General Synthesis of 1-Oxaspiro[4.5]decan-2-ones and 1-Oxaspiro[4.5]decanes from 5-Methylene-2(5H)-furanone

5-Methylene-2(5H)-furanone underwent Diels-Alder cycloadditions to butadiene and several acyclic and cyclic C-substituted dienes, respectively, affording bicyclic and tricyclic spiroadducts in good yields. These compounds are precursors of other unsaturated and saturated spirolactones and also spiroethers, which were obtained through simple chemical reactions, i.e., hydrogenation of C-C double bonds, reduction of the carbonyl group, and Michael addition. The synthesis of 32 spirolactones and eight spiroethers illustrates the scope and efficiency of this method. Many of these products are suitable for use as components of perfumes and aromas owing to their olfactive properties. © 1991, American Chemical Society. All rights reserved.