Oxidative cleavage of indane-1,2,3-trione-ene adducts; a convenient synthesis of allyl and allenyl carboxylic acids

Abstract

The ene adducts formed by the thermal reaction of indane-1,2,3-trione with olefins or terminal alkynes are cleaved in good yield by reaction with periodic acid in dry diethyl ether. Thereby the 2-hydroxyindane-1,2-dione moiety in the adduct is replaced by a CO₂H group; hence indane-1,2,3-trione is a masked equivalent of carbon dioxide in the ene reaction. The allyl or allenyl carboxylic acid may be separated from the co-products (phthalic acid and anhydride) by extraction into hexane.