Indolization of N-Aryl Tertiary Amines with Diazoacetates by a Single Organophotocatalyst

Diazoacetates are widely used tosynthesize highly valuableindoles.Previous research has focused on using metal carbene reactivity orthe innate nucleophilicity of the diazoacetates to create indolesthrough a traditional two-electron pathway. However, these strategiesare constrained by the need for transition metals, oxidants, or substrateprefunctionalization. To overcome the limitations, we report hereinan open-shell strategy that utilizes the radical reactivity of diazoacetatesto synthesize indoles for the first time, especially for more valuable[a]-annulated indoles. Notably, this visible-light-driventransformation is enabled by a single organophotocatalyst, proceedingwithout metals ot additives. Preliminary mechanistic studies and densityfunctional theory calculations disclose a relay visible-light photoredoxcatalytic process that probably involves several discrete photoredoxcatalytic cycles in a single operation with one organophotocatalyst.

Automated summary

By utilizing the radical reactivity of neutral diazoacetates, we have developed a method for synthesizing indole compounds, especially valuable [a]-annulated indoles, without the need for transition metals, oxidants, or substrate prefunctionalization. This visible-light-driven transformation is enabled by a single organophotocatalyst, without the use of metals or additives.