Conformational analysis of cyclic phosphates derived from 5-C′ substituted 1,2-O-isopropylidene-α-d-xylofuranose derivatives
作者:Fernando Sartillo-Piscil、Silvano Cruz、Mario Sánchez、Herbert Höpfl、Cecilia Anaya de Parrodi、Leticia Quintero
DOI:10.1016/s0040-4020(03)00582-9
日期:2003.6
equilibria were observed in solution. We observed that the strong anisotropic shielding effect of the benzene ring in the phenoxy group generates an upfield shift of the H1 hydrogen atom, when the cyclic phosphates adopt a boat conformation. This is due to a relative cis-orientation of the P-phenoxy group and the H1 proton of the 1,2-O-isopropylidene-α-d-xylofuranose moiety. Therefore, the configuration
从以下两个步骤制备十二个2-苯氧基-2-氧代-1,3,2-二氧杂磷酰氨基醚与1,2 - O-异亚丙基-α-d-木呋喃糖部分以顺式方向融合并在C'5位置取代的位置市售的双丙酮-α-d-葡萄糖。它们的构象和构型是通过1 H和31 P NMR和X射线晶体学技术确定的。溶液中均观察到了椅子扭曲的椅子和椅子与小船的平衡。我们观察到,当环状磷酸酯采用舟型构象时,苯氧基中苯环的强各向异性屏蔽作用会产生H 1氢原子的高场移位。这是由于相对顺式1,2 - O-异亚丙基-α-d-木呋喃糖部分的P-苯氧基和H 1质子的-取向。因此,磷中心(S P或R P)的构型可以通过1 H NMR谱确定。有趣的是,一种环状磷酸酯的晶体结构在不对称单元中表现出两个独立的分子,一个带有椅子,另一个带有船形。