Radical Cyclization Approach to Cyclonucleosides (Articolo in rivista)

Type
Label
  • Radical Cyclization Approach to Cyclonucleosides (Articolo in rivista) (literal)
Anno
  • 2005-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1002/ejoc.200500398 (literal)
Alternative label
  • Navacchia, M. L.; Manetto, A.; Montevecchi, P. C.; Chatgilialoglu, C. (2005)
    Radical Cyclization Approach to Cyclonucleosides
    in European journal of inorganic chemistry (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Navacchia, M. L.; Manetto, A.; Montevecchi, P. C.; Chatgilialoglu, C. (literal)
Pagina inizio
  • 4640 (literal)
Pagina fine
  • 4648 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • -- (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo
  • 21 (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Navacchia, M. L.; Manetto, A.; Chatgilialoglu, C.: ISOF, Consiglio Nazionale delle Ricerche, Via P. Godetti 101, 40129 Bologna, Italy Montevecchi, P. C.: Dipartimento di Chimica Organica \"A. Mangini\", Università di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy (literal)
Titolo
  • Radical Cyclization Approach to Cyclonucleosides (literal)
Abstract
  • Efficient methodologies based on consecutive radical reactions for the preparation of cyclonucleosides 5 and 13 are reported. The reactions were performed on modified thymidine and 2?-deoxyadenosine substrates using (TMS)3SiH as the reducing agent. The protected 5?-carbaldehyde 3 afforded the cyclonucleoside 4 in 85 % yield and in a diastereoisomeric ratio 4a/4b = 3:7. The mono-desilylation at the 5?-O position of these cyclonucleosides has been successfully achieved by UV irradiation affording quantitatively derivatives 5a and 5b. The protected 5?-carbaldehyde 10 afforded the cyclonucleoside 12 in 70-75 % yield as a single diastereoisomer (5?R) either in deoxygenated solution, followed by in situ oxidation of the reaction mixture by chloranil, or in aerobic conditions. The photochemical 5?-O-desilylation of 12 has been obtained in 56 % yield affording the cyclopurine 13. The reaction mechanisms have been studied in some detail using a variant of the radical clock methodology. The C5? radical 6 or 15, generated by addition of the (TMS)3Si· radical to the corresponding aldehyde, undergoes a 6-exo-trig cyclization on the base moiety prior to termination. The rate constants for both 6-exo-trig radical cyclizations have been estimated to be close to 105 s-1 at 86 °C, the cyclization on the purine moiety being 4-5 times faster than that on the pyrimidine group. (literal)
Prodotto di
Autore CNR
Insieme di parole chiave

Incoming links:


Prodotto
Autore CNR di
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#rivistaDi
Insieme di parole chiave di
data.CNR.it