Abstract: The 1, 4-addition reactions of the anions derived from various cyclic allylic sulfoxides and 2-cyclopentenones were examined. Methyl substitution at C-3 of 2- cyclopentenones hinders the 1, 4-addition. The activated enone, 2-(methoxy-carbonyl)-3- methyl-2-cyclopentenone (4), however, afforded excellent chemical and optical yields of the 1, 4-adducts.
![9-bromo-8-methyl-1,4-dioxaspiro[4.4]non-8-ene Structure](https://image.chemsrc.com/caspic/132/70156-97-7.png)