Crystal structure of methyl 3,4-di-O-benzyl-2-deoxy-2-C-nitromethyl-α-D-arabinopyranoside, C21H25NO6

Abstract

C21H25NO6, monoclinic, P1211 (no. 4), a = 9.475(1) A, b = 7.1064(5) A, c = 15.048(2) A, = 101.234(9)°, V = 993.8 A, Z = 2, Rgt(F) = 0.032, wRref(F) = 0.083, T = 210 K. Source of material The title compound was synthesized by radical addition of nitromethane to di-O-benzyl-D-arabinal in the presence of cerium(IV) ammonium nitrate (CAN) [1]. The deprotonation of the CH-acidic precursor with potassium hydroxide prior to oxidation was important, which facilitated the radical generation remarkably. After isolation of the pure arabino isomer by column chromatography (cyclohexane/ethyl acetate 6:1), the product (50 mg) was mixed with ethyl acetate (2 ml) and hexane (1 ml), and toluene (2 ml) was added slowly at room temperature until a clear solution resulted. Colorless single crystals were obtained after slowly volatilizing the solvents at room temperature for four days. Experimental details All of the hydrogen atoms were located from the difference fourier map. One of the oxygen atoms (O6) is disordered over two sides. Using a free variable the SOFs were refined to give a ratio of 0.6 : 0.4.