Heteroaromatic N-oxide rearrangements. Reinvestigation of 1,3 tosyloxy migration in the reaction of isoquinoline N-oxide with tosyl chloride

Article abstract of DOI:10.1016/S0040-4039(00)79299-9

Isoquinoline N-oxide (2) reacts with ¹⁸O-enriched tosyl chloride to furnish ¹⁸O-labeled 4-tosyloxy-isoquinoline (4), which was assessed for oxygen isotopic enrichment by NMR and mass spectrometry. The 30-45% ¹⁸O incorporation at the bridging oxygen is inconsistent with a high level of the intramolecular tight-ion-pair ('sliding') mechanism. A combination of two intramolecular mechanisms is probably operative.