A New Expedient Synthesis of 3-Methyl-2(5H)-furanone, the Common Substructure in Strigolactones, and Its Proposed Biosynthesis

Abstract

3-Methyl-2(5H)-furanone is the common structural unit in natural and several synthetic strigolactones, which are germination stimulants for seeds of the parasitic weeds Striga and Orobanche spp. A simple, one-step, ring-closing metathesis of allyl methacrylate using an appropriate Grubbs catalyst gives this fur­anone in good yield. Acid-catalyzed condensation of glyoxal and methylmalonic acid gives 5-hydroxy-3-methyl-2(5H)-furanone, which is another synthon for the introduction of the furanone unit into strigolactones. In addition, a biosynthetic pathway is presented for the incorporation of the furanone unit into strigolactones, which is relevant in view of the current interest in the newly discovered ­biological functions of strigolactones.