Yu Jose S, Wiemer David F
Department of Chemistry, University of Iowa, Iowa City, IA 52242-1294, USA.
J Org Chem. 2007 Aug 3;72(16):6263-5. doi: 10.1021/jo070722+. Epub 2007 Jul 13.
The Horner-Wadsworth-Emmons condensation of some alpha-phosphono lactones has been examined for conditions that impact product stereochemistry. The temperature employed to quench the reaction was found to be a major factor. For example, after the diethyl phosphonate derivative of gamma-butyrolactone was treated with potassium hexamethyldisilazane, 18-crown-6, and propionaldehyde at -78 degrees C in THF, an aliquot transferred to a flask at approximately 30 degrees C gave almost exclusively the Z-olefin product, while one allowed to warm to room temperature over several hours greatly favored the E-olefin.
已对某些α-膦酰基内酯的霍纳-沃兹沃思-埃蒙斯缩合反应进行研究，以考察影响产物立体化学的条件。结果发现，用于淬灭反应的温度是一个主要因素。例如，γ-丁内酯的二乙基膦酸酯衍生物在-78℃的四氢呋喃中用六甲基二硅氮烷钾、18-冠-6和丙醛处理后，转移至约30℃烧瓶中的一份样品几乎只得到Z-烯烃产物，而在数小时内升温至室温的一份样品则非常有利于生成E-烯烃。
