New, regio- and diastereoselective processes are described in which readily accessible starting materials such as acrolein dimer and 2-trimethylsiloxyfuran are efficiently transformed into appropriately functionalized δ- and γ-lactones. Pertinent examples are provided by the syntheses of the mosquito oviposition attractant pheromone, cavernosine, epicarvernosine, eldanolide, L-factors, the "whisky" lactones, as well as other structurally related natural products.