An Efficient Synthesis of Difluoropropargyl Bromides

Abstract

High yields of γ-alkyl, -silyl and -aryl-substituted difluo­ropropargyl bromides have been obtained by monitoring concentration and temperature in the reaction between CF₂Br₂ and γ-substituted lithium acetylide. γ-Silyl substituents afforded the corresponding α,α,α-difluorobromopropargyl alcohols in good yields via cleavage of tetrabutylammonium fluoride in the presence of an aldehyde.

Key words

alkynylation - fluorine - building block - substituent effect

References

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1

New address: Sumitomo Chemical Ltd. 4-2-1, Takatsukasa, Takarazuka, Hyogo 665-8555, Japan.

14

Percy and coworkers found that pre-cooling dibromo­-difluoromethane to -78 °C before addition to the lithioalkyne allowed 2c to be isolated in 85% yield after distillation on a 0.25 mol scale; see ref. 11.