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Tesi etd-02192010-191218


Tipo di tesi
Tesi di dottorato di ricerca
Autore
CHECCHIA, LORENZO
URN
etd-02192010-191218
Titolo
Synthetic applications of glycal-derived allyl epoxides and aziridines. Synthesis, regio- and stereoselectivity of corresponding carba analogous epoxides in nucleophilic addition reactions.
Settore scientifico disciplinare
CHIM/06
Corso di studi
SCIENZA DEL FARMACO E DELLE SOSTANZE BIOATTIVE
Relatori
tutor Prof. Crotti, Paolo
Parole chiave
  • 4-amino oligosaccharides
  • allyl-aziridines
  • allyl-epoxides
  • carba analogs
  • carbaoligosaccharides
  • carbasugars
  • dihydroxylation
  • glycosylation
  • unsaturated oligosaccharides
Data inizio appello
23/03/2010
Consultabilità
Parziale
Data di rilascio
23/03/2050
Riassunto
This thesis deals with the reactivity and synthetic use of glycal-derived allyl epoxides, allyl aziridines and of the new corresponding carba analogs.
In particular, the complete substrate-dependent O-glycosilation process previously found in O-glycosilation of alcohols by epoxide 2.1β and N-nosyl aziridine 2.3α was adapted in a reiterative version for the construction of 2,3-unsaturated-1,6-oligosaccharides, also bearing a free amino group at C(4) carbon. Subsequent completely stereoselective dihydroxylation afforded corresponding fully substituted 1,6-oligosaccharides.
The reaction of N-mesyl substituted allyl aziridines 2.2α,β derived from D-allal and D-galactal with N-, S- and C-nucleophiles indicated that the occurrence of an oxirane oxygen-nucleophile coordination can modify the commonly observed anti-1,2-regio- and stereoselectivity into syn-1,4-regio- and stereoselectivity with the obtainment of corresponding syn-1,4-addition products.
Epoxides 6.14α and 6.14β, the carba analogs of glycal-derived epoxides 2.1α and 2.1β were synthesized and their regio- and stereochemical behaviour examined, particularly with O-nucleophiles. Whereas epoxide 6.14β turned out to give highly or completely anti-1,2-regio- and stereoselective addition reactions, epoxide 6.14α showed a high 1,4-regioselectivity which makes this epoxide an effective candidate for the synthesis of carbaoligosaccharides.
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