Abstract
The intramolecular gold(I)-catalyzed [2+2+2] cycloaddition of oxo-1,5-enynes bearing protected homopropargylic alcohols provides access to oxatricyclic adducts with good to excellent diastereoselectivity.
Highlights
The cycloisomerization of 1,n-enynes catalyzed by gold(I) and other electrophilic metals is a powerful tool for the construction of complex carbocycles and heterocycles, including core scaffolds of biologically active natural products.[1,2,3]
We have reported that oxo-1,6-enynes react in the presence of gold(I) complexes to give oxatricyclic compounds through a formal [2+2+2] alkyne/alkene/carbonyl cycloaddition process.[4]
The transformation presumably proceeds by attack of the carbonyl on the cyclopropyl gold carbene intermediate followed by Prins cyclization and deauration to afford the final oxatricyclic derivative.[4]
Summary
The product was purified by silica gel column chromatography eluting with cyclohexane/EtOAc (9:1) to afford a colorless oil (184 mg, 86%); 57% yield over 2 steps (69% based on recovered starting material). The product was purified by silica gel column chromatography eluting with cyclohexane/EtOAc (95:5 to 4:1) and isolated as a colorless oil (109 mg, 29% over 2 steps; 75% based on recovered starting material) (plus 184 mg of recovered aldehyde, 61%).
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