Synthesis of N,O- homonucleosides with high conformational freedom

2009 ARKIVOC  
The 1,3-dipolar cycloaddition of vinyloxymethyl thymine with different nitrones has been exploited for the preparation of N,O-homonucleosides where the oxymethylene tether replaces the aminal linkage between the sugar moiety and the nucleobase Issue in Honor of Prof Nicolò Vivona ARKIVOC 2009 (viii) 168-176 coupling of 7 with silylated thymine, followed by treatment with sodium periodate and sodium bicarbonate, afforded the dipolarophile 9 with a yield of 70%. Scheme 1. (a) NaBH 4 , EtOH dry,
more » ... hylencarbonate, reflux, 12h; (b) CH 2 O, CH 2 Cl 2 , HCl g , 5°C, 2h; (c) BSA, thymine, TMSOTf, CH 3 CN dry, r.t., 12h; (d) NaIO 4 , NaHCO 3 , MeOH, r.t., 30', then dioxane, 80°C, 2h. A study of the optimal conditions for the 1,3-dipolar cycloaddition of compound 9 was carried out by employing nitrones 10-12. (Scheme 2, Table 1 , Entry 1-6). Scheme 2. Cycloaddition reactions.
doi:10.3998/ark.5550190.0010.814 fatcat:tfncu76oqjckhpe2wht3zdqoyu