Intramolecular 1,4-Dipolar Cycloadditions of Cross-Conjugated Heteroaromatic Betaines. Synthesis of Hexahydrojulolidines and Related Peri- and Ortho-Fused Ring Systems
| dc.contributor.author | Potts, K.T.; | en |
| dc.contributor.author | Rochanapruk, T.; | en |
| dc.contributor.author | Padwa, A.; | en |
| dc.contributor.author | Coats, S.J.; | en |
| dc.contributor.author | Hadjiarapoglou, L. | en |
| dc.date.accessioned | 2015-11-24T16:40:26Z | |
| dc.date.available | 2015-11-24T16:40:26Z | |
| dc.identifier.uri | https://olympias.lib.uoi.gr/jspui/handle/123456789/8278 | |
| dc.rights | Default Licence | - |
| dc.title | Intramolecular 1,4-Dipolar Cycloadditions of Cross-Conjugated Heteroaromatic Betaines. Synthesis of Hexahydrojulolidines and Related Peri- and Ortho-Fused Ring Systems | en |
| heal.abstract | 3-Alkenyl2-lactams react with (chlorocarbony1)phenylketene to give nonisolable anhydro-4-hydroxy-2-oxo-1,3-oxazinium hydroxides which undergo regio- and stereospecific 1,4-dipolar cycloaddition in moderate yields to produce cycloadducts containing a carbon dioxide bridge. Thermolysis of the cycloadduct led to extrusion of carbon dioxide via a nonconcerted 1,5-hydrogen shift to give julolidinetype derivatives. Two of the cycloadducts were characterized by single-crystal X-ray determinations. A significant enhancement in the overall yield of the cycloaddition occurred in related reactions using anhydro-4-hydroxy-2-oxo-1,3-thiazinihuym droxides obtained from 3-alkenyl-3-ethyl(or methyl) 2-thiolactams and a variety of 1,3-bielectrophiles such as (chlorocarbonyllphenylketene, carbon suboxide, substituted malonyl dichlorides, and ethy (chlorocarbonyllacetate. The thiazinium betaines were often isolable, and in one instance, a single-crystal X-ray characterization was possible. Cycloaddition of the thiazinium betaines occurred in a regiospecific manner. The initially formed cycloadducts which retained the carbonyl sulfide bridge could be induced to lose COS on further heating. Julolidine-type derivatives were obtained principally via a nonconcerted process. Variation in lactam ring size, coupled with tether length and substituent in the 1,3-bielectrophile, enabled control of ring size, substituents, and whether an ortho- orperi-fused tricyclic system resulted from the overall cycloaddition. In contrast to the lactam system, the thiolactams require disubstitution in the 3-position to avoid proton loss in the intermediate betaine with formation of a 1,3-thiazoline- 4,6-dione. | en |
| heal.access | campus | - |
| heal.fullTextAvailability | TRUE | - |
| heal.identifier.primary | 10.1021/jo00117a035 | - |
| heal.identifier.secondary | http://pubs.acs.org/doi/abs/10.1021/jo00117a035 | - |
| heal.journalName | J. Org. Chem. | en |
| heal.journalType | peer reviewed | - |
| heal.language | en | - |
| heal.publicationDate | 1995 | - |
| heal.publisher | American Chemical Society | en |
| heal.recordProvider | Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας | el |
| heal.type | journalArticle | - |
| heal.type.el | Άρθρο Περιοδικού | el |
| heal.type.en | Journal article | en |
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