Nitrene insertion into an adjacent o -methoxy group followed by nucleophilic addition to the heterocumulene intermediate: Experimental and computational studies

The chemistry of aryl azides and aryl nitrenes is rich and varied in nature with different products being obtained with minor changes in reaction conditions. Thermolysis of azido- dimethylsuccinylosuccinate has been carried out to study the behaviour of this new azide during thermolysis. The products obtained have been studied by various spectroscopic and DFT calculations. These results reveal formation of compound-II and compound-III from the nitrene intermediate (1) generated during the thermolysis process. DFT results rationalized the formation of thermodynamically stable compound-II and compound-III from the stable intermediates 2 and 4 formed during the thermolysis process. Further, DFT results suggest that the reaction between 4 and 2 is thermodynamically more favourable compared to the further thermal degradation of the intermediate 4 to pyridylcarbene (4b) and carbene intermediate (5), which corroborates that such products were not formed during thermolysis.