One‐Pot Synthesis of Unexplored Furo[3,2‐c]coumarin‐Pyrazine Hybrids: A Catalyst‐Free Isocyanide‐Mediated Multicomponent Annulation

We herein report an annulative isocyanide‐based multicomponent approach for the synthesis of fuzed furo[3,2‐c] coumarin‐pyrazine heterocycles. The reaction involves a one‐pot strategy employing pyrazine‐2‐aldehydes, 4‐hydroxycoumarins, and isocyanides, affording annulated oxygen‐ and nitrogen‐containing frameworks without the use of metal catalysts or additives. The transformation allows the construction of multiple heterocyclic bonds in a single operation and proceeds efficiently under mild thermal conditions. The strategy features a wide array of substrate scope, with the desired fuzed heterocycles produced in good to excellent yields. The protocol enables efficient gram‐scale synthesis with possible post‐synthetic modification of the heterocyclic core. Considering the known biological relevance of both furocoumarin and pyrazine motifs, this methodology provides a useful entry to previously unexplored fuzed heterocyclic scaffolds.