Deoxygenation of 1° and 2° Amides with Ce[N(SiMe3)2]3(THF)3 under Mild Conditions

Abstract

The development of sustainable methods for the synthesis of amines using commercially available/easy-to-synthesize catalysts under mild conditions is one of the current interests in catalysis. A method of amide-to-amine reduction that is convenient, mild, and easy to implement is a long sought after goal from the catalysis viewpoint. In this work, we have utilized easily accessible Ce[N(SiMe3)2]3(THF)3 as a catalyst for the hydroboration of 1° and 2° amides under mild conditions, which affords corresponding amines in very good yields. It is important to mention that 1° amides are the most difficult to reduce and usually require high temperatures. Further, this methodology is also implemented for the synthesis of indole derivatives and a gram-scale reaction, thereby displaying the broad applicability of Ce[N(SiMe3)2]3(THF)3 as a catalyst. A detailed experimental study is performed to understand the mechanistic aspects of the Ce[N(SiMe3)2]3(THF)3-catalyzed amide hydroboration reaction, which reveals that the formation of an amidate complex is vital for the catalytic cycle.