A series of pharmaceutically relevant small molecules and biopharmaceuticals bearing aliphatic carboxamides have been successfully labeled with carbon-13. Key to the success of this novel carbon isotope labeling technique is the observation that C-labeled Ni -acyl complexes, formed from a CO insertion step with Ni -alkyl intermediates, rapidly react in less than one minute with 2,2'-dipyridyl disulfide to quantitatively form the corresponding 2-pyridyl thioesters. Either the use of C-SilaCOgen or C-COgen allows for the stoichiometric addition of isotopically labeled carbon monoxide.
View Article and Find Full Text PDF