On the Reaction of Carbonyl Compounds with 3,5-Dihydroxy-4-phenylisoxazole. A Novel Type of Noncatalyzed Condensation and Carbon-Carbon Bond Formation

3,5-Dihydroxy-4-phenylisoxazole reacts spontaneously with a variety of carbonyl compounds yielding with aromatic aldehydes A^T-arylmethylidene-4-phenylisoxazol-5-onium-3-enolates and with acetone a 1:2 condensation product. The latter undergoes reaction with alcohols giving 5-alkoxy-2-oxo-3-phenyl-5,7,7-trimethyl-2H,7H-isoxazolo[3,2-6] [l,3]oxazine. Crotonaldehyde, acrolein, and mesityl oxide reacted with the initial isoxazole. Structures and properties of the various products are studied.