Exploiting the Reactivity of 2-Diazo-1,1,3,3,3-Pentafluoropropyl Phosphonate in [2,3]-Sigmatropic Rearrangement Reactions

The Cu(II)-catalysed [2,3]-sigmatropic rearrangement of allyl and propargyl sulfides with the fluorinated diazo compound, 2-diazo-1,1,3,3,3-pentafluoropropyl phosphonate, has been investigated experimentally and computationally.The corresponding products 2 and 3a-d were obtained in yields of up to 79 %.Kinetic studies and DFT calculations indicate that Cu(I), generated in situ by reduction of Cu(II) with the diazo substrate, is the catalytically active species.The reaction proceeds via formation of a copper carbene and sulfonium ylide, which undergoes a facile [2,3]-sigmatropic rearrangement.These results expand the synthetic utility of fluorinated diazo compounds and provide mechanistic insight into the Doyle-Kirmse reaction under copper catalysis.