ISSN:
0009-2940
Keywords:
1,3,4-Oxadiazin-6-ones
;
Diels-Alder reactions
;
γ-Oxoketenes
;
β-Lactones, bicyclic
;
Enol lactones, α,β-unsaturated
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Cycloadditions of 1,3,4-Oxadiazin-6-ones (4,5-Diaza-a-pyrones), 9. - Methyl 6-0xo-5-phenyl-1,3,4-oxadiazin-2-carboxylate - Synthesis and Reactions with Norbornene, Norbornadiene. Cyclopropenes, Cyclobutene. and BenzvaleneMethyl 6-oxo-5-phenyl-1,3,4-oxadiazin-2-carboxylate (7) was prepared by treatment of hydrazone 6 with dicyclohexylcarbodiimide. The reactions of 7 with norbornene and norbornadiene afforded the Diels-Alder adducts 8 and 9, respectively, which decomposed in solution at 20°C to give mainly the γ-oxoketenes 10 and 12 and small amounts of the β-lactones 11 and 13, respectively. The stable γ-oxoketenes 10, 12, and the bis(γ-oxoketene) 14 were obtained directly from solutions of 7 and the respective olefin. Cyclopropene, 1-methylcyclopropene, and cyclobutene were converted by 7 mainly into the oxepin derivatives 15, 17, 18 and the oxocin derivative 19, respectively. Benzvalene and 7 provided the tetracyclo[3.3.0.02,8.04,6]octanone 21. In these reactions, small quantities of β-lactones were formed, too, which together with the β-lactones 11 and 13 give evidence for the dihydropyryliumolates 24 as intermediates in the thermal denitrogenation of the Diels-Alder adducts of 7, e.g. 8 and 9.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19901231014
