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Relevant academic research and scientific papers

An efficient synthesis of difluoropropargyl bromides

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. Georg Thieme Verlag Stuttgart.

Highly regioselective synthesis of gem-difluoroallenes through magnesium organocuprate SN2′ substitution

The reaction of gem-difluoropropargyl electrophiles with Grignard reagents is complicated by the inherent difficulty of executing nucleophilic substitutions on a CF2 group, and the facile formation of carbenoid intermediates arising from α-elimination of fluoride. In the presence of an excess amount of a copper salt, a Grignard reagent reacts with gem-difluoropropargyl bromide via an SN2′ mechanism to produce gem-difluoroallene in high yield. If desired, the resulting difluoroallene can undergo a second nucleophilic attack on the CF2 terminus to yield a trisubstituted monofluoroallene through an addition-elimination mechanism.

Nucleophilic and electrophilic substitutions of difluoropropargyl bromides

Fundamental organic reactions like nucleophilic and electrophilic substitutions have seldom been studied on fluorinated propargyl or allenyl modules, when the carbon atom undergoing substitution is bonded to two fluorine atoms. Herein we report a practical synthesis of difluoropropargyl bromides from substituted acetylenes and dibromodifluorometane using a wide variety of alkyl, aryl or silyl substrates. The synthesis of O-, S- and carboxylic acid derivatives of difluoropropargyl bromide is also described. These compounds are suitable starting materials for the synthesis of electrophilically substituted difluoropropargyl derivatives via magnesium and fluoride promoted reactions. An indium-mediated reaction of silyldifluoropropargyl bromide, followed by electrophilic trapping with bromine led to a very useful bromoallene, which was then used in reactions with nucleophiles (C, O, N, P, S, Hal) to yield a de facto bimolecular nucleophilic substitution of a difluoropropargyl bromide.

Crystallographic characterization of difluoropropargyl indium bromide, a reactive fluoroorganometallic reagent

Elusive intermediate trapped: γ-Substituted difluoropropargyl groups can stabilize an organoindium(III) complex. The resulting structure is the only known example of an indium atom bonded to a propargylic carbon atom (see picture; F blue, S yellow, C white, H green). Reactions with electrophiles produced a difluoroalkyne or -allene, depending on the type of electrophile. (Chemical Equation Presented).