664973-48-2Relevant academic research and scientific papers
Cycloadditions of 1,3,4-Oxadiazin-6-ones (4,5-Diaza-α-pyrones), 9. - Methyl 6-Oxo-5-phenyl-1,3,4-oxadiazin-2-carboxylate - Synthesis and Reactions with Norbornene, Norbornadiene, Cyclopropenes, Cyclobutene, and Benzvalene
Christl, Manfred,Lanzendoerfer, Ulrike,Groetsch, Maria M.,Ditterich, Elke,Hegmann, Joachim
, p. 2031 - 2037 (2007/10/02)
Methyl 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 deg 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 tetracyclo2,8.04,6>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.
