PREPARATION AND NITROSATION OF 3,4-DIMETHYL-3-PENTEN-2-ONE (E)-OXIMES AND (Z)-OXIMES - FORMATION OF 3,3,4,5-TETRAMETHYL-3H-PYRAZOLE 1,2-DIOXIDE AND OF 2-ISOXAZOLINE DERIVATIVES

The stereoisomeric (E)- and (Z)-oximes of 3,4-dimethyl-3-penten-2-one were prepared and nitrosated with butyl nitrite in methanol. The (E)-oxime gave 3,3,4,5-tetramethyl-3H-pyrazole 1,2-dioxide in nearly quantitative yield, while the (Z)-oxime reacted less readily, giving a lower yield of the same product, with five other products identified as isoxazoline derivatives. Three of these were 4-hydroxy-, 4-methoxy-, and 4-nitro-3,4,5,5-tetramethyl-2-isoxazoline. The fourth was the O-(3,4,5,5-tetramethyl-2-isoxazolin-4-yl) derivative of the starting (Z)-oxime, and the fifth was 4-methylene-3,5,5-trimethyl-2-isoxazoline.