Transformable Transient Directing Group-Assisted C(sp2)-H Activation: Synthesis and Late-Stage Functionalizations of o-Alkenylanilines

The isocyanate group in aryl isocyanates serves as a trans-formable transient directing group in a Ru(II)-catalyzed ortho olefination leading to o-alkenylanilines. In alcoholic solvents, aryl isocyanates are transformed into carbamates, which initiate the insertion of acrylates via o C-H activation. In particular, tAmOH serves the dual role of solvent-cum transient directing mediator. The o-alkenylanilines are converted into azacoumarins and subsequently into C-4 aryl-substituted azacoumarins using aryl iodides as coupling partners via Pd(II)-catalyzed C-H functionalizations.

Automated summary

The isocyanate group in aryl isocyanates acts as a transformable transient directing group, leading to the ortho olefination reaction and the formation of o-alkenylanilines. In alcoholic solvents, aryl isocyanates are converted into carbamates, initiating the insertion of acrylates via ortho C-H activation. Specifically, tAmOH serves as both a solvent and a transient directing mediator. The o-alkenylanilines are further transformed into azacoumarins and C-4 aryl-substituted azacoumarins through Pd(II)-catalyzed C-H functionalizations using aryl iodides as coupling partners.