1023588-60-4Relevant academic research and scientific papers
Synthesis and thermal transformations of pyrazolines obtained by 1,3-dipolar addition of diazocyclopropane to maleimides
Kostyuchenko,Shulishov,Rafikov,Tomilov, Yu. V.
experimental part, p. 1712 - 1717 (2011/04/23)
1-Pyrazolines, obtained by 1,3-dipolar cycloaddition of diazocyclopropane to N-phenyl- and N-cyclohexylmaleimides, undergo complete dediazoniation at 175 °C for 10-16 h with the formation of spiro[3-azabicyclo[3.1.0]hexane-6, 1′-cyclopropane]-2,4-diones 3 (80-89%) and isomeric 3-cyclopropyl-1H- pyrrole-2,5-diones 4. On the example of 3-cyclopropyl-1-phenyl-1H-pyrrole-2,5- dione, it was shown that compounds 4 are able again to enter into 1,3-dipolar cycloaddition with diazomethane or diazocyclopropane with the reaction in the case of diazocyclopropane being nonselective and leading to two regioisomeric pyrazolines in the ratio ～1.7: 1, thermolysis of which, conversely, proceeds with high selectivity and exclusively affords a spiropentane derivative. An action of the aqueous methanol solution of sodium hydroxide on the spiropentanes fused with succinimide fragment and subsequent acidification of the salts obtained lead to stable cis-amidoacids of spiropentane series.
