The Structure of N‐(1‐Deoxy‐β‐D‐fructopyranos‐1‐yl)‐L‐proline Monohydrate (“D‐Fructose‐L‐proline”) and N‐(1,6‐Dideoxy‐α‐L‐fructofuranos‐1‐yl)‐L‐proline (“L‐Rhamnulose‐L‐proline”)

Abstract

D‐Fructose‐L‐proline is an important food‐related precursor for thermally generated aromas. We report the crystal structure analysis of N‐(1‐deoxy‐β‐D‐fructopyranos‐1‐yl)‐L‐proline monohydrate (1) and its analog, N‐(1,6‐dideoxy‐α‐L‐fructofuranos‐1‐yl)‐L‐proline (“L‐rhamnulose‐L‐proline”) (2). The carbohydrate rings adopt the normal 2C5 pyranose chair conformation in 1 and the 5E furanose envelope conformation in 2. Bond lengths and valence angles in 1 and 2 compare well with the average values from related pyranose and furanose structures. All hydroxyl and carboxyl oxygen atoms, ammonium groups, and the water molecule in 1 are involved in an extensive hydrogen bonding, which forms a system of infinite chains with attached side chains. The hydrogen bonding network in 2 is an infinite three‐dimensional network and is represented by separate short finite and infinite chains.