Solvent-Free Thermal and Microwave-Assisted [3 + 2] Cycloadditions between Stabilized Azomethine Ylides and Nitrostyrenes. An Experimental and Theoretical Study

详细信息    查看全文

• 作者：Ana Arrieta ; Dorleta Otaegui ; Aizpea Zubia ; Fernando P. Coss&iacute ; o ; Angel D&iacute ; az-Ortiz ; Antonio de la Hoz ; M. Antonia Herrero ; Pilar Prieto ; Concepció ; n Foces-Foces ; José ; L. Pizar
• 刊名：Journal of Organic Chemistry
• 出版年：2007
• 出版时间：June 8, 2007
• 年：2007
• 卷：72
• 期：12
• 页码：4313 - 4322
• 全文大小：568K
• 年卷期：v.72,no.12(June 8, 2007)
• ISSN：1520-6904

文摘

D=jo062672zn00001>The stereochemical outcomes observed in the thermal and microwave-assisted [3 + 2] cycloadditionbetween stabilized azomethine ylides and nitrostyrenes have been analyzed using experimental andcomputational approaches. It has been observed that, in the absence of solvent, three stereoisomers areformed, both under classical heating conditions and under microwave irradiation. This result contrastswith that observed in solution under classical thermal conditions. The 4-nitropyrrolidines obtained inthis way can be aromatized under further microwave irradiation to yield mixtures of pyrroles and4-nitropyrroles. It is found that ground state cycloadditions between imines and nitrostyrenes take placeby three-step mechanisms. The first step involves enolization of the starting imine, and this is followedby a pseudopericyclic 10-electron [1.4]-hydrogen shift. Finally, the cycloaddition takes place by a relativelyasynchronous aromatic six-electron supra-supra thermal mechanism.