Horner–Emmons Olefination of 4-Hydroxy-2-oxoalkylphosphonates and Related Compounds: Applications to the Syntheses of (±)-Gingerol, (±)-Yashabushiketol, and (±)-Dihydroyashabushiketol
作者:Otohiko Tsuge、Shuji Kanemasa、Norihiko Nakagawa、Hiroyuki Suga
DOI:10.1246/bcsj.60.4091
日期:1987.11
Horner–Emmons olefination of 4-hydroxy-2-oxoalkylphosphonates, readily available by hydrogenation of 5-substituted 3-phosphinylmethyl-2-isoxazolines, gives mainly E-isomers of 1-hydroxy-4-alken-3-ones bearing a variety of substituents at the 1-position. Use of the combination of triethylamine (or DBU)+lithium bromide as a weak base on the O-unprotected phosphonates is favored. Similar olefinations on the isoxazolines, 2-oxo-3-alkenylphosphonates, and 4-alkoxy-2-oxoalkylphosphonates have been also examined. Their synthetic applications to (±)-Gingerol, (±)-Yashabushiketol, and (±)-Dihydroyashabushiketol are described.
4- 羟基-2-氧代烷基膦酸盐的 Horner-Emmons 烯化反应可通过 5-取代的 3-膦酰甲基-2-异噁唑啉的氢化反应轻易获得,主要得到 1-羟基-4-烯-3-酮的 E-异构体,这些异构体在 1-位上带有各种取代基。使用三乙胺(或 DBU)+溴化锂组合作为弱碱对 O 型未受保护的膦酸盐进行反应是有利的。此外,还研究了异噁唑啉、2-氧代-3-烯基膦酸盐和 4-烷氧基-2-氧代烷基膦酸盐的类似烯化作用。介绍了它们在 (±)-Gingerol, (±)-Yashabushiketol 和 (±)-Dihydroyashabushiketol 中的合成应用。