No Transition Metals Required - Oxygen Promoted Synthesis of Imines from Primary Alcohols and Amines under Ambient Conditions

The synthesis of imines denotes a cornerstone in organic chemistry. The use of alcohols as renewable substituents for carbonyl-functionality represents an attractive opportunity. Consequently, carbonyl moieties can be in situ generated from alcohols upon transition-metal catalysis under inert atmosphere. Alternatively, bases can be utilized under aerobic conditions. In this context, we report the synthesis of imines from benzyl alcohols and anilines, promoted by (KOBu)-Bu-t under aerobic conditions at room temperature, in the absence of any transition-metal catalyst. A detailed investigation of the radical mechanism of the underlying reaction is presented. This reveals a complex reaction network fully supporting the experimental findings.

Automated summary

The synthesis of imines is a foundational aspect of organic chemistry. Alcohols can be used as renewable substitutes for carbonyl-functionality, allowing for the in situ generation of carbonyl moieties from alcohols using transition-metal catalysis under inert atmosphere or bases under aerobic conditions. In this study, we report the synthesis of imines from benzyl alcohols and anilines using (KOBu)-Bu-t as a catalyst under aerobic conditions at room temperature, without the need for a transition-metal catalyst. We also present a detailed investigation of the underlying radical mechanism, revealing a complex reaction network that supports the experimental findings.