Synthesis and Structural Studies of S_P and R_P diastereomers of Deoxyxylothymidyl-3'-O-acetylthymidyl(3',5')-O-(2-Cyanoethyl)phosphorothioate in Solution and in teh Solid State

摘要

The synthesis and full assignment of the molecular structure of the diastereomers of deoxyxylothymidyl-3'-O-acetylthymedyl (3',5')-O-(2-cyanoethyl)phosphorothioate (1) in the liquid phase based on ~1H,~(13)C,1D and 2D homo- and heteronuclear PFG(Pulse Field Gradient ) NMR spectroscopic experiments are reported.The pseudorotation parameters of deoxyribose and deoxyxylose wre analyzed by emans of the PSEUROT program.The absolute configuration R_P and S_P of the phosphorus centers was deduced from ~1H ROESY experiment.The ~(31)P CP/MAS technique was used to establish the ratio between the amorphous and crystalline phases,and to test the progress of crystallization.The differences in the ~(31)P #delta#_(ii) principal elements of the chemical shift tensor,in particular the #delta#_(33) parameter,for crstalline and amorphous phases were calculated.Finally,the X-ray data for the S_P diastereomer are reported.The influence of weak C-H…S hydrogen bonding on teh molecular packing of both R_P-1 and S_P-1,and the significance of this type of intermolecular interaction for phosphorothioate systems is discussed.