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Exploiting 3‑oxidopyraziniums toward diazabicyclo [3.2.1] octanes and their conversion into diazabicyclo [2.2.2] octanes and tricyclic lactone-lactams Riesco-Llach, Gerard Planas i Grabuleda, Marta Feliu Soley, Lidia Joule, John A. Reaccions d'addició Addition reactions Ciclització (Química) Ring formation (Chemistry) Compostos orgànics Organic compounds 3-Oxidopyraziniums are azomethine ylides derived from 2(1H)-pyrazinones that can undergo 1,3-dipolar cycloadditions with acrylate and acrylic acid derivatives. The cycloaddition of 1-(4-methoxybenzyl)-5,6-dimethyl-3-oxidopyrazinium with methyl and tert-butyl acrylate and with methyl crotonate afforded a 3,8-diazabicyclo[3.2.1]octane in 51–73% yield together with traces of the 2,5-diazabicyclo[2.2.2]octane. In contrast, cycloaddition of this 3-oxidopyrazinium with methyl 2-phenyl acrylate provided the [2.2.2] product in 40% yield. Herein, we show that the 2,5-diazabicyclo[2.2.2]octanes were formed from the [3.2.1] compounds via a Wagner–Meerwein rearrangement. Remarkably, when acrylic acid and 2-phenylacrylic acid were employed as dipolarophiles, novel tricyclic fused lactone-lactam systems were obtained in 71% and 50% yields, respectively. The formation of these tricyclic compounds can be rationalized via the mechanism described above followed by lactonization of the 2,5-diazabicyclo[2.2.2]octane Open Access funding provided thanks to the CRUE-CSIC agreement with American Chemical Society (ACS) 2024-02-08 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion peer-reviewed 38329899 http://hdl.handle.net/10256/24593 eng info:eu-repo/semantics/altIdentifier/doi/10.1021/acs.joc.3c02273 info:eu-repo/semantics/altIdentifier/issn/0022-3263 info:eu-repo/semantics/altIdentifier/eissn/1520-6904 Attribution 4.0 International http://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess application/pdf American Chemical Society (ACS) The Journal of Organic Chemistry (JOC), 2024, vol. 89, núm. 5, p. 2904-2915 Articles publicats (D-Q)