Non-oxidative dimerization of 3,4-dioxygenated cinnamates to aryltetralin lignans.

Botta, Bruno; Iacomacci, Paolo; Vinciguerra, Vittorio; Monache, Giuliano Delle; Gács‐Baitz, Eszter; Botta, Maurizio; Misiti, D.

doi:10.1248/cpb.38.3238

Cited by 13 publications

(2 citation statements)

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“…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. 17 Recently, we found that methoxy-, dimethoxy-, and trimethoxycinnamate esters can be dimerized in acetonitrile both in the presence or in the absence of a triplet sensitizer.…”

Section: Methodsmentioning

confidence: 99%

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: Methodsmentioning

confidence: 99%

The photochemical dimerization of 3-heteroaryl-acrylates

D’Auria¹,

Emanuele²,

Esposito³

et al. 2002

Arkivoc

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“…On the other hand, the irradiation in methanolic solution did not furnish any dimerization product, giving instead only E-Z isomerization [17], while, the irradiation in the presence of BF 3 , furnished a mixture of seven dimers (Scheme 2) [18,19]. However, the application of this methodology to methyl 3,4-dimethoxycinnamate failed [20]. Cyclodextrin was used in order to perform the photochemical dimerization of 3,4-dimethoxycinnamic derivatives [21].…”

Section: Introductionmentioning

confidence: 99%

A DFT Study of the Photochemical Dimerization of Methyl 3-(2-Furyl)acrylate and Allyl Urocanate

D’Auria

2014

Molecules

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A DFT study of the photochemical dimerization of methyl 3-(2-furyl)acrylate is reported. The photochemical reaction gave a mixture of two dimers with high regioselectivity and good stereoselectivity. Calculations showed that benzophenone was able to act as a photosensitizer of the reaction. This compound populated the first excited triplet state of the substrate. The frontier orbitals interaction between LSOMO of the triplet state and HOMO of the ground state accounted for the observed high regioselectivity. Furthermore, the energy of all the possible triplet biradicals has been calculated, showing that the precursor of the main product was the triplet biradical with the lowest energy. The coupling of the atomic coefficients on the radical centres in the biradical intermediates allowed to justify the observed products. The same behavior was observed in the case of the photochemical dimerization of an urocanate ester and in the dimerization of liquid methyl cinnamate.

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