Intriguing enigma of nitrobenzofuroxan's 'Sphinx': Boulton-Katritzky rearrangement or unusual evidence of the N-1/N-3-oxide rearrangement?

ABSTRACT: The S_EAr/S_NAr reaction between 7-chloro-4,6-dinitrobenzofuroxan (ClDNBF) and 2-morpholinyl-, 2-piperidinyl-, or 2-pyrrolidinylthiazole afforded unexpectedly two isomeric products, bearing the benzofuroxanyl moiety bound to the C-5 carbon atom of the thiazole ring. The relative ratio for the two isomers was dependent on temperature and solvent, suggesting the occurrence of an equilibrium between the two novel species. In order to investigate their structure and to design a plausible mechanistic pathway, a series of synthetic and spectroscopic experiments was planned. The isomer's structure was unambigously assigned when the reduction of furoxanyl to the furazanyl ring of the products gave exclusively a single species whose NMR data were coincident with those obtained b

SUBMITTER: Micheletti G 

PROVIDER: S-EPMC9056797 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature