Crystal structure of the acyclic form of 1-de­oxy-1-[(4-methoxyphenyl)(methyl)amino]-d-fructose

The title compound, C(14)H(21)NO(6), (I), crystallizes exclusively in the acyclic keto form. In solution of (I), the acyclic tautomer represents only 10% of the population in equilibrium, with the other 90% consisting of β-pyran­ose, β-furan­ose, α-pyran­ose, and α-furan­ose cyclic forms. The carbohydrate chain in (I) has a zigzag conformation and the aromatic amine group has a transitional sp (2)/sp (3) geometry. Bond lengths and valence angles in the carbohydrate portion compare well with the average values for related acyclic polyol structures. All of the hydroxyl groups are involved in inter­molecular hydrogen bonding and form a two-dimensional network of infinite chains, which are inter­linked by intra­molecular hydrogen bonds and organized into R (8) (8)(16) homodromic ring patterns. A comparative Hirshfeld surfaces analysis of (I) and four other 1-amino-1-de­oxy-d-fructose derivatives suggests the balance of hydro­philic/hydro­phobic inter­actions plays a role in the crystal packing, favoring the acyclic isomer.