- A New Photochemical Synthesis of Dihydropyrazoles. Novel Mode of Photocyclization of Some 1-Iminobut-3-enes Derivatives
-
While some hydrazine derivatives 3 of 2,2-dimethyl-4,4-diphenylbut-3-enal undergo both the aza-di-?-methane (ADPM) rearrangement and a novel cyclization to afford dihydropyrazole derivatives 5 in varying yields, the tosylhydrazone derivative of 3,3-dimethyl-5,5-diphenylpent-4-en-2-one 7 gives exclusively an excellent yield of the corresponding dihydropyrazole 8, in a reaction that is proposed to involve an electron transfer process.
- Armesto, Diego,Horspool, William M.,Mancheno, Maria J.,Ortiz, Maria J.
-
-
Read Online
- The oxa-di-π-methane rearrangement of β,γ-unsaturated aldehydes
-
As far as we are aware, there are only two examples of oxa-di-π-methane (ODPM) rearrangement with β,γ-unsaturated aldehydes. However, we have discovered four other cases of this reaction, taking place with 1-methyl-3-phenyl-2-cyclohexene-1-carbaldehyde, 1
- Armesto, Diego,Ortiz, Maria J.,Ramano, Santiago
-
-
Read Online
- Influence of electron-donor sensitizers on SET-promoted photochemical reactions of β,γ-unsaturated aldehydes
-
β,γ-Unsaturated aldehydes undergo photochemical oxa-di-π-methane and decarbonylation reactions using DMN as an electron-donor sensitizer, whereas, using DMA, other photoproducts resulting from proton abstraction by ketyl- and alkene-centered radical-anion
- Armesto, Diego,Ortiz, Maria J.,Agarrabeitia, Antonia R.,Martin-Fontecha, Mar
-
p. 2261 - 2264
(2007/10/03)
-
- Photochemical reactivity of 1-substituted-1-aza-1,4-dienes promoted by electron-acceptor sensitizers. Di-π-methane rearrangements and alternative reactions via radical-cation intermediates
-
Irradiation of a series of β,γ-unsaturated imines, oxime acetates, and oxime methyl ethers, using 9,10-dicyanoanthrathene (DCA) or dicyanodurene (DCD) as electron acceptor sensitizers, affords the corresponding cyclopropanes resulting from 1-aza-di-π-methane rearrangements via radical cations. In some cases, alternative reactions of these intermediates occur to yield nitriles, dihydroquinolines, dihydronaphthalene derivatives, and cycloaddition products. Some of these products result from reactions via alkene radical-cation intermediates while others arise by pathways involving imine radical-cation intermediates. The yields of products formed in these processes were significantly higher when DCD was used as electron-acceptor sensitizer instead of DCA.
- Armesto, Diego,Ortiz, Maria J.,Agarrabeitia, Antonia R.,Aparicio-Lara, Santiago,Martin-Fontecha, Mar,Liras, Marta,Martinez-Alcazar, M. Paz
-
p. 9397 - 9405
(2007/10/03)
-
- Novel photochemical behaviour of the oximes and hydrazones of β,γ-unsaturated carbonyl compounds
-
A study of the photochemical reactivity of a series of β,γ-unsaturated oximes and hydrazone derivatives under triplet sensitized conditions has been carried out. The oximes 3c, 4a and 4c cyclize to the corresponding dihydroisoxazoles 5c, 6a and 6c while t
- Armesto, Diego,Ramos, Ana,Ortiz, Maria J.,Horspool, William M.,Mancheno, Maria J.,Caballero, Olga,Mayoral, Elena P.
-
p. 1535 - 1541
(2007/10/03)
-
- Unexpected oxadi-π-methane rearrangement of β,γ-unsaturated aldehydes
-
The oxadi-π-methane rearrangement (ODPM) is considered to represent the normal photochemical behavior of β,γ-unsaturated ketones in the triplet excited π,π* state. However, the usual photoreactivity reported for the majority of β,γ-unsaturated aldehydes i
- Armesto, Diego,Ortiz, Maria J.,Romano, Santiago,Agarrabeitia, Antonia R.,Gallego, Mar G.,Ramos, Ana
-
p. 1459 - 1466
(2007/10/03)
-
- Chemically Efficient Aza-Di-?-Methane Photoreactivity with Novel Stable Derivatives of β,γ-Unsaturated Carbonyl Compounds
-
The syntheses of new stable derivatives of β,γ-unsaturated carbonyl compounds such as 2,2-dimethyl-4,4-diphenylbut-3-enal 6 and 3,3-dimethyl-5,5-diphenylpent-4-en-2-one 7 are described.The majority of these derivatives undergo efficient aza-di-?-methane r
- Armesto, Diego,Horspool, William M.,Mancheno, Maria J.,Ortiz, Maria J.
-
p. 2325 - 2330
(2007/10/02)
-
- Extension of the Aza-di-?-methane Reaction to Stable Derivatives. Photochemical Cyclization of β,γ-Unsaturated Oxime Acetates
-
The successful sensitized photochemical conversion of oxime acetates of some β,γ-unsaturated aldehydes and of one ketone into cyclopropane derivatives by the aza-di-?-methane (ADPM) rearrangement has been carried out.Thus, for example, the acetophenone-se
- Armesto, Diego,Horspool, William M.,Langa, Fernando,Ramos, Ana
-
p. 223 - 228
(2007/10/02)
-
- The Aza-di-?-methane Rearrangement of Stable Derivatives of 2,2-Dimethyl-4,4-diphenylbut-3-enal
-
The sensitised irradiations of the semicarbazone (7a), the benzoylhydrazone (7b), and the oxime benzoate (7c) of 2,2-dimethyl-4,4-diphenylbut-3-enal afford the corresponding derivatives of 2,2-dimethylcyclopropanecarbaldehyde (8a-c) in good yield by an az
- Armesto, Diego,Horspool, William M.,Mancheno, Maria J.,Ortiz, Maria J.
-
p. 2348 - 2349
(2007/10/02)
-
- Intramolecular Electron Transfer in the Novel Photoreaction of some β,γ-Unsaturated Oxime-Boron Trifluoride Complexes. A New Synthetic Path to Dihydroisoxazoles
-
β,γ-Unsaturated oximes are photochemically reactive in benzene solution when irradiated in the presence of boron trifluoride-diethyl ether; typically 2,2-dimethyl-4,4-diphenylbut-3-enal oxime affords a low yield of 2,2-diphenyl-3,3-dimethylcyclopropanecar
- Armesto, Diego,Barnes, John C.,Horspool, William M.,Langa, Fernando
-
p. 123 - 125
(2007/10/02)
-
- The Aza-di-?-methane Rearrangement of 1-Aryl-4,4-dimethyl-6,6-diphenyl-2-azahexa-2,5-dienes. The Influence of Substituents on the N-Benzyl Group
-
The acetophenone-sensitised irradiation of a series of 1-aryl-4,4-dimethyl-6,6-diphenyl-2-azahexa-2,5-dienes has been carried out.All undergo an aza-di-?-methane rearrangement to yield a cyclopropylimine.The determination of the quantum yields for the rearrangement showed a dependence on the nature of the substituents on the N-benzyl group and the reaction is most efficient with electron-withdrawing substituents.The linear relationship between log φ and ?+ suggests that there is an homoconjugative interaction between the benzyl group and the nitrogen ione-pair.
- Armesto, Diego,Horspool, William M.,Langa, Fernando
-
p. 903 - 906
(2007/10/02)
-
- The Aza-di-?-methane Rearrangement of O-Acetyl 2,2-Dimethyl-4,4-diphenylbut-3-enal Oxime
-
The photochemical reaction of O-acetyl 2,2-dimethyl-4,4-diphenylbut-3-enal oxime is described: the reaction yields two cyclopropane derivatives, O-acetyl 3,3-dimethyl-2,2-diphenylcyclopropane carboxaldehyde oxime as the primary photoproduct, formed by an
- Armesto, Diego,Horspool, William M.,Langa, Fernando
-
p. 1874 - 1875
(2007/10/02)
-
- Substitution Effects on the Aza-di-?-methane Rearrangement of Imines
-
The u.v. irradiation of several 1-aryl derivatives of 3,3-dimethyl-5,5-diphenyl-1-azapenta-1,4-diene has been carried out.All of them undergo the aza-di-?-methane rearrangement and yield a cyclopropylimine.The influence of substituents on the 1-aryl group has given support for the proposal that imines with a low ionization potential are less efficient at undergoing the aza-di-?-methane process than imines with a higher ionization potential.This was demonstrated in a quantitative fashion.The involvement of an electron-transfer process in the reaction is discussed.
- Armesto, Diego,Horspool, William M.,Langa, Fernando,Perez-Ossorio, Rafael
-
p. 1039 - 1042
(2007/10/02)
-
- The Synthesis and Photochemical Reactivity of β,γ-Unsaturated Imines. An Aza-di-?-methane Rearrangement of 1-Aza-penta-1,5-dienes.
-
The synthesis of imines of 2,2-dimethyl-4,4-diphenylbut-3-enal is described.The photochemical reactivity of these imines is interpreted in terms of an aza-di-?-methane process.After hydrolysis the reaction yields 2,2-dimethyl-3,3-diphenylcyclopropanecarbo
- Armesto, Diego,Horspool, William M.,Martin, Juan-Antonio F.,Perez-Ossorio, Rafael
-
p. 631 - 649
(2007/10/02)
-
- A NOVEL AZA-DI-?-METHANE REARRANGEMENT THE PHOTOREACTION OF 4,4-DIMETHYL-1,6,6-TRIPHENYL-2-AZA-HEXA-2,5-DIENE
-
The synthesis and the novel photochemical aza-di-?-methane reaction of 4,4-dimethyl-1,6,6-triphenyl-2-aza-hexa-2,5-diene are described.
- Armesto, Diego,Martin, Juan Antonio F.,Perez-Ossorio, Rafael
-
p. 2149 - 2152
(2007/10/02)
-