78371-30-9

Upstream product

• 121-46-0 bicyclo[2.2.1]hepta-2,5-diene 
• 63617-45-8 2,5-diphenyl-6H-1,3,4-oxadiazin-6-one 
• 121-46-0 bicyclo[2.2.1]hepta-2,5-diene 

Downstream Products

• 78371-31-0 ((1S,2S,3S,4R)-3-Benzoyl-bicyclo[2.2.1]hept-5-en-2-yl)-phenyl-acetic acid methyl ester 

Relevant academic research and scientific papers

Cycloadditions of 6H-1,3,4-oxadiazin-6-ones (4,5-diaza-α-pyrones), 15. Reactions of 6H-1,3,4-oxadiazin-6-ones with norbornadiene. A new route to 3,6-disubstituted α-pyrones

Upon reaction with norbornadiene, ten disubstituted 1,3,4-oxadiazin-6-ones 1 were converted into 3,6-disubstituted α-pyrones 6. For this purpose, solutions of the substrates were treated with boron trifluoride-ether or trifluoroacetic acid. The smooth formation of 6 was also observed when a γ-oxo ketene, initially generated by heating a solution of the substrates in the absence of boron trifluoride-ether, was allowed to react with the Lewis acid. Without use of an acid, only 6f could be obtained free from further compounds, whereas in the other cases enol lactones and 1:2 products of the types 8 and 7 were formed additionally. Oxadiazinone 1j gave enol lactone 10 in the noncatalysed reaction. VCH Verlagsgesellschaft mbH, 1996.

CYCLOADDITIONS OF 1,3,4-OXADIAZIN-6-ONES

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 ...

Cycloadditions of 6-Oxo-1,3,4-oxadiazines (4,5-Diaza-α-pyrones), 3. Reactions of 6-Oxo-2,5-diaryl-1,3,4-oxadiazines with Alkenes

Cycloaddition of the known 6-oxo-2,5-diphenyl-6H-1,3,4-oxadiazine (1a) and the new 2,5-diaryl derivatives 1b - g with various alkenes yield nitrogen free products.Using cyclopropenes and cyclobutene, α,β-unsaturated seven-membered enollactones 42 - 45 and the α,β-unsaturated eight-membered enollactone 47 are formed, respectively.In the presence of basic aluminum oxide 42a and d undergo a hydrogen migration to form the β,γ-unsaturated enollactones 46a and d, respectively.With other alkenes, γ-ketoketenes 33 have been observed, or are assumed to be intermediates, based on the structure of the isolated products.The six-membered eno llactones 10, 13, 15, 19, and 21 and 22 have been obtained with norbornene, norbornadiene, cyclopentene, trans-cyclooctene, and styrene.Compound 10 isomerizes to 34 on treatment with potassium tert-butoxide.The methanolyses of these enollactones result in the formation of the diastereomeric methyl esters 12 and 35.The γ-ketoketene 16 formed from trans-cyclooctene gives acid 17 and ester 18 with water and methanol, respectively.These reactions are faster than the cyclization to enollactone 19.From cis,trans-1,5-cyclooctadiene the more short-lived γ-ketoketene 40 is formed, which undergoes intramolecular cycloaddition, giving rise to the tricyclic cyclobutanone derivative 41.Tetracyclic products of type 4 are generated from benzvalene (2) and 1.The structures and configurations of compounds 10, 19, and 41 have been determined by means of X-ray analyses.