Tetronic acid amide

Basler, B., Schuster, O., and Bach, T. (2005) Conformationally constrained p-amino acid derivatives by intramolecular [2 + 2]-photocycloaddition of a tetronic acid amide and subsequent lactone ring opening. Journal of Organic Chemistry, 70, 9798-9808. 

Acid derivatives including esters, amides, halides and nitriles are readily accessible. Dicyanofuroxan (72) shows in its reactions some similarities to phthalonitrile (75LA1029) it also provides a source of fused pyridazino- and oxazino-furoxans (73) and (74) via addition with hydrazine and hydroxylamine, respectively (82H(19)1063). The tetronic acid compound (75) yields a hydroxyamide (76) on aminolysis (79S977). 

FIG. 1 5-Membered rings composed of P-ketocaiboxylic esters ( tetronic acids, 1), P-ketocarboxylic thioesters ( thiotetronic acids, 2) or P-ketocarboxylic amides ( tetramic acids, 3), and their respective tautomers. 

Aldonamides are readily prepared by reaction of lactones with liquid ammonia (86,99,100), with ammonium hydroxide (101,102), or by bubbling ammonia gas into alcoholic solutions of the sugar lactones (103-104). Aldonamides of the tetronic adds are stable in aqueous solution (105), but penton- or hexon-amides are hydrolyzed, as shown by the change of the optical rotation of the amide solutions (106). The hydrolysis is catalyzed by acids and bases, and the product was the ammonium salt of the aldonic acid. 

The title phosphonate and related substances undergo thermal decomposition to B-acyl ketenes at temperatures in excess of 50°C. Thus thermolysis in the presence of alcohols, amines, a-hydroxy esters, and a-amino esters affords the corresponding g-keto esters and amides the latter two classes can be cyclized upon subsequent base treatment to unsaturated tetronic and tetramic acids and the related phosphonate reagents. ... 

TETRON or TETRON-100 (107-49-3) Reacts with water, forming phosphoric acid and flammable ethylene gas. Alkalis or elevated temperatures above 300°F/150°C can cause decomposition, forming flammable ethylene gas and phosphorus oxides. Aqueous solution is incompatible with sulfuric acid, alkalis, ammonia, aliphatic amines, alkanolamines, alkylene oxides, amides, epichlorohydrin, nitromethane, organic anhydrides, isocyanates, vinyl acetate. Attacks some plastics, mbber, and coatings. Corrosive to metals in the presence of moisture. 

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