Cycloadditionen von 6H‐1,3,4‐Oxadiazin‐6‐onen (4,5‐Diaza‐α‐pyronen), 15.Reaktionen von 6H‐1,3,4‐Oxadiazin‐6‐onen mit Norbornadien. Ein neuer Weg zu 3,6‐disubstituierten α‐Pyronen

Abstract

Cycloadditionen von 6H-1,3,4-0xadiazin-6-onen (4,5-Diaza-a-pyronen), 1 5L01 Reaktionen von 6H-1,3,4-0xadiazin-6-onen mit Norbornadien. Ein neuer Weg zu 3,6-disubstituierten a-Pyronen* Upon reaction with norbornadiene, ten disubstituted 1,3,4-strates in the absence of boron trifluoride-ether, was aloxadiazin-6-ones l were converted into 3,6-disubstituted a-lowed to react with the Lewis acid. Without use of an acid, pyrones 6. For this purpose, solutions of the substrates were only 6f could be obtained free from further compounds, treated with boron trifluoride-ether or trifluoroacetic acid. whereas in the other cases enol lactones and 1 : 2 products of The smooth formation of 6 was also observed when a y-0x0 the types 8 and 7 were formed additionally. Oxadiazinone ketene, initially generated by heating a solution of the sub-1 j gave enol lactone 10 in the noncatalysed reaction.