Synthesis of Complex Diarylamines through a Ring-Opening Difunctionalization Strategy

The diarylation and skeletal diversification of unstrained cyclic amines was exploited to expand and modify the favorable properties of this important substrate class with pivotal roles in drug discovery. Cyclic amines were employed in the synthesis of a novel class of amino-substituted diaryliodonium salts, which were converted to highly functionalized diarylamines through an atom-efficient one-pot N-arylation/ring opening reaction with external nucleophiles. The reaction proceeds through in situ formation of a diarylammonium intermediate that undergoes a nucleophilic ring opening by cleavage of the strong C-N bond. A wide variety of diarylamines was obtained through introduction of two different aryl groups of varied electronics, and the retained iodo-substituent enables downfield diversifications of the products. More than 20 nucleophiles, including amines, phenols, carboxylic acids, thiols and halides, were alkylated with high functional group tolerance, and the strategy proved efficient also in in late-stage functionalization of natural products and pharmaceuticals. Novel amino-functionalized diaryliodonium salts were obtained through SNAr with o-fluoro-diaryliodonium salts. A sequential arylation/ring opening pathway with external nucleophiles allows for transition metal-free skeletal diversification of cyclic amines to provide a wide variety of complex diarylamines with high atom- and step-economy. The strategy proved efficient also in late-stage functionalization of natural products and pharmaceuticals.**image

Automated summary

The diarylation and skeletal diversification of unstrained cyclic amines was explored to expand and modify their properties. A novel class of amino-substituted diaryliodonium salts was synthesized from cyclic amines and converted to highly functionalized diarylamines through a one-pot N-arylation/ring opening reaction. This strategy proved efficient in the late-stage functionalization of natural products and pharmaceuticals, and provided a wide variety of complex diarylamines. The method involves the introduction of two different aryl groups and the retention of an iodo-substituent, allowing for downfield diversification of the products.