Chemoselective cycloadditions of 3,4-dialkoxyfurans and alkyl coumalates. Novel loss of aromaticity of two nonbenzenoid aromatic rings in a mild thermal process
作者:Michael E. Jung、Leslie J. Street、Yoshihiro. Usui
DOI:10.1021/ja00281a062
日期:1986.10
either dienes or dienophiles in cycloadditions depending on their reaction partners. They have often been used as dienophiles with simple substituted butadienes 2, giving good yields of the Diels-Alder adducts 3 involving the 5,6-double bond of the pyrone as the dienophile, a useful process for trichothecane synthesis3 However, with highly electron-rich olefins, e.g., the ketene acetal 4, they react as