红霉素A9-（1-异丙氧基环已基）肟的合成及其晶体结构

合成表征了红霉素A9-（1-异丙氧基环已基）肟的E和Z异构体，并在丙酮-水混 合溶液中培养出了前者的单晶，X射线衍射表明，其结构为正交晶系，P2_12_12_1 空间群，晶胞参数：a=2.3101(5) nm, b=2.3761(5) nm, c=0.97066(19)nm, V=5. 3279(8) nm~3，Z=4，μ=0.088 mm~(-1)，F(000)=2064, D_c=1.176 g/cm~3。E-红 霉素A 9-（1-异丙氧基环已基）肟的晶体结构图明显表明1-异丙氧基环已基保护基 确实使十四元大环的构象发生了扭曲，使6-OH的周围空间不再拥挤，从而导致6- OH甲基化的选择性提高。

Synthesis and Crystal Structure of Erythromycin A 9-(1-Iso- propoxycyclohexyl) oxime

E- and Z-isomers of erythromycin A 9- (l- iso -propoxycyclohexyl) oxime have been synthesized and cha-racterized. The crystal structure of E-isomer was determined by X-ray single-crystal structure analysis. The crystal belongs to orthorhombic system, Flilfa space group with a =2.3101(5) nm, b =2.3761(5) nm, c =0.97066 (19) nm, 7 = 5.3279(18) nm~3, Z = 4, μ=0.088 mm~(-1), F(000) = 2064, D_c = 1.176 g/cm~3, R_1 =0.0505, R_2 = 0.0775 for 6747 unique reflections. The torsion angles of its fourteen-member erythrolide clearly elucidated the origin of regioselectivity occurring at 6-hydroxyl in the O-methylation of erythromycin A.