Isocyanide‐Based Three‐Component Reaction for Construction of Spiro and Fused Furan Frameworks

A practical synthetic protocol for diverse spiro and fused furan frameworks was developed by isocyanide‐based three‐component reactions. The three‐component reaction of alkyl isocyanides, dialkyl but‐2‐ynedioates, and 3‐( o ‐hydroxyphenacylidene)oxindoles or 2‐(indol‐3‐yl)indene‐1,3‐diones afforded special spiro[benzofuran‐3,2′‐furans] and indeno[2,1‐ b ]oxeto[2,3‐ c ]furans in good yields and with high diastereoselectivity. The single crystal structure determination showed that the unique polycyclic compounds with spiro and fused furan frameworks were efficiently formed.