Treatment of a series of 6-alkylthio-, 6-alkylsulfinyl- and 6-alkylsulfonyl-1,2,4-triazines with 1-pyrrolidinocyclopentene yields 3,4-cyclopentenopyridines. The observed rates of these cycloaddition reactions (sulfide < sulfoxide < sulfoxide) are consistent with an inverse electron-demand Diels-Alder reaction.
用1-
吡咯烷基
环戊烯处理一系列6-烷
硫基-,6-烷基亚磺酰基-和6-烷基磺酰基-
1,2,4-三嗪,得到3,4-
环戊烯吡啶。观察到的这些环加成反应的速率(
硫化物<亚砜<亚砜)与电子需求逆Diels-Alder反应一致。