1-(Trifluoromethyl)vinylation via Oxirane or Oxetane Ring-Opening: A Facile Synthesis of 4- or 5-Hydroxy-Functionalized 2-Trifluoromethyl-1-alkenes

Abstract

Introduction of a 1-(trifluoromethyl)vinyl group has been accomplished by the reaction of thermally unstable 1-(trifluoromethyl)vinyllithium (1) with strained cyclic ethers. Treatment of 2-bromo-3,3,3-trifluoropropene with butyllithium generates 1, which in turn reacts with several oxiranes or an oxetane at -100 °C in the presence of BF₃·OEt₂ to afford the corresponding 2-trifluoromethyl-1-alkenes bearing a hydroxy group on the 4- or 5-position. An enantiopure oxirane undergoes ring-opening without racemization, providing an optically active homoallyllic alcohol with a 3-trifluoromethyl group.

(trifluoromethyl)vinyl group - ring-opening - oxirane - unsaturated alcohol - lithium-halogen exchange

References

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