[N:1]1[CH:6]=[CH:5][CH:4]=[C:3]([C:7](O)=[O:8])[C:2]=1[C:10]1[CH:11]=[N:12][CH:13]=[CH:14][CH:15]=1.C(N(CC)CC)C.[BH4-].[Na+].CO.Cl>O1CCCC1>[OH:8][CH2:7][C:3]1[C:2]([C:10]2[CH:11]=[N:12][CH:13]=[CH:14][CH:15]=2)=[N:1][CH:6]=[CH:5][CH:4]=1To a continually stirred, ice-cold solution of 2,3′-bipyridine-3-carboxylic acid (0.28 g, 1.40 mmole) in dry tetrahydrofuran (10 ml) and triethylamine (0.20 ml, 1.43 mmole) ethyl chloroformate (0.14 ml, 1.46 mmole) was added drop-by-drop over a 30 minute period. The precipitated product was then filtered and washed several times with tetrahyrofuran (3×2 ml). The THF phases were combined, cooled to +10° C., and while stirring under an argon atmosphere, sodium borohydride (0.185 g, 4.9 mmole) was added and then methanol (0.90 ml, 22.2 mmole) was added drop-by-drop over a 1 hour period during which time the temperature increased to 20° C. (Soai et al., 1987). The material was stirred for an additional 1 hour at room temperature. Then, 1N hydrochloric acid was carefully added, the solvent was evaporated under vacuum to 5 ml and washed with dichloromethane (3×5 ml). Sodium carbonate (0.85 g) was added to the aqueous phase, which was then extracted with dichloromethane. The combined fractions were dried with magnesium sulfate and evaporated under vacuum (2 Hg mm, 45° C.) giving a pure product (0.22 g, 84%). 1H-NMR, δ, ppm, 8.71 (1H, dd, J=2.1, 0.6 Hz, C2′-H), 8.55 (1H, dd, J==4.8, 1.5 Hz, C6-H), 8.52 (1H, dd, J=4.8, 1.8 Hz, C6′-H), 7.95 (1H, dd, J=7.8, 1.5 Hz, C4-H), 7.91 (1H, ddd, J=7.8, 2.1, 1.8 Hz, C4′-H), 7.35 (1H, ddd, J=7.8, 4.8, 0.6 Hz, C5′-H), 7.31 (1H, dd, J=7.8, 4.8 Hz, C5-H), 4.58 (2H, s, CH2-O).
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