Attempts were made to improve the synthesis of methyl 2, 6-dimethyl-4-(2-nitrophenyl)-5-(2-oxo-1, 3, 2-dioxaphosphorinan-2-yl)-1, 4-dihydropyridine-3-carboxylate (DHP-218), a new calcium antagonist. 2-Acetonyl-2-oxo-1, 3, 2-dioxaphosphosphorinane (5a), the key intermediate, was prepared from the allenylphosphonate (2) via the enaminophosphonate (4) in a good yield. Subsequently, the Knoevenagel condensation using 5a and the imine (6a) gave the benzylideneacetonylphosphonate (7a) in a good yield without the use of the Horner-Emons reaction. This condensation also gave good results for other acetonylphopshonates. The final step gave DHP-218 in a good yield through a modified Hantzsch synthesis with the use of a dehydrating agent. The overall yield was increased from 1.7% to 22%.
尝试改进甲基2,6-二甲基-4-(2-
硝基苯基)-5-(2-氧代-1,3,2-二氧杂
磷-2-基)-1,4-
二氢吡啶-3的合成-
羧酸盐(
DHP-218),一种新型
钙拮抗剂。关键中间体2-
丙酮基-2-氧代-1,3,2-二氧杂
磷膦烷(5a)是由
丙二烯基
膦酸酯(2)经由烯
氨基膦酸酯(4)以良好的收率制备的。随后,使用5a和
亚胺(6a)进行Knoevenagel缩合,在不使用Horner-Emons反应的情况下以良好的收率得到亚
苄基丙酮基
膦酸酯(7a)。这种缩合对于其他乙酰基
磷酸酯也给出了良好的结果。最后一步通过使用脱
水剂的改进的 Hantzsch 合成以良好的收率得到了
DHP-218。总收益率从1.7%提高到22%。