| Abstract: | Dehydrogenation of ammonia borane by sterically encumbered pyridones as organocatalysts is reported. With 6‐tert‐butyl‐2‐thiopyridone as the catalyst, a turnover frequency (TOF) of 88 h?1 was achieved. Experimental mechanistic investigations, substantiated by DLPNO‐CCSD(T) computations, indicate a mechanistic scenario that commences with the protonation of a B?H bond by the mercaptopyridine form of the catalyst. The reactive intermediate formed by this initial protonation was observed by NMR spectroscopy and the molecular structure of a surrogate determined by SCXRD. An intramolecular proton transfer in this intermediate from the NH3 group to the pyridine ring with concomitant breaking of the S?B bond regenerates the thiopyridone and closes the catalytic cycle. This step can be described as an inorganic retro‐ene reaction. |
