| SYNTHESIS |
The work provides a new example of intermolecular coupling of ligand-based organometallic radicals and is reportedly the first case of spontaneous radical formation in a cobalt-alkyne system. Authors reacted propargyl alcohols with HBF4 to form salts that are stable at low temperature. When a salt is dissolved in dichloromethane and warmed to room temperature, a radical forms at the original alcohol substituent site of the compound, and radical-radical coupling leads to the dimer (shown; M = Co2(CO)6, R = H or OCH3). The dimers also can be prepared without isolating the intermediate by using triflic anhydride in place of HBF4. The results suggest that cobalt-complexed propargyl radicals should be synthetically useful to stereoselectively form "larger molecular assemblies of biological relevance."
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