- Light-induced one-pot synthesis of pyrimidine derivatives from vinyl azides
-
A one-pot procedure for the synthesis of tetrasubstituted dihydropyrimidine and pyrimidine derivatives from α-azidocinnamates was developed. The synthesis is based on the finding that the outcome of LED photolysis of α-azidocinnamates depends on the light wavelength employed. Blue light (455 nm) leads to the formation of 2H-azirines only, but violet light (395 nm), UV-A light (365 nm), or sunlight result in the transformation of the in situ formed 2H-azirines to 1,3-diazabicyclo[3.1.0]hex-3-enes. Under basic catalysis (DBU), the latter were isomerized to 1,6-dihydropyrimidines which were oxidized to pyrimidines using DDQ. A successful use of Cs2CO3 as a base and air as an oxidant was also demonstrated.
- Khoroshilova, Olesya V.,Kinzhalov, Mikhail A.,Nguyen, Tuan K.,Rostovskii, Nikolai V.,Titov, Gleb D.
-
supporting information
p. 4971 - 4982
(2020/07/23)
-
- Methyl 2-aryl-2H-azirine-3-carboxylates as dienophiles
-
Diels-Alder reactions of the methyl 2-aryl-2H-azirine-3-carboxylates 1a and 1b have been investigated in order to determine the stereoselectivity and regioselectivity of the reaction. The azirines react with a range of electron rich dienes at room temperature to give Diels-Alder adducts. The reaction leads to the formation of endo-cycloadducts with both cyclic and acyclic dienes; furan Is exceptional in giving an exo-adduct 7. X-Ray crystallography has established the structure 9 of the Diels-Alder adduct formed from the azirine 1a and 1-acetoxybutadiene. The same regioselectivity, in which the more nucleophilic terminus of the diene combines with the carbon atom of the C=N bond, is found in the adducts from several other 1- and 2-substituted dienes. Only isoprene, among the dienes examined, gives a mixture containing the opposite regioisomer 14 as a minor component.
- Alves, M. Jose,Gilchrist, Thomas L.
-
p. 299 - 303
(2007/10/03)
-
- Methyl 2H-azirine-3-carboxylates as dienophiles: Synthesis of methyl 1-azabicyclo[4.1.0]hept-3-ene-6-carboxylates
-
Methyl 2-aryl-2H-azirine-3-carboxylates are good dienophiles. They react with cyclopentadiene, cyclohexa-1,3-diene and 2,3-dimethylbuta-1,3-diene at or below 50°C to give products of [4 + 2]-cycloaddition to the carbon-nitrogen double bond. The cycloaddit
- Bhullar, Pamila,Gilchrist, Thomas L.,Maddocks, Peter
-
p. 271 - 272
(2007/10/03)
-