On heating, the di-Boc-pyridin-4-one derivative 7 gave an unstable 3-methylenepyridin-4-one intermediate 3, which underwent a rearomatising Diels–Alder cycloaddition with activated alkenes to give substituted pyrano[3,2-c]pyridines in moderate yields.
加热时,二-Boc-
吡啶-4-酮衍
生物7生成不稳定的3-亚
甲基吡啶-4-酮中间体3,将其与活化的烯烃进行Diels-Alder环加成反应,生成取代的
吡喃并[3,2- c ]。
吡啶的产率中等。