Gold-Catalyzed Regioselective Oxyfluorination/Oxydifluorination vs. Diketonization of Phthalimido-Protected Propargylamines with Selectfluor

Alkyl- and aryl-substituted N-propargyl phthalimides were used as valuable building blocks for the selective formation of the corresponding alpha-fluoro, beta-phthalimido ketones, alpha,alpha-difluoro, beta-phthalimido ketones or beta-phthalimido alpha-diketones by means of gold-catalyzed oxyfluorination/oxydifluorination or dioxygenation reactions. The key factors addressing the product selectivity control were determined. The simultaneous assembly of the quinoxaline nucleus and the removal of the phthalimido-protecting group were tested. Reaction mechanisms of the different reaction pathways are assumed.

Automated summary

In this study, alkyl- and aryl-substituted N-propargyl phthalimides were used as starting materials to selectively synthesize α-fluoro, β-phthalimido ketones, α,alpha-difluoro, β-phthalimido ketones, or β-phthalimido α-diketones through gold-catalyzed oxyfluorination/oxydifluorination or dioxygenation reactions. Key factors controlling product selectivity were identified, and the simultaneous assembly of the quinoxaline nucleus and removal of the phthalimido-protecting group were tested. Hypothetical reaction mechanisms for different reaction pathways were proposed.