Reductive Cleavage of Allyllic Ketals by an Arene-Catalysed Lithiation: A Simple and Direct Route to Masked Lithium Homoenolates
作者:Juan F Gil、Diego J Ramón、Miguel Yus
DOI:10.1016/s0040-4020(01)87023-x
日期:1994.3
The reaction of acrolein diethyl acetal 1 with an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB; 2.5 mol %) in the presence of a carbonyl compound 2 in THF at 0°C leads, after hydrolysis with water, to the corresponding γ-coupling products 3 as a Z/E mixture, the Z-isomer being mainly the major one. When the final hydrolysis was carried out in acidic conditions
丙烯醛二乙缩醛1与过量的锂粉和催化量的4,4'-二叔丁基联苯(DTBB; 2.5 mol%)在羰基化合物2在THF中的存在下于0°C反应,用水水解成相应的γ-偶联产物后3作为Z / E混合物中,ž -异构体是主要的主要之一。当最终水解在酸性条件(3 N盐酸)下进行,然后在三氟化硼醚化物存在下于二氯甲烷中于-78至20°C的温度下,用R 3 SiNu型硅化合物处理,相应的取代的四氢呋喃4获得了。酸水解后,将相同的Barbier型反应应用于2-环戊烯酮乙烯缩酮5,可产生预期的3-取代的环戊酮6。在所有情况下,总产量都是中等水平。