The Synthesis of Cyclohexane-1,3-diones Bearing an Isoxazoline or a Dihydro-1,2-oxazine Ring at C2

Dimedone (6) was C-acylated with 4-(1′-methylethylideneaminooxy) butanoic acid (7), and the product (8) was hydrolysed to give 2-(5′,6′-dihydro-4′H-1′,2′-oxazin-3′-yl)- 5,5-dimethylcyclohexane-1,3-dione (3). The 2-(4′,5′-dihydroisoxazol-3′-yl) 1,3-dione (4) was obtained in <2% yield from dimedone anion and 3-nitro-2-isoxazoline (11).