Search results for "Cyclohexadienes"
showing 3 items of 3 documents
Mechanism of triplet photosensitized Diels-Alder Reaction between indoles and cyclohexadienes: theoretical support for an adiabatic pathway.
2006
Diels-Alder reactions between indoles (InHs) and 1,3-cyclohexadienes (CHDs) were achieved by using aromatic ketones as photosensitizers. For instance, irradiation of deaerated dichloromethane solutions containing benzoylthiophene (BT, 1 mM), indole (20 mM), and phellandrene (40 mM), in the presence of an acylating agent, led to the N-acetylated Diels-Alder cycloadduct in 46% yield (endo:exo ratio of 1.8:1). Energy transfer from the BT triplet to the CHD gave rise to diene dimers as byproducts. Several combinations of CHDs, InHs, and aromatic ketones were tested; the Diels-Alder reaction was found to be a general process, except when the indole nucleus was substituted at position 2 or 7 and …
Diels-Alder reaction between indoles and cyclohexadienes photocatalyzed by a (thia)pyrylium salt
2007
"Thiapyrylium salt 1 is an efficient photocatalyst in the Diels-Alder reaction between indoles (InHs) and 1,3-cyclohexadienes (CHDs). For instance, irradiation of deaerated dichloromethane solutions containing 1 (1 mM), indole (20 mM) and cyclohexadiene (40 mM), in the presence of an acylating agent, led to the Diels-Alder cycloadduct in 62% yield (endo:exo ratio of 1.8:1). Taking into account the very high intersystem crossing yield (Φisc = 0.97) of thiapyrylium salt 1, involvement of its triplet excited state in this Diels-Alder reaction has been studied using steadystate and time-resolved experiments; the results are compared with those previously obtained for pyrylium salts, which exhib…
Synthesis of new polymers via Diels–Alder reaction. III. Biscyclohexadienephthalimides as dienes
1993
Difunctional cyclohexadienes with dihydrophthalimide central unitsand phenyl side groups to increase solubility are used as bisdienes in repetitive Diels-Alder polyadditions with bis(4-(1,2,4,-triazoline-3,5-dione-4-yl)phenyl)methane as a difunctional dienophile. The polymers show good solubility in CH 2 Cl 2 and CHCl 3 . Non-stoichiometric Diels-Alder polyaddition with slight excess of the bistriazolinedione provides the possibility of synthesizing telechelics with highly reactive triazolinedione end groups