De-novo approach for a unique spiro skeleton-1,7-dioxa-2,6-dioxospiro[4.4]nonanes

2-Oxoglutaric acid () underwent facile indium mediated allylation with allyl bromide (), and ethyl 4-bromocrotonate (), cinnamyl bromide () and subsequent in situ dehydration to provide respective 5-oxotetrahydrofuran-2-carboxylic acids (90–95%). The reaction of with and proceeded with high regio and stereo selectivity to provide only γ-addition products with syn stereochemistry as ascertained from their cyclic products. Compounds underwent diastereoselective iodocyclization to provide respective 1,7-dioxa-2,6-dioxospiro[4.4]nonanes . The relative stereochemistries have been ascertained by single crystal X-ray structures, NOE experiments and coupling constants in 1H NMR spectra.