Oxidative ring opening of 3-oxabicyclo[4.1.0]hept-4-enes, formed by the intramolecular Pt(II)-catalyzed cyclopropanation of enol ethers by alkynes, gives oxepane derivatives. Alternatively, the acid-catalyzed opening of the cyclopropane ring leads to dihydrobenzofurans or 3,4-dihydro-2H-chromenes.
![New annulations via platinum-catalyzed enyne cyclization and cyclopropane cleavage](https://www.iciq.org/wp-content/uploads/2014/03/New-annulations-via-platinum-catalyzed-enyne-cyclization-and-cyclopropane-cleavage_eng_noticies_articles_2004_2.gif)