Controlled Reduction of Carboxamides to Alcohols or Amines by Zinc Hydrides

New protocols for controlled reduction of carboxamides to alcohols or amines were established using combination of sodium hydride (NaH) and zinc halides (ZnX2). Use of the different halide on ZnX2 dictates the selectivity, where the NaH‐ZnI2 system delivers alcohols and that with ZnCl2 gives amines. Extensive mechanistic studies by experimental and theoretical approaches imply that polymeric zinc hydride (ZnH2)∞ is responsible for alcohol formation, whereas dimeric zinc chloride hydride (H‐Zn‐Cl)2 is the key species for production of amines.

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