The synthesis of several cyclic dialkoxy orthoesters is reported. Acid hydrolysis of these orthoesters under kinetically controlled conditions gives the corresponding hydroxy esters only. Conformationally rigid cyclic mixed orthoesters give a hydroxy ester by exclusive loss of the axial alkoxy group. A cyclic orthoester can have nine different gauche conformations. It is shown that they are hydrolyzed
报道了几种环状二烷氧基原酸酯的合成。这些原酸酯在动力学控制条件下的酸
水解仅产生相应的羟基酯。构象刚性环状混合原酸酯通过仅失去轴向烷氧基而得到羟基酯。环状原酸酯可以有九种不同的gauche构象。结果表明,它们仅通过一种 gauche 构象异构体
水解。这些结果带来了进一步的实验证据,表明
酯类水解中四面体中间体的裂解存在立体电子控制。