作者:Manish Kumar、Vivek K. Sharma、Carl E. Olsen、Ashok K. Prasad
DOI:10.1039/c4ra06805j
日期:——
Conformationally locked 3â²-azido-3â²-deoxythymidine analogues of T, U, A and C containing a 2â²-O,4â²-C-methylene linked bicyclic furanose moiety has been efficiently synthesized following a greener chemo-enzymatic convergent route. Thus, one of the two diastereotopic hydroxyl groups of 3-azido-3-deoxy-4-C-hydroxymethyl-1,2-O-isopropylidene-α-D-ribofuranose has been regioselectively acetylated using Novozyme®-435 in quantitative yield. The selective enzymatic acetylation can be carried out with the same efficiency using Novozyme®-435 for 10 cycles of reaction. The monoacetylated sugar derivative was converted to bicyclic 3â²-azidonucleosides in four steps in overall yields of 60 to 68%. It has been demonstrated that 3â²-azido-3â²-deoxy-2â²-O,4â²-C-methylenethymidine can easily be converted into 3â²-amino-3â²-deoxy-2â²-O,4â²-C-methylenethymidine in 95% yield, which is an important monomer for the synthesis of therapeutically useful sugar-modified oligonucleotides.
顺式锁定的3′-叠氮-3′-脱氧胸苷类似物,含有2′-O, 4′-C-亚甲基连结的双环呋喃糖部分,已通过一种更绿色的化学-酶促收敛路线高效合成。因此,3-叠氮-3-脱氧-4-C-羟甲基-1,2-O-异丙基腈-α-D-核糖的两个非对映体羟基中的一个已使用Novozyme®-435进行区域选择性乙酰化,量产率达到定量。选择性的酶促乙酰化在10次反应循环中使用Novozyme®-435也能以相同的效率进行。单乙酰化的糖衍生物在四个步骤中转化为双环3′-叠氮核苷,整体产率为60%到68%。已证明3′-叠氮-3′-脱氧-2′-O, 4′-C-亚甲基胸苷可以轻松转化为3′-氨基-3′-脱氧-2′-O, 4′-C-亚甲基胸苷,产率为95%,这是一种合成具有治疗用途的糖修饰寡核苷酸的重要单体。