Lewis acid catalysis of photochemical reactions.  7.  Photodimerization and cross-cycloaddition of cinnamic esters

Lewis, Frederick D.; Quillen, Suzanne L.; Hale, Paul D.; Oxman, Joe D.

doi:10.1021/ja00212a039

Cited by 109 publications

(62 citation statements)

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“…19,20 The furyl acrylates (15) and (16), with a methyl group respectively in an α-position to the carboxylic ester and in an α-position on the furan ring, showed different behaviours. While compound (15) …”

Section: Discussionmentioning

confidence: 99%

“…12 On the other hand, irradiation in methanolic solution did not furnish any cyclodimerization product, giving instead only E-Z isomerization, 13 while irradiation in the presence of BF 3 furnished a mixture of seven immers (Scheme 3). 14,15 However, the application of this methodology to methyl 3,4-dimethoxycinnamate failed. 16 3,4-Dimethoxycinnamic derivatives can be dimerized only in the presence of cyclodextrin.…”

Section: Methodsmentioning

confidence: 99%

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The photochemical dimerization of 3-heteroaryl-acrylates

D’Auria¹,

Emanuele²,

Esposito³

et al. 2002

Arkivoc

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A detailed explanation of the observed photochemical reactivity of 3-heteroaryl-acrylates is furnished on the basis of a comprehensive review of the photochemical dimerizations of this type of compounds. The reactions occurred in the triplet state of the reagents showing good regio-and stereoselectivities. The regioselectivity can be explained assuming that the dimerization reaction is frontier orbitals controlled. The reaction of the triplet state of a reagent with another molecule of the reagent leads to the formation of the most stable biradical. This behavior induces a control in the relative stereochemistry of the two ester functions. The following cyclization occurs in order to obtain the products under kinetic control. This cyclization allows the formation of the most stable isomers.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The photochemical dimerization of 3-heteroaryl-acrylates

D’Auria¹,

Emanuele²,

Esposito³

et al. 2002

Arkivoc

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“…S 0 oscillator strength is approximately half that of the trans form, in agreement with earlier measurements. [1][2][3]10] Femtosecond transient absorption spectra are compared with calculations in Figure 9. The measured spectra (lines) are those of Figure 2 but the bleach contribution has been subtracted so that they now represent the sum of ESA and SE.…”

Section: Discussionmentioning

confidence: 99%

Femtosecond S₃→S₁ Conversion and Structural Reorganisation of trans‐3‐Phenylprop‐2‐enaldehyde and Derivatives in Solution

2005

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Photoinduced excited-state relaxation of trans-3-phenylprop-2-enaldehyde (cinnamaldehyde) and three derivatives was studied in hexane and acetonitrile with the pump-supercontinuum-probe technique. Transient spectra were measured with 50 fs resolution in the range 260-660 nm after S3<--S0 excitation at 288 nm. The early spectra reveal an ultrafast, 0.1-0.5 ps, interchange of intensity between two excited-state absorption (ESA) bands followed by a approximately 3 ps decay of ESA. This behaviour is interpreted with the help of semiempirical calculations, which indicate that the sub-picosecond evolution is consistent with S3-->S1 excited-state relaxation while the picosecond decay should be due to a structural intramolecular rearrangement. The latter may consist of a twist of the phenyl ring and rotation around the C==C bond to a perpendicular conformation which corresponds to the global energy minimum in the S1 state and serves as source for trans and cis isomers in the ground state.

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“…[12] So bençtigte etwa der Zimtsäureester 6 in der [2+ +2]-Photocycloaddition mit cis-2-Buten (20 ¾q.) Dies mag daran liegen, dass die katalytische Wirkung auf die [2+ +2]-Photocycloaddition von 2-Alkenoaten nicht besonders ausgeprägt ist.…”

Section: Introductionunclassified

Chromophoraktivierung von α,β‐ungesättigten Carbonylverbindungen und ihre Anwendung in enantioselektiven Photoreaktionen

2018

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Das erste Gesetz der Photochemie, das auf Theodor von Grotthuß und John W. Draper zurückgeht, besagt, dass nur der Teil des Lichts, der durch Materie absorbiert wird, eine Wirkung hervorruft. Entsprechend lässt sich das Reaktionsverhalten einer chemischen Verbindung steuern, wenn ihr Absorptionsverhalten der Emission der Lichtquelle angepasst wird. Eine chemische Verbindung mit einem Chromophor, der nur bei einer niedrigen Wellenlänge Licht absorbiert, wird durch langwellige Strahlung nicht angeregt. Gelingt es durch eine reversible chemische Modifikation, die photophysikalischen Eigenschaften des Chromophors zu verändern, kann man selektiv diese modifizierte Spezies anregen. Diese Chromophoraktivierung wird in α,β‐ungesättigten Carbonylverbindungen durch Lewis‐Säuren, Brønsted‐Säuren oder die Bildung von Iminiumionen hervorgerufen und kann dazu genutzt werden, Photoreaktionen bei vorgegebener Wellenlänge zu katalysieren. In diesem Kurzaufsatz wird das Konzept der Chromophoraktivierung vorgestellt, und es werden konkrete Anwendungen in der enantioselektiven Katalyse besprochen.

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Lewis acid catalysis of photochemical reactions. 7. Photodimerization and cross-cycloaddition of cinnamic esters

Cited by 109 publications

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The photochemical dimerization of 3-heteroaryl-acrylates

The photochemical dimerization of 3-heteroaryl-acrylates

Femtosecond S₃→S₁ Conversion and Structural Reorganisation of trans‐3‐Phenylprop‐2‐enaldehyde and Derivatives in Solution

Chromophoraktivierung von α,β‐ungesättigten Carbonylverbindungen und ihre Anwendung in enantioselektiven Photoreaktionen

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Lewis acid catalysis of photochemical reactions. 7. Photodimerization and cross-cycloaddition of cinnamic esters

Cited by 109 publications

References 0 publications

The photochemical dimerization of 3-heteroaryl-acrylates

The photochemical dimerization of 3-heteroaryl-acrylates

Femtosecond S3→S1 Conversion and Structural Reorganisation of trans‐3‐Phenylprop‐2‐enaldehyde and Derivatives in Solution

Chromophoraktivierung von α,β‐ungesättigten Carbonylverbindungen und ihre Anwendung in enantioselektiven Photoreaktionen

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Femtosecond S₃→S₁ Conversion and Structural Reorganisation of trans‐3‐Phenylprop‐2‐enaldehyde and Derivatives in Solution