Synthesis and RNase a inhibition study of c₂-symmetric bis-isochromenyl sulfones

Abstract

A new class of C₂-symmetric bis-isochromene derivatives with 3,3-linkage has been synthesized from bis-propargyl sulfones. The method involves treatment of the sulfones with triethylamine to form the isochromene derivatives presumably via the intramolecular Michael addition to the intermediate bis-allenic sulfones. Interestingly, the product expected from the Garratt-Braverman pathway was not obtained. The bis-isochromene 7d displayed RNase A inhibition activity, much stronger than the isochromene 8 and bis-isocoumarin 9.