(o-Hydroxyphenyl)methylphosphonic acids are readily obtained from o-(bromomethyl)- or o-(hydroxymethyl)phenols and trialkyl phosphites. Subsequent hydrolysis leads to the corresponding phosphonic acids. For a series of such compounds, the pKavalues have been determined by potentiometry. Their dependence on additional substituents in the aromatic ring is discussed in terms of electronic and steric
从邻-(溴甲基)-或邻-(羟甲基)酚和亚磷酸三烷基酯容易获得(邻-羟基苯基)甲基膦酸。随后的水解产生相应的膦酸。对于一系列此类化合物,p K a值已通过电位计确定。根据电子和空间效应,讨论了它们对芳环中其他取代基的依赖性。
Synthesis and molecular structure of new phosphorous-crown compounds containing the thiophosphoryl group
作者:Jean-Paul Declercq、Pascale Delangle、Jean-Pierre Dutasta、Luc Van Oostenryck、Pascal Simon、Bernard Tinant
DOI:10.1039/p29960002471
日期:——
The synthesis and characterization of four phosphorus macrocycles (1–4) are reported. The X-ray crystal structures of compounds 1–4 and solvate 1·H2O show the molecules in asymmetric conformations with at least one methyl group of the phenoxy substituents oriented toward the centre of the macrocyclic cavity. Variable-temperature 1H NMR experiments show that in solution the molecules exist mainly as rapidly interconverting conformers. In the 18-membered ring 1, the dynamic process results in the enantiomerization of asymmetric conformers with a barrier of 8 kcal mol–1.‡ The 21-membered ring 3 is more flexible and exists in several conformations.