An efficient synthesis of 5,5-spiroketals (i.e., 1,6-dioxaspiro[4.4]nonane derivatives) is described from 2-(sulfonimidoylmethylene)tetrahydrofurans involving a consecutive epoxide opening/oxa-Michael spiroketalization sequence. This methodology was applied to the very direct synthesis of chalcogran, a beetle pheromone. sulfoximine - 5,5-spiroketals - consecutive reaction - chalcogran