Rearrangement and polar reaction of carbethoxymethylene in 2-propanol

Strausz, O. P.; Thap, Do Minh; Gunning, H. E.

doi:10.1021/ja01008a052

Cited by 26 publications

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“…[106,120] However, the use of protic solvents such as methanol had lead to the formation of Wolff rearrangement and O-H insertion products and consequently a considerable decrease in the formation of -lactam. At this point, an analogy was made with the prior results on the photolysis of ethyl diazoacetate in methanol [74] and in iso-propanol [76] in which intermolecular C-H insertion products were suppressed. Due to these observations, it was assumed that the formation of the two lactams should arise from different pathways, in which the -lactam transition state originates a greater charge separation.…”

Section: Scheme 41mentioning

confidence: 95%

“…Despite the good yields obtained for these two examples, the presence of substituents with less migratory aptitude usually leads towards the formation of product mixtures resulting from other kind of reactions like O-H and C-H insertion with the solvent. [74][75][76][77] As a way to apply the -diazo carbonyl photolysis as a synthetic tool, a work by Liao and co-workers compared the Rh 2 (OAc) 4 catalyzed decomposition of compounds possessing a free hydroxyl functional group with photolytic decomposition. While in the former the expected O-H insertion products were obtained in good yields, the photolysis led to the formation of Wolff rearrangement products, tetrahydrofurans derivatives, in reasonable yields (33-78 %).…”

Section: Scheme 19mentioning

confidence: 99%

“…Alcohols were thought to react selectively with singlet carbenes to generate ethers (Scheme 26). [76,94] Despite the utility of this reaction, [95] the mechanism is not yet fully clarified but recent developments have been made on this area.…”

Section: O-h Insertionmentioning

confidence: 99%

“…[40] 2-Diazoethyl acetate 70 was reported to react with iso-propanol via a polar addition of the carbene, in the light of what was known in 1960's (Scheme 30, pathway a). [75,76] Recently, an ylide deriving from the singlet carbene 1 71 was assigned to be the intermediary based on kinetic data obtained in Freon 113 photolysis (Scheme 30, pathway b). [61] Furthermore, the methylester analogue was seen to react with iso-propanol to yield the corresponding ethers at room temperature while in a rigid matrix the C-H insertion products predominate due to the reaction of the triplet carbene (abstraction-recombination mechanism, vide infra) that becomes predominant at lower temperatures.…”

Section: Scheme 29mentioning

confidence: 99%

“…[42] The C-H insertion reaction of analogues of 86 on a series of alcohols (MeOH, EtOH, i-PrOH and t-BuOH) was also reported despite the low yields due to the formation of rearrangement and O-H insertion products (see above). [75,76] Analogously, -diazoamides 82-84…”

Section: C-h Insertionmentioning

confidence: 99%

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Developments in the Photochemistry of Diazo Compounds

Candeias¹,

Afonso

2009

COC

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This review focus on photolytic reactions of diazo compounds, covering mainly synthetic applications such as Wolff rearrangement, 1,2-shift, X-H insertion, cyclopropanation, hydrogen abstraction and reaction with oxygen and physical organic studies, with special relevance to mechanistic considerations. the synthesis of a diazo compound if loss of a proton from the C()-atom of the primarily formed alkanediazonium ion is faster than the loss of dinitrogen, which makes this method almost specific for the case of aliphatic amines containing a C()-atom substituted by an acidifying group. Diazo compounds can also be prepared by acylation or cleavage of aliphatic diazo compounds containing the structural requirements. For instance, diazo carbonyl carbamate 4 can be prepared through the reaction of the carboxylate precursor with a chloroformate and further reaction of the anhydride with diazomethane (Scheme 2).[13] Making use of oxidants, diazo carbonyl compounds can be prepared by hydrazone oxidation in the presence of mercury oxide and potassium hydroxide.[14] Scheme 1 Scheme 2 Diazo-transfer reactions have been widely used since they are a more general method for the preparation of diazo compounds. In this reaction, the diazo moiety is transferred from the donor to an acceptor where the donor is a sulphonyl azide (6) and the acceptor a carbanion formed after deprotonation (Scheme 3).[3,15] Scheme 3 Diazo compounds can be submitted to several reaction conditions and myriads of compounds can be obtained by the proper choice of conditions and reagents. In the absence of a metal catalyst, this decomposition can be induced by thermolysis or photolysis, generating a highly reactive intermediate species that, in most cases, affords a complex mixture of products. Depending on the diazo compound and the reaction conditions, the resulting products can be derived from C-H or X-H

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Section: Scheme 41mentioning

confidence: 95%

Section: Scheme 19mentioning

confidence: 99%

Section: O-h Insertionmentioning

confidence: 99%

Section: Scheme 29mentioning

confidence: 99%

Section: C-h Insertionmentioning

confidence: 99%

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Developments in the Photochemistry of Diazo Compounds

Candeias¹,

Afonso

2009

COC

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Die Wolff‐Umlagerung von α‐Diazocarbonyl‐Verbindungen

1975

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Die synthetisch leicht zuganglichen a-Diazocarbonyl-Verbindungen zeichnen sich durch eine hohe Reaktivitat aus, die unter modifizierten Bedingungen eine Vielzahl von praparativen Moglichkeiten eroffiiet. Bei der thermisch, photochemisch oder katalytisch induzierten Wolff-Umlagerung gehen die a-Diazocarbonyl-Verbindungen in Ketene uber. Als Zwischenstufen oder Ubergangszustande werden freie und komplexierte Carbene, 1,3-Dipole, 1,3-Diradikale und die antiaromatischen Oxirene diskutiert. Der vorliegende Fortschrittsbericht versucht, praparative und theoretische Aspekte zu integrieren.Die Schliisselpositionen in den Resten konnen auch Heteroatome einnehmen. Besonders wichtig sind dabei die cc-Diazocarbonsaure-Derivate ( l ) , R ' = O R , NH2, NHR, NR2 etc.Ein einfaches analytisches Charakteristikum fur die offenkettige cc-Diazocarbonyl-Struktur ist neben der CO-Valenzschwingung die zwischen 2090 und 2190cm-' (meistens bei 2130 cm-') liegende Diazobande im IR-Spektrum. Die gegenseitige Beeinflussung von Diazo-und Carbonylgruppe erniedrigt die CO-Frequenz und erhoht die N2-Frequenz. a-Diazocarbonyl-Verbindungen sind besonders reaktive Substanzen. Die Umsetzungen unter Verlust der N2-Gruppe werden im allgemeinen thermisch, photochemisch, katalytisch oder mit (Lewis-)Sauren eingeleitet. Wahrend die Zersetzung mit Sauren sich auf alle Diazoalkane ubertragen la&, beobachtet man bei den drei anderen Prozessen eine fur a-Diazocarbo-52 Angew. Chem. 187. Jahrg. 1975 J N r . 2 Katalyse

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The Wolff Rearrangement of α‐Diazo Carbonyl Compounds

Meier¹,

Zeller

1975

Angew. Chem. Int. Ed. Engl.

260

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further literature cited therein.[225] If oxygen is passed into solutions of lithionitrosamines at low temperature. or if peroxides [di-tert-butyl peroxide, bis(trimethylsilyl) peroxide] are added, then vigorous evolution of gas rapidly sets in on warming or on attempted evaporation. The structure of the decomposition products, which we are currently examining, should reveal whether the a-hydroxy nitrosamine derivatives postulated in Scheme 6 are actually formed.[226] M.The readily accessible u-diazo carbonyl compounds are distinguished by their high reactivity, which opens up a variety of preparative applications under modified conditions. Wolff rearrangements of these compounds, induced thermally, photochemically, or catalytically, afford ketenes. Free and complexed carbenes, 1,3-dipoles, 1,3-diradicals, and the antiaromatic oxirenes have been considered as intermediates or transition states. The present progress report attempts to integrate preparative and theoretical aspects.

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Rearrangement and polar reaction of carbethoxymethylene in 2-propanol

Cited by 26 publications

References 0 publications

Developments in the Photochemistry of Diazo Compounds

Developments in the Photochemistry of Diazo Compounds

Die Wolff‐Umlagerung von α‐Diazocarbonyl‐Verbindungen

The Wolff Rearrangement of α‐Diazo Carbonyl Compounds

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