The three-dimensional structure of the antiviral agent 5-methoxymethyl-2′-deoxycytidine (MMdCyd) was deduced by X-ray crystallographic analysis. MMdCyd crystallized in space group P21 with a = 7.9255(6) Å; b = 16.1505(15) Å, c = 10.1861(5) Å, β = 103.801(5)°, and Z = 4 (2 molecules per asymmetric unit); R = 0.044 (Rw = 0.046) for 2560 observed reflections with net I > 3σ(I). The furanose ring adopts the C(3′)-exo envelope conformation (3E) in molecule A and the C(2′)-endo envelope conformation (2E) in molecule B. In the sugar ring of both crystallographically independent molecules A and B, the side chain at C(5′) has the g+ conformation. This appears to be a preferred geometry required for antiherpes activity in 2′-deoxyribonucleosides. The glycosyl linkage is anti with χ = 213.7° for the A molecule and 222.2° for the B molecule. With respect to this anti conformation, the methoxy group at C(5) in molecules A and B exhibits different conformations; it is on the same side of the pyrimidine plane as the deoxyribofuranose ring oxygen (O4′) in molecule B and on the opposite side in molecule A. Keywords: antiherpes agent, conformation, 5-methoxymethyl-2′-deoxycytidine, crystal structure.
抗病毒药物5-甲氧甲基-2'-去氧
胞苷(MMdCyd)的三维结构通过X射线晶体学分析推导出来。MMdCyd在P2₁空间群中结晶,a = 7.9255(6) Å;b = 16.1505(15) Å,c = 10.1861(5) Å,β = 103.801(5)°,Z = 4(每个非对称单元中有2个分子);对于2560个观察到的反射,净I > 3σ(I)时,R = 0.044(Rw = 0.046)。
呋喃糖环在分子A中采用C(3')-exo信封构象(3E),在分子B中采用C(2')-endo信封构象(2E)。在两个晶体学独立分子A和B的糖环中,C(5')处的侧链呈g+构象。这似乎是2'-去氧
腺苷类抗疱疹活性所需的优选几何构型。糖基连接是反式的,A分子的χ为213.7°,B分子为222.2°。相对于这种反式构象,A和B分子中C(5)处的甲氧基呈现不同构象;在B分子中,它与去氧
核糖呋喃环氧原子(O4')位于同一侧,而在A分子中位于相反侧。关键词:抗疱疹药物,构象,5-甲氧甲基-2'-去氧
胞苷,晶体结构。