Synthesis of 2,8-dioxabicyclo[3.3.1]nonane derivatives via a sequential Knoevenagel condensation and hetero-Diels-Alder reaction in an aqueous medium.

Utilizing aldehyde-substituted vinylogous carbonates and 1,3-diketones, a simple protocol is presented for the synthesis of 2,8-dioxabicyclo[3.3.1]nonane derivatives via Knoevenagel condensation followed by a hetero-Diels-Alder reaction under green reaction conditions. The structure of a key product is unequivocally confirmed by X-ray crystallography.