98171-30-3Relevant academic research and scientific papers
Cycloadditions of 6H-1,3,4-Oxadiazin-6-ones (4,5-Diaza-α-pyrones). 14. Reactions of 6H-1,3,4-Oxadiazin-6-ones with Norbornene: Non-catalysed and Catalysed by Trifluoroacetic Acid
Christl, Manfred,Bodenschatz, Gabriele,Feineis, Erich,Hegmann, Joachim,Huettner, Gerhard,et al.
, p. 659 - 674 (2007/10/03)
In 11 out of 13-non-catalysed reactions of oxadiazinones 1 with norbornene, γ-oxoketenes 4 were observed and could be isolated in three cases (4b,d,m).Except for 4m, all γ-oxoketenes isomerised to enollactones of type 5 on thermolysis.However, 4b furnished the cyclobutene derivative 10 as the major product.No γ-oxoketenes were detected in the reactions of 1k and 1l which gave rise to the formation of 5k and the enollactone 19, respectively.The latter was converted into 5l on treatment with trifluoroacetic acid (TFA).Four oxadiazinones 1 were allowed to react with norbornene in the presence of TFA.Three of them (1a,b,l) afforded mixtures of enollactones of type 5 and their diastereomers 12.Heating of 4 in the presence of norbornene led to the formation of the symmetrical δ-lactones 6.This process was observed to be efficient only where the conversion 4 -> 5 is slow (4b) or inoperative (4m).In five cases, the treatment of the components with boron trifluoride etherate proved to be a useful preparative alternative (6a,d,g,h,m).On treatment of 4a with methanol, the pseudoester 7a was formed, whereas 4b gave mixtures of 7b and the esters 8b and 15.Hydrogen chloride converted 4b into the pseudochloride 14, which furnished pseudoester 7b on methanolysis.Reaction of 4b,m with formic acid gave rise to pseudoahydrides of type 13.From 4b and TFA a mixture of the enollactones 5b and 12b was obtained.Boron trifluoride etherate transformed 4i to enollactone 12i; analogously, 12m resulted on treatment of 4m with trifluoromethanesulfonic acid.
Cycloadditions of 6H-1,3,4-Oxadiazin-6-ones (4,5-Diaza-α-pyrones), 11. - δ-Chloro δ-Lactones from γ-Oxo Ketenes
Hegmann, Joachim,Ditterich, Elke,Huettner, Gerhard,Christl, Manfred,Peters, Eva-Maria,et al.
, p. 1913 - 1918 (2007/10/02)
Prepared from 1,3,4-oxadiazinone 1 with norbornene, cyclopentene, cyclopentadiene, and indene, the γ-oxo ketenes 2, 5, 6, and 7 have been converted into the δ-chloro δ-lactones 3, 8, 9, and 10, respectively, by treatment with hydrogen chloride.The configu
CYCLOADDITIONS OF 1,3,4-OXADIAZIN-6-ONES
Christl, Manfred
, p. 1 - 18 (2007/10/02)
From substituted 2-oxoethanoic acids and acylhydrazines the corresponding hydrazones 1 are prepared, which can be cyclized to give the title compounds 2.The reactions of 2 with activated alkynes (yneamines, cyclooctyne, dehydrobenzene) proceed as -cycloadditions and result in the formation of α-pyrones after loss of nitrogen.Reactions of this type are possible also intramolecularly, if the oxadiazinones (2r-u) contain a properly located alkyne group.Oxadiazinones 2 undergo Diels-Alder cycloadditions with a variety of olefins.Diaryloxadiazinones react with alkenes which are activated by ring strain (cyclopropene, cyclobutene, trans-cyclooctene), by a high-lying HOMO (benzvalene, styrene, enamines), or by the factor > in the case of norbornene.The methyl phenyloxadiazinonecarboxylate 2p is highly reactive and takes up even 1-octene and cyclohexene.The primary adducts of type 54 readily extrude nitrogen to give 4,5-dihydropyrylium-2-olates (60) as most probable but not observed intermediates.In one case the expected -cycloadduct, namely 26, could be isolated.The ultimate products are generally derived either from 60 or from γ-keto ketenes 53, which are believed to be in equilibrium with 60. γ-Keto ketenes 53 have been detected with many systems and are stable in certain cases.When diphenyloxadiazinone, 2a, was treated with norbornene, norbornadiene, cyclopentene, trans-cyclooctene, or styrene, enol lactones of type 63 were isolated, which are considered to be formed from the intermediate dihydropyryliumolates 62 by a suprafacial -H shift.Cyclopropenes and cyclobutene transform oxadiazinones 2 to α,β-unsaturated seven-membered enol lactones 64-67 and eight-membered enol lactone 69, respectively.These products are believed to be the result of valence isomerizations of the corresponding dihydropyryliumolates (74, 75).Enamines behave exceptionally in that they can convert the oxadiazinones 2 into products not derived from the -cycloaddition (e.g. 82, 88, 89), although the latter process is dominating in most examples investigated to date.The compounds obtained from the usual -cycloadditions are amides of α,β-unsaturated δ-oxo acids (78, 80) and α,β-unsaturated δ-amino-δ-lactones (81).The former are believed to arise from α-amino-γ-keto ketene intermediates (76) by -amino migrations, whereas the formation of the latter (81) can be rationalized in two different ways, one being a -amino migration starting from the possible intermediates 85 (4-amino-4,5-dihydropyrylium-2-oltes).Cyclobutanone derivatives 50 and 52 and cyclopentanone derivatives 16 originate from γ-keto ketenes generated from cis,trans-1,5-cyclooctadiene, o-vinylstyrene, and benzvalene, respectively.In these cases, intramolecular cycloaddition of the ketene functionality occurs across either the CC double bond or the strained bicyclo-butane sigma bond, respectively.Intermolecular -cycloadditions of the corresponding γ-keto ketenes with cyclopentadiene, 2,3-dihydrofuran, and ...
