Cycloadditionen von 6H-1,3,4-Oxadiazin-6-onen (4,5-Diazaα-pyronen), 11. δ-Chlor-δ-lactone aus γ-Oxoketenen

✍ Scribed by Hegmann, Joachim ;Ditterich, Elke ;Hüttner, Gerhard ;Christl, Manfred ;Peters, Eva-Maria ;Peters, Karl ;Von Schnering, Hans Georg

• Publisher: Wiley (John Wiley & Sons)
• Year: 1992
• Tongue: English
• Weight: 642 KB
• Volume: 125
• Category: Article
• ISSN: 0009-2940
• DOI: 10.1002/cber.19921250819

✦ Synopsis

Diels-Alder reactions 1 Ketenes, y-0x0-6-Lactones, 6-chloro-/ P-Lactones Cycloadditions of 6H-1,3.4-0xadiazin-6-ones (4.5-Diaza-a-pyrones), 11 [*I. -6-Chloro &Lactones from y-0x0 Ketenes

Prepared from 1,3,4-oxadiazinone 1 with norbornene, cyclopentene, cyclopentadiene, and indene, the y-0x0 ketenes 2, 5, 6, and 7 have been converted into the 6-chloro S-lactones 3,8, 9, and 10, respectively, by treatment with hydrogen chloride. The configuration of 10 has been determined by an X-ray structural analysis. These pseudo chlorides prove to be stable against methanol. Only in the presence of sulfuric acid as catalyst 3 suffers methanolysis to yield diester 4. On thermolysis, the y-0x0 ketenes are transformed into p-lactones. In particular, 6 and 7 gave 13 and 12, respectively. Formed also on photolysis of 6, p-lactone 13 partly isomerized to p-lactone 14 on prolonged heating.