A simple and effective method for stereocontrolled preparation of 1,1-diaryl-2-fluoroethenes is reported. First, 1-aryl-1-bromo-2-fluoroethenes are generated using an addition/elimination reaction of hydride to silylated beta,beta-difluorostyrene derivatives followed by a bromination/desilicobromination reaction. Subsequent Suzuki-Miyaura coupling with a variety of boronic acids gives access to the desired 1,1-diaryl-2-fluoroethenes.
Acceleration of alkenyltrimethylsilane fluorination under mild conditions using ultrasound
作者:Reza Ranjbar-Karimi
DOI:10.1016/j.ultsonch.2010.02.007
日期:2010.6
Alkenyltrimethylsilanes are selectively fluorodesilated to alkenyl fluoride very readily by reaction with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2,2,2]octane bis-tetrafluoroborate (Selectfluor) and N-fluorobenzensulfonimids at room temperature under ultrasound. In the presence of ultrasound irradiation in the case atone of the reactions, the yield was 85% after 25 min, but using the previously established thermal method the yield was only 32% after 20 h. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.
Stereoselective Synthesis of Both Stereoisomers of β-Fluorostyrene Derivatives from a Common Intermediate
stereoselective synthesis of both cis- and trans-β-fluorostyrene derivatives from a common intermediate, (Z)-1-aryl-2-fluoro-1-(trimethylsilyl)ethenes, is described. The trans isomers are obtained by a stereospecific replacement of the silyl group in the presence of water and a fluoride source, whereas the preparation of the cis isomers is achieved by a bromination/desilicobromination sequence followed