[reaction: see text] Nonenolizable aldehydes and ketones react with 2-chloroethanol and 3-chloropropanol under basic conditions (t-BuOK, DMF/THF) with formation of 2-substituted 1,3-dioxolanes and 1,3-dioxanes, respectively. Conversion of the two-step addition-alkylation process depends on the electrophilicity of the carbonyl group that governs the equilibrium of addition of chloroalkoxides. This method
[反应:见正文]不可烯化的醛和酮在碱性条件下(t-BuOK,
DMF / THF)与
2-氯乙醇和3-
氯丙醇反应,分别形成2-取代的
1,3-二氧戊环和
1,3-二氧六环。两步加成烷基化过程的转化取决于控制
氯代醇盐加成平衡的羰基的亲电子性。这种在动力学控制的条件下以环状
缩醛形式保护羰基的方法是与二醇进行酸催化反应的补充。