- Divergent synthesis of two precursors of 3′-homo-2′-deoxy- and 2′-homo-3′-deoxy-carbocyclic nucleosides
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Aminocyclopentanedimethanols 4 and 5, which are of interest for the synthesis of higher homologues of 2′-deoxy- and 3′-deoxycarbonucleosides, respectively, were efficiently prepared by divergent routes starting from (±)-exo-bicyclo[2.2.1]hept-5-ene-2-carbaldehyde. In the key step, ammonolysis of the common intermediate (±)-(1β,3β,4α)-4-benzoyloxymethyl-1,3- cyclopentanedicarboxylic anhydride and subsequent esterification afford near-equimolar amounts of two easily separable isomeric carbamoyl esters.
- Blanco, José M,Fernández, Franco,García-Mera, Xerardo,Rodríguez-Borges, José E
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- Controlled molecular design of ether- and ester-bridged norbornenes and their ring-opening metathesis polymerizations
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A series of functionalized polynorbornenes containing pendent ether- or ester-bridged poly(aromatic ether) chains were prepared. The ether-bridged norbornene complex was synthesized via cyclopentadienyliron-mediated nucleophilic aromatic substitution reactions. This methodology, combined with that of dicyclohexylcarbodiimidemediated coupling, allowed for the formation of novel oligomeric aryl ether and ester substituted norbornene complexes. Photolytic demetallation gave the monomers in good yields. Structural identification of the exo and endo isomers of both the metallated and demetallated norbornene derivatives was accomplished using HH and CH COSY NMR techniques. Ring-opening metathesis polymerization (ROMP) of these monomers using RuCl3(hydrate) and (Cy3P)2Cl2Ru=CHPh allowed for the preparation of the functionalized polynorbornenes. Thermal analysis of the resulting polymeric materials demonstrated greater thermal stability as the number of aryl ether groups increased.
- Abd-El-Aziz, Alaa S.,Edel, Andrea L.,May, Leslie J.,Epp, Karen M.,Hutton, Harold M.
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p. 1797 - 1809
(2007/10/03)
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