Microwave assisted Diels-Alder cycloaddition of 2-fluoro-3-methoxy-1,3-butadiene
摘要:
The title fluorodiene (2) reacts with several dienophiles in moderate yields (20-65%, 0.5 h to 3d) when thermal activation is used. When 100 W microwave radiation is used the reaction yields (70-90%, 5-25 min) are greatly improved and the reaction times are much shorter. A microwave procedure is also used for the hydrolysis of vinyl ether cycloadducts to alpha-fluoroketones. (c) 2007 Elsevier B.V. All rights reserved.
A Convenient Preparation of 2-Fluoro-3-alkoxy-1,3-butadienes
摘要:
[GRAPHICS]1-Chloro-1-fluoro-2-methoxy-2-methylcyclopropane eliminates HCl on heating in quinoline solution above 50 degreesC to give 2-fluoro-3-methoxy-1,3-butadiene in high yield. If an alcohol is added to the reaction then a 2-fluoro-3-alkoxy-1,3-butadiene is obtained in high yield. The dienes give smooth 4 + 2 cycloaddition reactions.