A new methodology for aromatic difluoromethylation is described. Aryl iodides reacted with α-silyldifluoroacetates upon treatment with copper catalyst in DMSO or DME to give the corresponding aryldifluoroacetates in moderate to good yields. The subsequent hydrolysis of aryldifluoroacetates and KF-promoted decarboxylation afforded a variety of difluoromethyl aromatics.

Cycloaddition of difluorocarbene to alkenyl boronates 3 gave boron-substituted gem-difluorocyclopropanes 2 in stereospecific fashion. Upon treatment with lithium carbenoids, cyclopropyl boronates 2 underwent one-carbon homologation to afford a variety of gem-difluorocyclopropanes in good yields.

Cyclopropane derivatives Q 0021Boron-Substituted Difluorocyclopropanes: New Building Blocks of gem-Difluorocyclopropanes. -Cycloaddition of difluorocarbene [from (II)] to alkenyl boronates (I) and (XI) provides access towards gem-difluorocyclopropanes in a stereospecific manner. These boronates can be applied to further C-C coupling reactions like homologation [cf. (V)], homologation-oxidation [cf. (VI)], or insertion of synthetically useful structural units [cf. (VIII) and (X)]. -(FUJIOKA, Y.; AMII*, H.; Org. Lett. 10 (2008) 5, 769-772; Dep. Chem., Fac. Sci., Kobe Univ., Nada, Kobe 657, Japan; Eng.) -Mischke 31-072

A wide range of aryl iodides is coupled with silanes (I) or (IV) in the presence of CuI. Hydrolysis of the ester function according to A) followed by decarboxylation in the presence of KF or CsF produces the difluoromethyl analogues. Only in the case of (IIIg) no reaction takes place. -(FUJIKAWA, K.; FUJIOKA, Y.; KOBAYASHI, A.; AMII*, H.; Org. Lett. 13 (2011) 20, 5560-5563, http://dx.doi.org/10.1021/ol202289z ; Dep. Chem., Grad. Sch. Sci., Kobe Univ., Nada, Kobe 657, Japan; Eng.) -H. Simon 06-055