Reaction of 3-arylidenepropenoic acid derivatives with triethylamine and other amines; unexpected reductions and vinylogations
作者:Attimogae Shivamurthy Harisha、Suresh Parameshwar Nayak、Kuppuswamy Nagarajan、Tayur Narasingarow Guru Row、Amar A. Hosamani
DOI:10.1016/j.tet.2016.03.097
日期:2016.6
Exposure of ethyl 2-cyano-3-(2-methoxy-5-nitrophenyl)acrylate 1f to triethylamine in hot ethanol resulted in the formation of the dihydro derivative 2f and vinylogue 3f in high yields. Single crystal X-ray data are provided for 3f. Similar reactions were observed for various analogues. The reaction was studied changing aryl substituent, amines and solvents. Pyridyl, thienyl analogues were also examined
view of these observations, an unusual [4+2] cycloaddition of the electron-rich enol 21 with singletoxygen is proposed to be responsible for the formation of products 7 and 16, while products 6, 14 and 15 arise from both the [4+2] cycloaddition and the usual Schenck ene reaction pathways. This special diene reactivity of the isoquinolinone system towards singletoxygen is further interpreted by frontier