A new, non‐symmetrical copper(II) pincercomplex catalyzes much more efficiently the formation of benzofuran by the reaction between ortho‐iodophenols and alkynes. The lowest catalyst loadings are realized for this reaction, and bromo‐ and chlorophenols are heteroannulated for the first time. Strong evidence for hydrophenoxylation and intramolecular halogen atom‐transfer steps catalyzed by this remarkably
AbstractEthyl acetohydroxamate was efficiently arylated with diaryliodonium salts at room temperature under transition‐metal‐free conditions. The obtained O‐arylated products were reacted in situ with ketones under acidic conditions to yield substituted benzo[b]furans through oxime formation, [3,3]‐rearrangement, and cyclization in a fast and operationally simple one‐pot fashion without using excess reagents. Alternatively, the O‐arylated products could be isolated or transformed in situ to aryloxyamines or O‐arylaldoximes. The methodology was applied to the synthesis of Stemofuran A and the formal syntheses of Coumestan, Eupomatenoid 6, and (+)‐machaeriol B.