Oxidative Ring Expansion of Spirocyclic Oxindole Derivatives
2014 (English)In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 19, 9065-9073 p.Article in journal (Refereed) Published
Oxidation of the spirocyclic oxindole derivative, isamic acid 1, led to decarboxylation and ring expansion to quinazolino[4,5-b]quinazoline-6,8-dione 7 rather than, as previously believed, its isomer 6. The structure of 7 was confirmed by X-ray crystallography. Condensation of isatin (indole-2,3-dione) and 2-aminobenzamide led to the spirocyclic molecule, spiro[3H-indole-3,2'(1H)quinazoline]-2,4'(1H,3H)dione 8, which was also identified as an intermediate in the oxidation of isamic acid. Mild hydrolysis of 7 gave the 10-membered molecule 22. Isamic acid could easily be converted to N-nitrosoisamic acid, which when heated in ethanol underwent a ring expansion to a hydroximino derivative, 38, of compound 6. The structure of 38 was confirmed by X-ray crystallography.
Place, publisher, year, edition, pages
2014. Vol. 79, no 19, 9065-9073 p.
IdentifiersURN: urn:nbn:se:kth:diva-155461DOI: 10.1021/jo501269fISI: 000342719600013ScopusID: 2-s2.0-84907802947OAI: oai:DiVA.org:kth-155461DiVA: diva2:762929
QC 201411132014-11-132014-11-062014-11-13Bibliographically approved