• Rapid Communication in Photoscience
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• v.1 no.1
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• pp.17-18
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• 2012

Photoaddition reactions between 1,2-dicarbonyl compounds and silyl enol ethers in acetonitrile and benzene were explored. Irradiation of acetonitrile or benzene solutions containing 1,2-diketone, acenaphthalquinone, phenanthrene-quinone and silyl enol ethers is observed to promote the production of 1,4-dioxenes, oxetanes, and ${\beta}$-hydroxyketone by the [4+2]-cycloadditon, Paterno-Buchi processes, and SET promoted Claisen-type condensation. Among these competitive pathways leading to the generation of each types of products, SET promoted 1,4-dioxene and ${\beta}$-hydroxyketone formation are more favored regardless of solvent polarity.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.629-634
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• 2007

Photochemical reactions of N-methylphthalimide with silyl enol ethers have been explored. Irradiations of phthalimide (1) and cyclic silyl enol ethers (5a-b) are observed to promote formation of photoreduced phthalimides and photoaddition products by sequential SET-desilylation pathways. The photoreaction of phthalimide (1) and acyclic silyl enol ethers (5c-d) leads to produce oxetanes which arise by competitive single electron transfer (SET) and classical 2+2 photocycloaddition (Parteno-Buchi reaction) pathways.

• Bulletin of the Korean Chemical Society
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• v.10 no.3
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• pp.223-226
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• 1989

The chemical reactivity of 5,7-dimethoxycoumarine with adenosine has been calculated by the frontier electron and PPP-Cl MO methods. Results suggest that the major reactivity of the 5,7-dimethoxycoumarin is highest at the carbon-4 (position 4), whereas the electrophilic reactivity is generally spread all over the 5,7-dimethoxycoumarin molecule. These results are consistent with the experimental photoaddition reaction products. The small change of bond orders on excitation does not give enough reactivity to triplet states or the efficient intersystem crossing from $T_1\;to\;S_0$ inhibits photoaddition of 5,7-dimethoxycoumarine to adenosine. Although the relative intensity of the singlet band appears to be considerably higher than the triplet band intensity, its integrated intensity, i.e. oscillator strength, is comparable to that of the 5,7-dimethoxycoumarin and adenosine bands.

• Bulletin of the Korean Chemical Society
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• v.17 no.7
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• pp.577-579
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• 1996

• Bulletin of the Korean Chemical Society
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• v.15 no.4
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• pp.270-272
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• 1994

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1218-1242
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• 2002

Photochemical reactions of aromatic carbonyl compounds with silyl ketene acetals have been explored. Irradiation of acetonitrile or benzene solutions containing aryl aldehydes or ketones in the presence of silyl ketene acetals is observed to promo te formation of ${\beta}-hydroxyester$, 2,2-dioxyoxetane and 3,3-dioxyoxetane products. The ratios of these photoproducts, which arise by competitive single electron transfer (SET) and classical Paterno-Buchi mechanistic pathways, is found to be dependent on the degree of methyl-substitution on the vinyl moieties of the ketene acetals in a manner which reflects expected alkyl substituent effects on the oxidation potentials of these electron rich donors. An analysis of the product distribution arising by irradiation of a solution containing butyrophenone (6) and the silyl ketene acetal 9, derived from methyl isobutyrate, provides an estimate of the rate constants for the competitive Norrish type Ⅱ, SET and Paterno-Buchi processes occuring. Finally, sequences involving silyl ketene acetal-aryl aldehyde or ketone photoaddition followed by 2,2-dioxyoxetane hydrolysis represent useful procedures for Claisen-condensation type, ${\beta}-hydroxyester$ synthesis.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.686-689
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• 1998

Irradiation of 1-(o-allyloxyphenyl)-2-pentamethyldisilanylethyne (2) in methanol yields two 1 : 1 photoaddition products (3 and 4) via silacyclopropene intermediate. Photolysis of (2) with acetone in deaerated methylene chloride yields site specific and regioselective 1: 1 adducts (7 and 8) via silacyclopropene and 1-sila-1,2-propadiene intermediate, respectively.

• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.66-69
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• 1989

Irradiation of solutions of p-quinones and conjugated diyne, 1,4-diphenylbutadiyne, with 350 nm UV light gave the photoproducts such as quinomethane in good yields (70-85%).

• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.988-990
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• 1995

No fluorescence was observed from 1-aryl-4-(pentamethyldisilanyl)buta-1,3-diynes except 1-(1-naphthyl)-4-(pentamethyldisilanyl)buta-1,3-diyne. Irradiation of 1-aryl-4-(pentamethyldisilanyl)buta-1,3-diynes (1) with methanol gives photoaddition products in relatively low yields compared to arylethynyldisilanes which show dual fluorescence. Irradiation of 1 with acetone yields site specific and regioselective 1:1 photoadducts through silacyclopropene intermediates. The triplet excited state of the silacyclopropene reacts with acetone to give addition photoproducts and the triplet energy of the silacyclopropenes lies around 260-286 kJ/mol.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.206-211
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• 1987

The photoreaction of 5,7-dimethoxycoumarin with adenosine has been carried out in a dry film state. The mixture of DMC and adenosine was irradiated with 350 nm UV light and two major products were isolated. The structure was determined by various spectroscopic measurements involving $^{13}C$ nuclear magnetic resonance and fast atom bombardment mass spectrometry. These addition products were produced by covalent bond formation between the pyrone ring at carbon 3 or 4 and the sugar ring moiety of adenosine at carbon 5'.