A Method for Synthesis of Fluorine Compounds Using Abnormal Grignard Reaction of Halothane. II. Reaction with Aldehydes and Unsaturated Ketones.
作者:Toshiyuki TAKAGI、Atsushi TAKESUE、Akiharu ISOWAKI、Mayumi KOYAMA、Akira ANDO、Itsumaro KUMADAKI
DOI:10.1248/cpb.43.1071
日期:——
In an abnormal Grignard reaction of halothane, the primary Grignard reagent reacts with another mole of halothane to give 1-bromo-1-chloro-2, 2, 2-trifluoroethylmagnesium bromide, which in turn reacts with a carbonyl compound to give 1-bromo-1-chloro-2, 2, 2-trifluoroethyl carbinols and their dehalogenation products, 1-chloro-2, 2-difluoroethenyl carbinols. We examined the application of this method to aldehydes and to unsaturated ketones. Aldehydes were much less reactive than ketones, and needed higher reaction temperature. However, elevation of temperature caused dehalogenation of the primary products to 1-chloro-2, 2-difluoroethenyl derivatives. These derivatives were treated with hydrogen fluoride to afford 1-chloro-1-(trifluoromethyl)ethene derivatives. The reaction of α, β-unsaturated ketones mainly gave 1, 2-addition products of the Grignard reagent, while 3-methyl-2-cyclohexenone gave mainly the 1, 4-adducts.
在卤代甲烷的格氏反常反应中,主格氏试剂与另一摩尔的卤代甲烷反应生成 1-溴-1-氯-2, 2, 2-三氟乙基溴化镁,溴化镁又与羰基化合物反应生成 1-溴-1-氯-2, 2, 2-三氟乙基甲醇及其脱卤产物 1-氯-2, 2-二氟乙烯基甲醇。我们研究了这种方法在醛类和不饱和酮类中的应用。醛的反应性比酮低得多,需要更高的反应温度。然而,温度升高会导致初级产品脱卤,生成 1-氯-2,2-二氟乙烯基衍生物。这些衍生物经氟化氢处理后得到 1-氯-1-(三氟甲基)乙烯衍生物。α、β-不饱和酮的反应主要得到格氏试剂的 1、2-加成产物,而 3-甲基-2-环己烯酮则主要得到 1、4-加成产物。