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A mixture of 10 (0.43 g, 1.04 mmol) and 6-chloropurine (0.24 g, 1.56 mmol) in 17 mL acetonitrile was cooled to 0° C. and a 1.8 M toluene solution of diethylaluminum chloride (0.59 mL, 1.06 mmol) was added over 1 minute. Stirring was continued at 0° C. for 5 minutes and at 25° C. for 10 minutes. The reaction mixture was quenched by pouring into a mixture of 20 mL dichloromethane and 10 mL saturated NaHCO3. The organic phase was dried (MgSO4) and concentrated in vacuo. The residue was flash chromatographed with 9:1 hexane/ethyl acetate followed by 4:1 hexane/ethyl acetate. Solvent removal gave a 1:1 α/β anomeric mixture: yield 0.315 g (59%); FAB MS 509 (M+H)+ ; 1H NMR (CDCl3) of β anomer, δ 8.7 (s, 1, H-2), 8.45 (s, 1, H-8), 7.7 (m, 4, ArH), 7.4 (m, 6, ArH), 6.27 (m, 1, 7'-H), 3.95 (m, 1, 5'-H), 3.85 (m, 2, 4'-H, 5'-H), 2.45 (m, 2, 2'-H's), 2.25 (m, 1, 3'-H), 1.85 (m, 1, 3'-H), 1.1 (s, 9, t-butyl).

1. customThe reaction mixture was quenched
2. additionby pouring into a mixture of 20 mL dichloromethane and 10 mL saturated NaHCO3
3. dry with materialThe organic phase was dried (MgSO4)
4. concentrationconcentrated in vacuo
5. customchromatographed with 9:1 hexane/ethyl acetate
6. customSolvent removal
7. customgave a 1:1 α/β anomeric mixture