Nitrones. Part VI. The pyrolysis of oxaziridines derived by photolysis of cyclic nitrones

A Computational Study on the Photochemistry of 2,4,4‐Trimethyl‐1‐pyrroline 1‐Oxide and Investigation on the Reaction Paths of Its Photoproduct Oxaziridine

“…A high energy barrier was required to form lactam through breaking of the C–CH 3 bond adjacent to the nitrogen. These results supported the experimental observations of Todd group and Lamchen group, reported almost sixty years back. The latter group carried out photo‐irradiation and pyrolysis studies on several other cyclic nitrone systems, as well.…”

“…Products obtained from the heating of the oxaziridine obtained due to the photo‐irradiation of 2,4,4‐trimethyl‐pyrroline‐1‐oxide are N‐acetyl azetidine, pyrroline and pyrrolidone. At 150 0 C, the 4‐membered cyclic species and pyrroline are the reported products (in liquid phase), while heating the oxaziridine at 300 0 C in a sealed tube (in vapour phase) produces the lactam and azetidine . Considering the fact that the reaction at 150 0 C occurs in liquid phase, it would be better to compare our observed results with the reported ones at 300 0 C which occurs in vapour phase.…”

The mechanism of photoconversion of cyclic dinitrone to oxaziridine and dioxaziridine: A computational investigation of an experimentally reported photochemical reaction

“…The latter, on heating was found to form the lactam (pyrrolidone) and N-acetyl azetidine. [7] Nature of this cyclic nitrone is quite different in comparison with 5,5-dimethyl-1-pyrroline 1-oxide (DMPO) [4] and its 2-methyl-substituted analogue (2-Me-DMPO). [5] In recent years, our group has proposed [10][11][12][13] the possible mechanism of photo-isomerization for most of these above-mentioned systems through high-level computational studies.…”

“…The latter, on heating was found to form the lactam (pyrrolidone) and N ‐acetyl azetidine. [ 7 ] Nature of this cyclic nitrone is quite different in comparison with 5,5‐dimethyl‐1‐pyrroline 1‐oxide (DMPO) [ 4 ] and its 2‐methyl‐substituted analogue (2‐Me‐DMPO). [ 5 ]…”

“…Experimental studies on the photochemistry of both acyclic and cyclic nitrones started almost 60 years back. Acyclic nitrones were primarily studied by Splitter et al [1,2] and Boyd et al [3] On the other hand, investigations on the cyclic nitrones were first reported by Todd group, [4] followed by Kaminsky et al [5][6][7] and Black's group [8,9] almost at the same time. All these results suggested that the nitrone undergoes photoisomerization to form oxaziridine, which can be stable or unstable depending on the nature of substituents on the nitrogen atom or the adjacent carbon atom.…”