α,β‐Epoxyketon → Alkinon‐Fragmentierung II: Pyrolytischer Zerfall der Hydrazone aus α,β‐Epoxyketonen und N‐Amino‐aziridinen. Über synthetische Methoden, 4. Mitteilung

Felix, Dorothée; Müller, Renate; Horn, Ulrich; Joos, R.; Schreiber, J.; Eschenmoser, Albert

doi:10.1002/hlca.19720550424

Cited by 145 publications

(60 citation statements)

References 57 publications

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“…Spectroscopic data were consistent with that previously reported. [40] 2-(2,2-Diphenylaziridin-1-yl)isoindoline-1,3-dione: Yield: 75 % from 1,1-diphenylethene, N-aminophthalimide (3) and (diacetoxyiodo)benzene (19). Spectroscopic were data consistent with that previously reported.…”

Section: Methodsmentioning

confidence: 99%

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Hypervalent Iodine‐Mediated Aziridination of Alkenes: Mechanistic Insights and Requirements for Catalysis

Desaize¹,

Wirth²

2007

Chemistry A European J

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By detailed study of the possible side reactions in the previously reported aziridination of alkenes with N-aminoheterocycles mediated by hypervalent iodine reagents, the requirements to make this reaction catalytic in iodoarene have been determined. The reaction requires an oxidant that will oxidise iodoarenes but that does not oxidise alkenes, but it is possible that no such oxidant actually exists! A method in which the hypervalent iodine reagent can be recycled without the need for reisolation is possible. Further study into the mechanism of this reaction gives tentative evidence that the reaction proceeds through formation of an aminoiodane that reacts directly with the alkene, contrary to previous literature reports in which an acetoxyamine intermediate is suggested. The temperature effect of this reaction is remarkable.

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Section: Methodsmentioning

confidence: 99%

“…Spectroscopic data consistent with that previously reported. [40] Enantiomeric excess determinations were carried out by using a Chirapak AD column eluting with hexane/2-propanol 90:10 at a flow rate of 0.5 mL min À1 at room temperature. Yield: 79 % from cis-stilbene, N-aminophthalimide (3) and (diacetoxyiodo)benzene (19).…”

Section: Methodsmentioning

confidence: 99%

Hypervalent Iodine‐Mediated Aziridination of Alkenes: Mechanistic Insights and Requirements for Catalysis

Desaize¹,

Wirth²

2007

Chemistry A European J

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“…The yields of epoxides are high and rearrangement to the aldehydes, some of which are very sensitive materials, is also a high yield process. This route is efficient to either pure a-cyclocitral(29) [8] or P-cyclocitral (32)2).…”

mentioning

confidence: 99%

The Synthesis of β,γ‐ and α,β‐Unsaturated Aldehydes via Polyene Epoxides

Rosenberger

Jackson

Saucy

1980

Helvetica Chimica Acta

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SummaryA substitute for the Darzens glycidic ester synthesis for converting unsaturated ketones or aldehydes into the homologated b, y -or a,B-unsaturated aldehydes employing sulfur ylides is described. The carbonyl group is converted into the unsaturated oxirane which is then rearranged to the new aldehyde. High yields of isomerically pure aldehydes are available by this method and the process is of practical importance in the conversion of p-ionone into the p-CI4-aldehyde, a key intermediate in the Isler synthesis of vitamin A. The efficient preparation of aand /I-cyclocitral by the novel process is also described.The development of a commercial synthesis of vitamin A by Isler et al. is one of the major industrial achievements of the fifties [l]. This complex process [ 2 ] is still the major source of this essential vitamin, and the overall synthetic scheme has changed very little in the past twenty-five years.One key step of this process is the formal addition of one C-atom to p-ionone (1) (Scheme I ) , using the Darzens glycidic ester [3] reaction and proceeding through the aldehyde 2 originally used by Milas et al.[4] in their vitamin-A work; the glycidic ester is hydrolyzed, decarboxylation then leads to the aldehyde enolate and kinetic protonation results in the aldehyde 2; further exposure to base then yields the thermodynamic product 3. While the overall yield for this transformation is good (84-86%), the economy of the process in today's market place leaves much to be desired. An excess of methyl chloroacetate and sodium methoxide has to be used to add the C-atom and it would be better to just add this C-atom without waste.A similar process involving epoxide 4, can also be envisioned as a possible route to 2. Therefore, the epoxide 4 was prepared (94% yield) from p-ionone (1) by the action of (dimethylsu1fonio)methanide [ 5 ] . The conversion of this epoxide to the aldehyde 2 initially proved difficult but eventually yielded to the action of magnesium bromide [6].

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“…An analogous reaction sequence was observed on photolysis of 38+ IX +39 [14] Scheme 9 lo) This transformation involving a dienone as leaving group represents a novel type of the Eschenrnuser fragmentation [15].…”

mentioning

confidence: 68%

Photochemical Reactions. 129th Communication. Photochemistry of a conjugated diepoxydiene: Product formation via carbonyl ylide and carbene intermediates with participation of neighbouring epoxy functions

Bischofberger

Frei

Jeger

1983

Helvetica Chimica Acta

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In memoriam Hans Heusser (8.VI. 83) SummaryOn singlet excitation (A = 254 nm, acetonitrile) the diepoxydiene (E)-7 undergoes photocleavage to the carbonyl ylide VII and the carbenes X and XI. The carbonyl ylide VII rearranges to the thermally labile dioxabicyclo [3.2.1 Ioctene 20 or fragments via VIII to the aldehyde 9 and propyne. The carbene X, showing behaviour typical of vinyl carbenes, undergoes addition to the adjacent double bond furnishing the cyclopropene 11. The carbene XI, however, undergoes an insertion reaction into the neighbouring oxirane C, C-bond leading to the oxetene (E)-21 which can be isolated at -78", but at room temperature is rapidly transformed to the aldehyde 10.On triplet excitation (acetone, A > 280 nm), however, (E)-7 shows the typical behaviour of epoxydienes, undergoing C, 0-cleavage of the oxirane and isomerization to 22,23 and (E/Z)-24.

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α,β‐Epoxyketon → Alkinon‐Fragmentierung II: Pyrolytischer Zerfall der Hydrazone aus α,β‐Epoxyketonen und N‐Amino‐aziridinen. Über synthetische Methoden, 4. Mitteilung

Cited by 145 publications

References 57 publications

Hypervalent Iodine‐Mediated Aziridination of Alkenes: Mechanistic Insights and Requirements for Catalysis

Hypervalent Iodine‐Mediated Aziridination of Alkenes: Mechanistic Insights and Requirements for Catalysis

The Synthesis of β,γ‐ and α,β‐Unsaturated Aldehydes via Polyene Epoxides

Photochemical Reactions. 129th Communication. Photochemistry of a conjugated diepoxydiene: Product formation via carbonyl ylide and carbene intermediates with participation of neighbouring epoxy functions

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