Catalytic Cycloisomerization of Enyne Diesters Derived From 2‐Propargyloxyarylaldehydes

Abstract A catalytic cycloisomerization of enyne diesters derived from 2‐propargyloxyarylaldehydes is described. The cycloisomerization, catalyzed by 10 mol% In(OTf) 3 , provides access to 2 H ‐chromenes bearing diethyl 2‐(hetero)arylidene malonates at 3‐position. This enyne metathesis‐type reaction is also useful for the synthesis of thia‐, aza‐ and quinoline analogs of the 3‐substituted 2 H ‐chromenes. DDQ mediated oxidative C−N bond formation and further synthetic manipulation enables the conversion of 3‐substituted 2 H ‐chromene into chromene‐fused molecular scaffold. Pd(0)‐catalyzed intramolecular Heck reaction on suitably substituted 2 H ‐chromene provides indene‐based molecular scaffold. magnified image