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Application of this method is demonstrated by the first total synthesis of Reticuol (VIII).

3-Formylfuran derivatives are core structures of a variety of bioactive natural products. However, procedures for their preparation are still rare and generally inefficient in terms of atom economy: These methods require multiple steps or harsh reaction conditions and show selectivity problems. An efficient gold(I)-catalyzed cascade reaction that leads to 3-formylfurans from easily accessible starting materials is now described. A wide variety of 3-formylfurans were obtained from the corresponding symmetric and unsymmetric 1,4-diyn-3-ols in the presence of an N-oxide in good to excellent yields. Isotope-labeling experiments as well as DFT calculations support a mechanism in which, after an initial oxygen transfer, a 1,2-alkynyl migration is favored over a hydride shift; a cyclization ensues to afford the desired functionalized furan core.

The title synthesis starts from simple, easily available urea-substituted 3-phenylpropargyl alcohols.

A wide range of highly substituted cyclopentadienes can be synthesized under mild reaction conditions and with complete atom economy.