Photoaddition reactions of chromone

Hanifin, J. W.; Cohen, Elliott

doi:10.1021/ja01044a030

Cited by 46 publications

(19 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We evaluated three reactions, which are excellent benchmarks and well established in the literature ( Table 1). The first reaction was cycloaddition of cyclopentene 1 with cyclohexenone 2 to afford cyclobutane 3 [12]. The conversion after 50 min was 30% with a 17% yield.…”

Section: Resultsmentioning

confidence: 99%

Development of a Photochemical Microfluidics Platform

Pimparkar¹,

Yen²,

Goodell³

et al. 2011

J Flow Chem

View full text Add to dashboard Cite

In an effort to utilize microfluidics to enable photochemistry, we have devised a method for fabrication of devices with UV-transmissive glass. The photochemical device is successfully incorporated into a system utilizing high-pressure capillary mercury lamps and cooling system. We have demonstrated the ability to carry out photochemical transformations with substantial rate acceleration. Furthermore, we highlight the ability to carry out analytical-scale reactions on a pulse flow automated system while modulating wavelength and residence time to identify optimal photochemical reaction conditions. The analytical conditions were also successfully converted to continuous-flow preparative scale.

show abstract

Section: Resultsmentioning

confidence: 99%

Development of a Photochemical Microfluidics Platform

Pimparkar¹,

Yen²,

Goodell³

et al. 2011

J Flow Chem

View full text Add to dashboard Cite

show abstract

“…The question of whether the biradical intermediate is formed by initial bond formation at C, or Cp is not well resolved, although there is evidence that the initial bond formation can be at C, or Cp, depending upon the structure of enone and alkene involved (ref. 6; see also refs. 1 a and 1 d).…”

Section: Introductionmentioning

confidence: 95%

Surface photochemistry: silica gel as a medium for photochemical cycloaddition of enones to aliene

Dave¹,

Farwaha²,

Mayo³

et al. 1985

Can. J. Chem.

View full text Add to dashboard Cite

The photocycloaddition of allene to the steroidal enone 1a, normally occurring from the (less hindered) α side, has been directed in part to the (more hindered) β side by adsorption on the surface of silica gel. For a series of cyclic enone–allene photocycloadditions it is shown that the normally favored formation of the β,γ-regioisomeric adduct in homogeneous systems can be shifted to favor the γ,δ adduct on a silica gel surface.

show abstract

“…From the location of the 0-0 band of the phosphorescence spectrum of chromone in 2-methyltetrahydrofuran glass at 77 K, its triplet energy (ET) is measured to be 75.1 kcal/mol (14). Thus chromone is not expected to be an efficient quencher of the triplets of benzophenone (ET = 69 kcal/mol (24)) or p-methoxyacetophenone (ET = 72 kcal/mol (24) [CHROMONE], mM mone at 0-5 mM in benzene, its effect on the decay of benzophenone and p-methoxyacetophenone triplet was studied.…”

Section: Triplet State Photophysical Propertiesmentioning

confidence: 99%

“…It is of interest to know if a similar situation prevails at room temperature and manifests itself in the photophysical and photochemical behavior of the triplet in fluid solutions. Second, chromone has been shown to undergo facile photoaddition reactions in which olefins or acetylenes are added along the ene double bond and, in some cases, at the carbonyl group (13,14). The products of coupling of radicals derived from hydrogen abstraction are also observed (14).…”

Section: Introductionmentioning

confidence: 99%

“…Second, chromone has been shown to undergo facile photoaddition reactions in which olefins or acetylenes are added along the ene double bond and, in some cases, at the carbonyl group (13,14). The products of coupling of radicals derived from hydrogen abstraction are also observed (14). The sustained interest in the photocycloaddition of chromone is borne out by the fact that it has formed the subject of a recent theoretical study (15).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reactivity and photophysical behavior of chromone triplet. A laser flash photolysis study

Rajadurai¹,

Das²

1987

Can. J. Chem.

View full text Add to dashboard Cite

. Can. J. Chem. 65, 2277 (1987). The chromone triplet ( A: , , = 620 nm, E :, , = 2.5 X lo3 M-' cm-' in acetonitrile) is produced in quantitative yields upon 308-or 337.1-nm laser pulse excitation and is characterized by submicrosecond lifetimes in solutions at room temperature. ' The short-lived nature of the triplet is attributable to intrinsically fast TI -SO intersystem crossing, nearly diffusion-limited self-quenching, and facile interactions with solvents in the form of charge and hydrogen-atom transfer. The unusually high self-quenching rate constants, (0.9-4.0) X lo9 M-Is-', are related in a major part to the presence of the ene double bond at which the photocycloaddition of the triplet may occur; this is supported by large bimolecular rate constants (k:) observed for chromone triplet quenching by various alkene derivatives. Although, based on low-temperature photophysical behaviors, the lowest triplet state of chromone in polar solvents is expected to be of reduced I Z , + character, the reactivity of the triplet toward hydrogen donors is very pronounced in acetonitrile (for example, k : = 1.7 x lo9 and 7.4 x lo6 M-' s-' for tri-n-butylstannane and 2-propanol, respectively). Carbon tetrachloride and benzene prove to be facile quenchers of chromone triplet; the quenching interactions probably involve charge transfer, the carbonyl triplet acting as a donor and an acceptor, respectively. The electrophilic role of chromone triplet in the quenching by benzene derivatives is supported by a good correlation between k : and quencher oxidation potential. Utilisant une excitation par laser pulst a 308 ou 337,l nm, on a produit le triplet de la chromone (A: , , = 620 nm; EL,, = 2,5 x lo3 M-' cm-I, dans l'acttonitrile) et on l'a caracttrist, en solutions, a la temptrature ambiante, en faisant appel a des temps de demi-vie plus courts que les microsecondes. On attribue les temps de demi-vie trts courts du triplet i un passage intersysttme TI -So qui est intrinstquement rapide, a un auto-pitgeage qui est pratiquement limit6 par la diffusion ainsi qu'a des interactions faciles avec les solvants sous la forme de transfert de charges et d'atomes d'hydrogknes. On a ttabli que les constantes de vitesses d'auto-pitgeage qui sont inhabituellement ClevCes, (0,9-4,O) X lo9 M -I s-', sont principalement reliCes i la prtsence de la double liaison tne a partir de laquelle la photocycloaddition du triplet peut se produire; cette conclusion est supportte par les constantes de vitesses bimolCculaires tlevCes (ki) qui ont t t t observte pour le pitgeage du triplet de la chromone par divers dtrivts des alcknes. M&me si, sur la base des comportements photophysiques ii basses temperatures, on s'attend a ce que le caracttre n,n* de 1'Ctat triplet le plus bas de la chromone soit rtduit dans les solvants polaires, la rtactivitC du tri let vis-a-vis des donneurs d7hydrogtne est t d s pmnoncee dans I'acCtonitrile (par exemple, k : = 1,7 x lo9 et 7,4 x i06 M-' s-Prespectivement pour le tri-n-butylstannane et le propanol-2). Le tttrachlorure ...

show abstract

Photoaddition reactions of chromone

Cited by 46 publications

References 0 publications

Development of a Photochemical Microfluidics Platform

Development of a Photochemical Microfluidics Platform

Surface photochemistry: silica gel as a medium for photochemical cycloaddition of enones to aliene

Reactivity and photophysical behavior of chromone triplet. A laser flash photolysis study

Contact Info

Product

Resources

About