ISSN:
0009-2940
Keywords:
1,3,4-Oxadiazine-2-carboxylate, methyl 6-oxo-5-phenyl-
;
Diels-Alder reactions
;
Ketenes, γ1-oxo-
;
1,2-Cyclopentanedione derivatives
;
Adipic acid, substituted 2-oxo-dimethyl esters
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Cycloadditions of 6H-1,3,4-Oxadiazin-6-ones (4,5-Diaza-α1-pyrones), 12[1]. - Dieckmann Condensations without BasesPrepared by treatment of methyl 6-oxo-5-phenyl-6H-1,3,4-oxadiazine-2-carboxylate (1) with norbornene, norbornadiene, and styrene, respectively, the γ1-oxoketenes 2, 5, and 7 were allowed to react with methanol. Inter alia, the semiacetals 3, 6, and 10 of 1,2-cyclopentanedione derivatives were formed. The identity of 3 has been established by an X-ray structure analysis. The pathway to these compounds seems to be closely related to the mechanism of the Dieckmann condensation. By using [D4]methanol, it has been shown that the semiacetal methoxy group underwent an intramolecular [1,2] migration. Methanol was eliminated from semiacetal 10 by chromatography on silica gel with formation of the enol 11. In addition to 3 and 10, the dimethyl adipates 4 and 9 were observed as the expected methanolysis products of the γ1-oxoketenes 2 and 7, respectively. The diesters 9 were obtained on a second route from 7. Treatment of 7 with trifluoroacetic acid and subsequent hydrolysis gave rise to the monoesters 12, which were converted into the diesters 9 by conventional esterification.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931260334
Permalink
