The synthesis and pharmacological activities of the four stereoisomers of methyl tetrahydrofuran-2-ylmethyl 2,6-dimethyl-4-(2'-nitrophenyl)-1,4-dihydropyridine-3,5- dicarboxylate(furnidipine) are reported. The four isomers were synthesized by a modified Hantzsch synthesis by reaction of (-)- or (+)-tetrahydrofuran-2-ylmethyl 3-aminocrotonate and methyl 2-[(2'-nitrophenyl)methylene]acetoacetate or, alternatively, by reaction of (-)- or (+)-tetrahydrofuran-2-ylmethyl 2-[(2'-nitrophenyl)methylene]acetoacetate and methyl 3-aminocrotonate. The 1:1 diastereomeric mixtures thus obtained were separated by chromatography, using poly(D-phenylglycine) as the chiral stationary phase. The enantiomeric purity of the stereoisomers was determined by a high-performance liquid chromatography-chiral stationary phase technique (HPLC-CSP). Attempts to obtain crystals of a single stereoisomer failed in different solvents, while methanol crystallization of the product obtained from (+/-)-tetrahydrofuran-2-ylmethyl 2-[(2'-nitrophenyl)methylene]acetoacetate and methyl 3-aminocrotonate yielded good-quality crystals of the most insoluble racemate which proved to be a mixture of the (SS)/(RR) enantiomers by X-ray crystallography. Conformational analysis of the stereoisomers, assuming rotation of the aryl substituent and ester groups, shows small energy differences (about 4 kcal.mol-1) between the most and the least favorable conformations. Binding studies were performed using [3H]isradipine as a reference ligand. The results showed stereospecificity of the furnidipine isomers in brain, ileum, and cardiac tissues, the (SS)- and (SR)-isomers clearly being more potent than their (RR)- and (RS)-enantiomers. The (SS)- and (SR)-isomers were also more selective on cerebral tissue when compared with ileal and cardiac preparations.

中文翻译：

---

呋尼地平立体异构体的合成，结构和药理评价。

报道了甲基四氢呋喃-2-基甲基2,6-二甲基-4-（2'-硝基苯基）-1,4-二氢吡啶-3,5-二羧酸酯（呋喃地平）的四种立体异构体的合成和药理活性。通过改进的Hantzsch合成，通过（-）-或（+）-四氢呋喃-2-基甲基3-氨基巴豆酸酯与2-[（（2'-硝基苯基）亚甲基]乙酰乙酸甲酯]的反应，合成四种异构体（-）-或（+）-四氢呋喃-2-基甲基2-[（（2'-硝基苯基）亚甲基]乙酰乙酸酯和3-氨基巴豆酸甲酯。用聚（D-苯基甘氨酸）作为手性固定相，通过色谱法分离得到的1∶1非对映异构混合物。通过高效液相色谱-手性固定相技术（HPLC-CSP）测定立体异构体的对映体纯度。尝试在不同溶剂中获得单一立体异构体的晶体失败，而由（+/-）-四氢呋喃-2-基甲基2-[（（2'-硝基苯基）亚甲基]乙酰乙酸酯和3-氨基巴豆酸甲酯获得的产物的甲醇结晶高质量的最不溶外消旋体晶体，通过X射线晶体学证明是（SS）/（RR）对映异构体的混合物。假设芳基取代基和酯基团旋转，对立体异构体的构象分析表明，在最有利和最不利构象之间的能量差较小（约4 kcal.mol-1）。使用[3H]异拉地平作为参考配体进行结合研究。结果显示呋喃地平异构体在脑，回肠和心脏组织中的立体特异性，（SS）-和（SR）-异构体显然比它们的（RR）-和（RS）-对映体更有效。与回肠和心脏制剂相比，（SS）和（SR）异构体在脑组织上的选择性也更高。