Fluoride-Triggered Synthesis of 1‑Aryl-2,2-difluoroalkenes via Desilylative Defluorination of (1-Aryl)-2,2,2-trifluoroethyl-silanes
journal contributionposted on 03.09.2021, 20:06 by Virginie Carreras, Thierry Ollevier
An efficient route for the synthesis of 1-aryl-2,2-difluoroalkenes via 1,2-desilylative defluorination is disclosed. Only a catalytic amount of fluoride source is required to initiate the desilylation and afford gem-difluoroalkenes in very good to quantitative yields, using mild reaction conditions in dimethyl carbonate as a green solvent. This reaction uses (1-aryl)-2,2,2-trifluoroethyl-silanes, which are easily prepared via the insertion reaction of trifluoroethyl diazo alkanes into the Si–H bond of tertiary organosilanes. (1-Aryl)-perfluoroalkyl-silanes cleanly afford the corresponding (Z)-1-benzylideneperfluoroalkanes, which upon hydrodefluorination furnish the (E)-β(perfluoroalkyl)styrene derivatives with excellent yield and complete stereoselectivity. A one-pot system involving sequential insertion and desilylative–defluorination is also suitable for this transformation. This method demonstrates the usefulness of organosilanes toward the preparation of fluorinated alkenes as synthetically useful targets.
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synthetically useful targetseasily prepared viadesilylative – defluorinationdifluoroalkenes via 11 ‑ arylaryl )- 2silanes cleanly afforddesilylative defluorination>- difluoroalkenes>)- 1z </tertiary organosilanesreaction usesquantitative yieldsorganosilanes towardmethod demonstratesinsertion reactiongreen solventgem </fluorinated alkenesexcellent yieldefficient routee </dimethyl carbonatecomplete stereoselectivitycatalytic amountalso suitable