First synthesis of 3-aryl-5-dichloromethyl-2-pyrazolines. The electrochemical generation of 2,2-dichlorovinylacetophenones as a key step
作者:Antonio Guirado、Bruno Martiz、Raquel Andreu
DOI:10.1016/j.tetlet.2004.09.101
日期:2004.11
intermediates 2 under acidic conditions yielded 2,2,2-trichloroethylideneacetophenones 3, which were transformed to 2,2-dichlorovinylacetophenones 5 in nearly quantitative yields by selective electrochemical monodechlorination at either mercury or graphite electrodes. Finally, 3-aryl-5-dichloromethyl-2-pyrazolines 7 were efficiently obtained on treatment of compounds 5 with either hydrazine or methylhydrazine
The firstmethod for the synthesis of 1-aryl-4,4-dichlorobut-3-en-1-ones is reported. Treatment of acetophenones with anhydrous chloral leads to 1-aryl-4,4,4-trichloro-3-hydroxybutan-1-ones in near quantitative yields. These compounds were efficiently dehydrated with either sulfuric or p-toluenesulfonic acid to give 1-aryl-4,4,4-trichlorobut-2-en-1-ones, which were selectively converted to the title
Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid
作者:Vladislav A Sokolov、Andrei A Golushko、Irina A Boyarskaya、Aleksander V Vasilyev
DOI:10.3762/bjoc.19.105
日期:——
(CCl3-indanones) in Brønsted superacid CF3SO3H (triflic acid, TfOH) at 80 °C within 2–10 h in yields up to 92%. Protonation of the carbonyl oxygen of the starting CCl3-enones by TfOH affords the key reactive intermediates, the O-protonated forms ArC(=OH+)CH=CHCCl3, which are then cyclized into the target CCl3-indanones. These cations have been studied experimentally by means of NMR spectroscopy in TfOH and