Alogliptin and its benzoate salt

Abstract

The crystal structure of the free base of the antidiabetic drug alogliptin [systematic name: 2-({6-[(3R)-3-aminopiperidin-1-yl]-3-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-yl}methyl)benzonitrile], C18H21N5O2, displays a two-dimensional N—H...O hydrogen-bonded network. It contains two independent molecules, which have the same conformation but differ in their hydrogen-bond connectivity. In the crystal structure of the benzoate salt (systematic name: (3R)-1-{3-[(2-cyanophenyl)methyl]-1-methyl-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-yl}piperidin-3-aminium benzoate), C18H22N5O2+·C7H5O2−, the NH3+group of the cation is engaged in three intermolecular N—H...O hydrogen bonds to yield a hydrogen-bonded layer structure. The benzoate salt and the free base differ fundamentally in the conformations of their alogliptin moieties.