A general procedure for the synthesis of functionalized spiroketals from lactones is described. Addition of the lithium acetylide of cis-1-methoxy-1-buten-3-yne to lactones followed by a hydration of the acetylene, hydrolysis of the enol ether and cyclization gives excellent yields of spiroketals containing a useful enone functionality.
![1,7-dioxaspiro[5.5]undec-2-en-4-one结构式](https://image.chemsrc.com/caspic/466/88400-05-9.png)
![1,6-dioxaspiro[4.5]dec-7-en-9-one结构式](https://image.chemsrc.com/caspic/449/88400-10-6.png)
