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Titolo:
Self-sensitized diastereodifferentiating Z-E photoisomerization of 3-, 4-,and 5-benzoyloxycyclooctenes: Intra- versus intermolecular photosensitization
Autore:
Matsuyama, K; Inoue, T; Inoue, Y;
Indirizzi:
JST, ERATO, Inoue Photochirogenesis Project, Toyonaka, Osaka 5650085, Japan JST Toyonaka Osaka Japan 5650085 Project, Toyonaka, Osaka 5650085, Japan
Titolo Testata:
SYNTHESIS-STUTTGART
fascicolo: 8, , anno: 2001,
pagine: 1167 - 1174
SICI:
0039-7881(2001):8<1167:SDZPO3>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
ASYMMETRIC PHOTOCHEMISTRY; ENANTIODIFFERENTIATING PHOTOISOMERIZATION; PRODUCT CHIRALITY; AROMATIC ESTERS; CYCLOOCTENE; BENZENEPOLYCARBOXYLATES;
Keywords:
bcyclooctene; diastereoselectivity; isomerization; photochemistryfgb; self-sensitization;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Physical, Chemical & Earth Sciences
Citazioni:
38
Recensione:
Indirizzi per estratti:
Indirizzo: Inoue, Y JST, ERATO, Inoue Photochirogenesis Project, 4-6-3 Kamishinden, Toyonaka, Osaka 5650085, Japan JST 4-6-3 Kamishinden Toyonaka Osaka Japan 5650085 5650085, Japan
Citazione:
K. Matsuyama et al., "Self-sensitized diastereodifferentiating Z-E photoisomerization of 3-, 4-,and 5-benzoyloxycyclooctenes: Intra- versus intermolecular photosensitization", SYNTHESIS-S, (8), 2001, pp. 1167-1174

Abstract

Upon irradiation at 254 nm, (Z)-3-, 4-, and 5-benzoy loxycyclooctenes (1Z-3Z) efficiently isomerized through intra-and/or intermolecular sensitization to the corresponding diastereomeric E-isomers (1E-3E) with low to moderate diastereomeric ex cesses (de's) of up to 43 %. The major diastereomer produced from 1Z was switched from (1R*,3R*)-1E (26% de) to (1R*,3S*;)-1E (-11% de) by simply increasing the substrate concentration from 1 mM to 50 mM. This unusual switching of product chirality is attributed to the opposite diastereoselectivities for intra- and intermolecular photosensitization. In contrast, 2Z and 3Z did not show such switching behavior, but consistently gave a single diastereomer of up to 9 % and 43 % de, respectively, over a wide range of substrate concentrations (0.04-50 mM), for which totally different mechanisms are responsible. Thus, the intra- and intermolecular sensitizations of 2Z exhibit the same diastereoselectivity, while only the intermolecular sensitization of 3Z can occur as a result of the hindered intramolecular approach of the benzoate substituent to the cyclooctene moiety.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/04/20 alle ore 03:04:18