Replacement of the tertiary bases by calcium oxide or potassium hydroxide (in benzene) gave unsatisfactory results; in the latter case 11% of impure protoanemonin was obtained. The dichlorovalerolactone, unlike the dibromide, is difficult to prepare, as addition of chlorine to the a-apgelica lactone (11) always is accompanied by substitution. The dichlorolactone yielded with tertiary amines only an unsaturated monochlorolactone, probably analogous ...
![3-[(5-nitro-2-furyl)methylideneamino]-1,3-oxazinan-2-one Structure](https://image.chemsrc.com/caspic/445/4341-15-5.png)