已经开发出一种在乙腈中使用三甲基氯硅烷/碘化钠进行碳氧键断裂的温和有效的方法。它被应用于非水和中性条件下的合成转化,如缩醛脱保护和从相应的膦酸二烷基酯通过其甲硅烷基酯的甲醇分解合成膦酸。通过 1 H NMR 在乙腈溶液中检测了各种金属碘化物或碘化铵对此类脱烷基作用的有效性。用碘化锂或碘化钾代替碘化钠也获得了令人满意的结果。然而,铜(I)或碘化季铵是无效的。乙腈中的氯三甲基硅烷/溴化锂对多功能膦酸酯或二烷基乙烯基磷酸酯的选择性脱烷基作用有效。
在含不同酸的二恶烷水溶液中研究了酸催化的2,2-二甲氧基乙基膦酸二乙酯(II)和2,2,2-二甲氧基乙基膦酸二甲酯(III)的2,2-二乙氧基乙基膦酸二乙酯(I)的水解动力学。催化剂。log k 1相对于H 0的图的斜率为0.98;(log k 1 + H 0)相对于log a H 2 O的曲线的斜率W = -0.1。化合物(II)在1 M中的氘溶剂同位素效应k D / k H-硫酸在30°为2.8。根据扎克-汉米特(Zucker-Hammett)和邦内特(Bunnett)的假设,所获得的结果与A -1机制相符。在25°下测得的二阶速率常数为:对于化合物(I),k 2 3.7×10 –4 l mol –1;对于化合物(II)和(III),k 2 3.7 ×10 –4 l mol s –1。能量(15–17 kcal mol –1)和熵(–25至–27 cal mol –1 K –1)的值较
Process for the preparation of heterosubstituted acetals
申请人:Bayer Aktiengesellschaft
公开号:US05478960A1
公开(公告)日:1995-12-26
Heterosubstituted acetals of the formula ##STR1## can be obtained by reacting vinyl compounds of the formula CH.sub.2 .dbd.CH-A.sup.1 (II) with alkyl nitrites of the formula R.sup.1 --ONO (III.) The reaction is performed in the presence of palladium in metallic or bonded form and in alcohols or ethers as reaction medium at from 0.degree. to 120.degree. C.
The invention relates to novel erythromycin derivatives, and non-toxic, pharmacologically acceptable acid addition salts thereof. The compounds as well as the salts are useful as antibacterials.