Synthesis and Crystal Structure of (2S,4ar,8ar)-6-oxo-2,4a,6,8a-tetrahydropyrano[3,2-b]pyran-2-carboxamide

(2S,4aR,8aR)-6-Oxo-2,4a,6,8a-tetrahydropyrano[3,2-b]pyran-2-carboxamide, a potentially effective antibacterial agent, was prepared by a chemoselective hydration of the corresponding nitrile using a heterogeneous catalytic method based on copper(II) supported on molecular sieves, in the presence of acetaldoxime. It belongs to a new class of pyranopyrans that possess antibacterial and phytotoxic activity.