A variety of substituted 4H-pyrans are readily prepared in moderate to good yields under the mild reaction conditions by nucleophilic addition to electron-deficient 1,3-conjugated enynes with phase-transfer catalysis (PTC).
在温和的反应条件下,通过相转移催化(
PTC)与缺电子的 1,3-共轭炔进行亲核加成,很容易制备出各种取代的
4H-吡喃,产率从中等到良好不等。