R6sum6 -L'utilisation du chauffage micro-on&, en utilisant le graphite comme support, a permis de r&liser la rdaction de r&ro-Diels-Alder, sur les adduits 10-16. La rdaction est effectude en quelques minutes, fi pression atmosphdrique, sans solvant. © Acaddmie des sciences/Elsevier, Paris r4tro-Diels-Alder / micro-ondes / graphite Abstract -Retro-Diels-Alder reactions under microwave radiation. By using microwave heating with graphite as support, it is possible to realize in a few minutes at atmospheric pressure, without solvent, retro-Diels-Alder reaction,'; with adducts 10-16. © AcadSmie des sciences/Elsevier, Paris retro-Diels-Alder / microwaves / graphite
Abridged English Version
Retro-Diels-Alder reactions carried out from adducts containing a rest of anthracene have been studied. The authors use flash thermolysis at temperatures higher than 550 °C [14][15][16][17] or by heating at 230 °C/20 mmHg [18], to avoid decomposition of adducts. The effect of substituents in cycloadducts of anthracene on the retro-Diels-Alder speed has been approached in solution at 200 °C in diethyl ether [19,20].
In our study, we suggest a new methodology, which consist,,; in carrying out retro-Diels-Alder reactions by using microwave heating, with graphite as support. We have studied a methodology already described recently [10,11], in the synthesis of these adduct~,:. The obtained adducts from 10 to 16 are gathered in table I.
Next, we have carried out retro-Diels-Alder reactions, without any solvent, by using microwave heating with graphite as support. Adducts 10-16 have been heated with a 90 or 120 W power (table I1), with 3 to 5 microwave irradiations for a minute, after letting the system cool for one minute; following irradiation we were able to notice almost complete reactions. Indeed, the advancement of the reactions is comprised between 79 and 95 %. This new methodolo D" of the chemically supported reactions involving graphite, combines a strong thermal effect due to graphite/microwave interaction and an effect of confinement of reagents on support due to absorption and/or intercalation phenomena.
Prdsentd par Francois MATHEY.