocycles with nucleophilic reagents. 34. Frontier-orbital interactions in the reaction of 5-nitropyrimidine with electron-rich olefins. An example of superjacent orbital control

Regiospecificite et stereoselectivite de l'addition du dimorpholino-1,1 ethylene a la nitro-5 pyrimidine

Ring transformations of heterocycles with nucleophiles. 32. Cycloadditions of 5-nitropyrimidines with ynamines. Synthesis and crystal structure of a 2,2a-dihydroazeto[2,3-d]-3,5-diazocine, a novel heterocycle

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRing transformations of heterocycles with nucleophiles. 32. Cycloadditions of 5-nitropyrimidines with ynamines. Synthesis and crystal structure of a 2,2a-dihydroazeto[2,3-d]-3,5-diazocine, a novel heterocycleA. T. M. Marcelis, H. C. Van der Plas, and S. HarkemaCite this: J. Org. Chem. 1985, 50, 2, 270–272Publication Date (Print):January 1, 1985Publication History Published online1 May 2002Published inissue 1 January 1985https://doi.org/10.1021/jo00202a023RIGHTS & PERMISSIONSArticle Views119Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (424 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

ChemInform Abstract: Ring Transformations of Heterocycles via Ylide Intermediates: Synthesis of Hexahydro‐2,3‐diazepino[5,4‐b]indoles from Tetrahydro‐γ‐carbolines.

Chemischer InformationsdienstVolume 13, Issue 33 Heterocyclic Compounds ChemInform Abstract: Ring Transformations of Heterocycles via Ylide Intermediates: Synthesis of Hexahydro-2,3-diazepino[5,4-b]indoles from Tetrahydro-γ-carbolines. Y. TAMURA, Y. TAMURASearch for more papers by this authorI. MORITA, I. MORITASearch for more papers by this authorH. TSUBOUCHI, H. TSUBOUCHISearch for more papers by this authorH. IKEDA, H. IKEDASearch for more papers by this authorM. IKEDA, M. IKEDASearch for more papers by this author Y. TAMURA, Y. TAMURASearch for more papers by this authorI. MORITA, I. MORITASearch for more papers by this authorH. TSUBOUCHI, H. TSUBOUCHISearch for more papers by this authorH. IKEDA, H. IKEDASearch for more papers by this authorM. IKEDA, M. IKEDASearch for more papers by this author First published: August 17, 1982 https://doi.org/10.1002/chin.198233234Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume13, Issue33August 17, 1982 RelatedInformation

Ring Transformations of Heterocycles; A Synthetic Tool

Ring Transformations of Heterocycles; A Synthetic Tool

Ring transformations of heterocycles by oxidizing agents. A 14C study of the conversion of cinnolines into indazoles

Abstract5‐Nitro‐ and S‐nitro[4‐14C]cinnoline have been prepared. Oxidation of those compounds by hydrogen peroxide in acetic acid gave 4‐nitro[3‐14C]‐ and 7‐nitro[3‐14C]indazole, respectively. The indazoles have nearly the same specific radioactivity as the cinnolines, leading to the conclusion that only the C(3) atom of the cinnoline ring is expelled. A mechanism for the ring transformation is proposed.