In situ generated aminodiborane as a reagent for deoxygenative reduction of carboxamides to amines

Herein, we report a new method for the synthesis of aminodiborane (mu-NH2B2H5) by the reaction of NH3BH3 and elemental iodine (I-2). The in situ generated aminodiborane is used as a reagent for the reduction of carboxamides to amines. This method is applicable to obtain various secondary amides, tertiary amides, and trifluoroamides, with yields in the range of 67-94%. This protocol is also useful for preparing galipinine, cinacalcet and tetracaine hydrochloride, which are pharmaceutically important compounds. Control experiments and DFT studies have been carried out to explore the mechanistic pathway. These studies indicate that the active reagent in the reduction of secondary amides is aminodiborane and in the case of tertiary amides, aminodiborane and polyaminoborane.

Automated summary

In this study, a new method for synthesizing aminodiborane is reported and applied for the reduction of carboxamides. The method allows the synthesis of various amides with high yields and is also useful for preparing important pharmaceutical compounds. Control experiments and DFT studies have provided insights into the mechanistic pathway of this reaction.