Treatment of (dicarbonylmethylene)triphenylphosphoranes 1 with [(diethoxylphosphinoyl)methyl]lithium (2a) gave 3a, followed by protonation and elimination of triphenylphosphine oxide, to afford the Z-isomer exclusively (4b, 4e, 4f, 4g); while [(dialkoxyphosphinoyl)alkyl]lithium (2b) reacted with 1 under the same conditions, to give the E-isomers exclusively (4a, 4c, 4d) or predominantly (4h, 4i, 4j). Thus this methodology provides a stereocontrolled synthesis of the title compounds.
用[(二乙
氧基膦酰基)
甲基]
锂(2a)处理(双羰
甲基)
三苯基膦1,得到3a,随后进行质子化和
三苯基膦氧化物的消除,得到单一的Z型异构体(4b, 4e, 4f, 4g);而[(二烷
氧基膦酰基)烷基]
锂(2b)在相同条件下与1反应,得到单一的E型异构体(4a, 4c, 4d)或主要是E型异构体(4h, 4i, 4j)。因此,这种方法提供了立体控制合成标题化合物的方法。