The crystal structure together with unambiguous assignation of 1H and 13C NMR signals of 3-epismilagenin acetate 4 and 23-oxo-3-epismilagenin acetate 5 are described. Compound 4, crystallized as orthorhombic system a = 10.535(1) Å, b = 13.775 (1) Å, c = 18.347 (1) Å, α = β = γ = 90°; with space group P2 1 2 1 2 1 ; while compound 5 crystallized as a monoclinic system a = 10.380(1) Å, b = 7.327(1) Å, c = 17.881(1) Å, α = γ = 90°, β = 99.56(1)°, with a space group P2 1 . The presence a carbonyl group at C(23) in compound 5 produces a significant deviation from the chair conformation observed in compound 4. The effects of the side chain modifications on the puckering parameters derived from are discussed. The crystal structure, together with unambiguous assignation of 1H and 13C NMR signals of two epismilagenin acetates, is described.
本研究描述了 3-表
紫杉素乙酸酯 4 和 23-氧代-3-表
紫杉素乙酸酯 5 的晶体结构以及 1H 和 13C NMR 信号的明确分配。化合物 4 结晶为正方晶系 a = 10.535(1) Å, b = 13.775 (1) Å, c = 18.347 (1) 埃,α = β = γ = 90°;空间群为 P2 1 2 1 2 1;而化合物 5 结晶为单斜体系 a = 10。380(1) 埃,b = 7.327(1) 埃,c = 17.881(1) 埃,α = γ = 90°,β = 99.56(1)°,空间群为 P2 1。化合物 5 中 C(23)处的羰基与化合物 4 中观察到的椅状构象有明显偏差。本文讨论了侧链修饰对由此得出的起皱参数的影响。此外,还介绍了两种表米拉根碱
乙酸酯的晶体结构以及 1H 和 13C NMR 信号的明确分配。