A new and efficient approach to isoxazolines. First synthesis of 3-aryl-5-dichloromethyl-2-isoxazolines
作者:Antonio Guirado、Bruno Martiz、Raquel Andreu、Delia Bautista
DOI:10.1016/j.tet.2011.05.110
日期:2011.8
An efficient synthetic method for 3-aryl-5-dichloromethyl-2-isoxazolines has been established. Reactions between anhydrous chloral and acetophenones in hot acetic acid lead to 1-aryl-4,4,4-trichloro-3-hydroxybutan-1-ones (chloralacetophenones), which provided 1-aryl-4,4-dichlorobut-3-en-1-ones (2,2-dichlorovinylacetophenones) by dehydration and subsequent electrochemical reduction. These beta,gamma-unsaturated enones reacted with hydroxylamine yielding oxime intermediates whose treatment with aqueous sodium hydroxide gave novel 3-aryl-5-dichloromethyl-2-isoxazolines in fair to high yields. The molecular structure of a member of this family of compounds, 5-dichoromethyl-3-(4-methoxyphenyl)-2-isoxazoline, was determined by X-ray crystallography. (C) 2011 Elsevier Ltd. All rights reserved.