A metal-free one-pot cascade method involving NaBH4 and microwave (MW)-heating efficiently synthesized lactones, including the industrially significant γ-valerolactone at 90% yield. The process directly converts methyl levulinate, succinic acid and a wide range of aliphatic and aromatic ketoacids, in H2O or THF, proceeding via reduction, COOH proton exchange, cyclization, and dehydration, showing promise for biomass conversion.