Six-membered cyclic nitronates as Brönsted bases: protonation and rearrangement into butyrolactone oximes

The protonation of six-membered cyclic nitronates (SMCNs) was studied by low-temperature NMR spectroscopy, and an efficient preparative procedure for acid-induced rearrangement of SMCNs into oximes of substituted butyrolactones was developed.