Crystal structure and Hirshfeld surface analysis of the hydrochloride salt of 8-{4-[(6-phenylpyridin-3-yl)methyl]piperazin-1-yl}-3,4-dihydroquinolin-2(1H)-one

Abstract

The amine 8-{4-[(6-phenylpyridin-3-yl)methyl]piperazin-1-yl}-3,4-dihydroquinolin-2(1H)-one was crystallized as the hydrochloride salt, 4-(2-oxo-1,2,3,4-tetrahydroquinolin-8-yl)-1-[(6-phenylpyridin-3-yl)methyl]piperazin-1-ium chloride, C25H27N4 +·Cl− (I·HCl). The conformation of the organic cation is half-moon in shape enclosing the chloride anion. The piperidine ring of the 3,4-dihydroquinolin-2(1H)-one moiety has a screw-boat conformation, while the piperazine ring has a chair conformation. In the biaryl group, the pyridine ring is inclined to the phenyl ring by 40.17 (7) and by 36.86 (8)° to the aromatic ring of the quinoline moiety. In the crystal, the cations are linked by pairwise N—H...O hydrogen bonds, forming inversion dimers enclosing an R 2 2(8) ring motif. The Cl− anion is linked to the cation by an N—H...Cl hydrogen bond. These units are linked by a series of C—H...O, C—H...N and C—H...Cl hydrogen bonds, forming layers lying parallel to the ab plane.

General Synthesis of 3‐Azabicyclo[3.1.1]heptanes and Evaluation of Their Properties as Saturated Isosteres**

“…We calculated the values of r , d , and ϕ of 3‐azabicyclo[3.1.1]heptanes from the X‐ray data of compounds 3 a HCl, 11 a HCl, and 15 a HCl. The related parameters for the representative bioactive pyridine 50 were calculated from the X‐ray data published in the literature [18] …”

“…The related parameters for the representative bioactive pyridine 50 were calculated from the X-ray data published in the literature. [18] The distance r in 3-azabicyclo[3.1.1]heptanes was ca. 0.3 Å shorter than that in the pyridine ring: 2.12 Å vs 2.41 Å (pyridine).…”

Unexpected Discovery of Saturated Pyridine Mimetics

“…The related parameters for the representative bioactive pyridine 46 were calculated from the Xray data published in the literature. 15 The distance r in 3-azabicyclo[3.1.1]heptanes was ca. 0.3 Å shorter than that in the pyridine ring: 2.12 Å vs 2.41 Å (pyridine).…”