Rhenium-Promoted C-C Bond-Cleavage Reactions of Internal Propargyl Alcohols

The first examples of C-C bond cleavage reactions of internal propargyl alcohols to give vinylidene complexes are described. Treatment of [Re(dppm)(3)]I with RC CC(OH)R'R'' (R = aryl, alkyl; C(OH)R'R'' = C(OH)Ph-2,Ph- C(OH)Me-2, C(OH)HPh, C(OH)H-2) produced the vinylidene complexes ReI(=C=CHR)(dppm)(2) with the elimination of C(O)R'R''. Computational studies support that the reactions proceed through a beta-alkynyl elimination of alkoxide intermediates Re{OC(R')(R'')C CR}(dppm)(2).