Eldrup A B, Bjergårde K, Felding J, Kehler J, Dahl O
Institute of Chemistry, H.C. Orsted Institute, University of Copenhagen, Denmark.
Nucleic Acids Res. 1994 May 25;22(10):1797-804. doi: 10.1093/nar/22.10.1797.
A method to prepare thymidine phosphorodithioate dimers (ref. 1) has been extended to allow the preparation of oligo-2'-deoxyribonucleotide phosphorodithioates containing all four bases. The method is suitable for large-scale synthesis and gives phosphorodithioates without phosphorothioate impurities (31P nmr, detection limit 0.5 to 1%). Oligonucleotides up to octamers which contain -0-(PS2-)-0- linkages at all positions have been prepared by block synthesis in solution. The phosphorodithioate linkage is introduced by the reaction of a 5'-O, N-protected nucleoside (or oligonucleotide) with a dithiophosphorylating agent RSP(S)(ODhbt)2, R = 2,4-dichlorobenzyl, Dhbt = 3,4-dihydro-4-oxo-benzotriazin-3-yl, followed by coupling of the product to a 3'-O,N-protected nucleoside (or oligonucleotide). This method gives pure protected oligodeoxyribonucleoside phosphorodithioates, and phosphorothioate linkages are only introduced if contact with conc. aqueous ammonia during or after deblocking is unduly prolonged.
一种制备胸苷二硫代磷酸酯二聚体的方法（参考文献1）已得到扩展，可用于制备包含所有四种碱基的寡聚2'-脱氧核糖核苷酸二硫代磷酸酯。该方法适用于大规模合成，且得到的二硫代磷酸酯不含硫代磷酸酯杂质（31P核磁共振，检测限为0.5%至1%）。通过溶液中的片段合成法，已制备出在所有位置均含有-0-(PS2-)-0-键的八聚体寡核苷酸。二硫代磷酸酯键是通过5'-O,N-保护的核苷（或寡核苷酸）与二硫代磷酰化试剂RSP(S)(ODhbt)2反应引入的，其中R = 2,4-二氯苄基，Dhbt = 3,4-二氢-4-氧代-苯并三嗪-3-基，然后将产物与3'-O,N-保护的核苷（或寡核苷酸）偶联。该方法可得到纯的保护型寡脱氧核糖核苷二硫代磷酸酯，且只有在脱保护过程中或之后与浓氨水的接触时间过长时，才会引入硫代磷酸酯键。
