用四氟化硫处理(-)-D-酒石酸二甲酯(IVa)和(+)-L-酒石酸二甲酯(Va),得到二甲基内消旋-α,α'-二氟琥珀酸酯(Ia)。相同的试剂将中酒石酸二甲酯(IIaa)转化为D-和L-α,α'-二氟琥珀酸二甲酯(IIa)的外消旋混合物。通过假设形成环状中间体,可以合理化由氟取代羟基而在一个手性上反转构型并在另一个手性碳原子上保持构型的结果。通过随后与氟化物离子的S N 2反应,然后通过氟使硫氧基的四中心置换,将其打开。α,α'-二氟琥珀酸二甲酯Ia和IIa的各自构型由1 H和19确定通过使用旋光化学位移试剂的F NMR,并通过将酯转化为相应的酸,然后分别将其转化为顺式和反式α,α'-二氟琥珀酸酐来证实。
The formation of halogenated succinates by liquid-phase direct fluorination with elemental fluorine
作者:Robert G. Syvret、Daniel L. Vassilaros、David M. Parees、Guido P. Pez
DOI:10.1016/0022-1139(93)02975-k
日期:1994.6
Directfluorination of maleic anhydride with elemental fluorine has been investigated in different solvents at low temperatures. It was discovered that the net conversion of maleic anhydride, as well as the overall yield and composition of the halogenated products, depend strongly on the experimental conditions employed. Fluorinations conducted in fluorotrichloromethane, chloroform or mixtures thereof