Sequential Gold‐Catalyzed Carbene Transfer/Ring Closure: Oxidative Cyclization of β‐(2‐Alkynylphenyl)‐α,β‐ynones to Indenofuranones

Abstract

Abstractβ‐(2‐Alkynylphenyl)‐α,β‐ynones undergo a gold‐catalyzed oxidative two‐fold cyclization in the presence of N‐oxides to give 1,3‐disubstituted‐8H‐indeno[1,2‐c]furan‐8‐ones in good yields. This cascade process is triggered by a selective oxygen transfer from an N‐oxide onto the gold‐activated alkynone to generate a α‐dioxocarbene intermediate which, via carbene transfer across the remaining alkyne moiety and subsequent cyclization through nucleophilic attack by a carbonyl oxygen, achieves the construction of 1,3‐disubstituted fused polycyclic furans.magnified image