Synthesis of N-Substituted 4-(2-Oxoalkyl)-1,4-dihydronicotinates and Their Inverse Electron Demand Diels-Alder Reaction with 3,4-Dichlorothiophene 1,1-Dioxide

Article abstract of DOI:10.1021/jo00376a051

N-Substituted 4-(2-oxoalkyl)-1,4-dihydronicotinates 4 were prepared in high yields by the reaction of quaternized nicotinium salts with silyl enol ethers.These 1,4-dihydronicotinates acted as dienophiles in Diels-Alder reactions with the electron-deficient 3,4-dichlorothiophene 1,1-dioxide.The cycloaddition proceeded regio- and stereoselectively in good yield to give 1,4,4a,8a-tetrahydroquinolines 8.