Abstract The reactions of t-BuLi, sec-BuLi and n-BuLi with CO in the presence of isothiocyanates and isocyanates gives, after hydrolytic work-up, α-oxothioamides, RC (O) C (S) NHR′, and α-oxoamides, RC (O) C (O) NHR′, respectively, in good yield. Competition