Stereoselective Synthesis of (Z)-1-Benzhydryl-4-cinnamylpiperazines via the Wittig Reaction

Synthesis, molecular docking studies, and in vitro antimicrobial evaluation of piperazine and triazolo-pyrazine derivatives

For this work, two series of new piperazine derivatives (3a-o) and triazolo-pyrazine derivatives (3p-t) were synthesized in a single-step reaction. All twenty adducts were obtained in good to high yields and fully characterized by ¹H NMR, ¹³C NMR, IR, and mass spectrometry techniques. To further confirm the chemical identity of the adducts, a crystal of N-{[(4-chlorophenyl)-3-(trifluoromethyl)]-5,6-dihydro-[1,2,4]triazolo[4,3-a]}pyrazine-7(8H)-carboxamide (3t) was prepared and analyzed using X-ray crystallography. In vitro screening of the antimicrobial activity of all compounds (3a-t) was evaluated against five bacterial and two fungal strains. This study disclosed that N-{[(3-chlorophenyl)]-4-(dibenzo[b,f][1,4]thiazepin-11-yl)}piperazine-1-carboxamide (3o) was the superior antimicrobial with good growth inhibition against A. baumannii. Furthermore, the results from the performed molecular docking studies were promising, since the observed data could be used to develop more potent antimicrobials.

1-[Bis(4-fluoro-phen-yl)meth-yl]-4-[(2Z)-3-phenyl-prop-2-en-1-yl]piperazine-1,4-diium dichloride hemihydrate

The asymmetric unit of the title monohydrated salt, 2C₂₆H₂₈F₂N₂²⁺·4Cl^−.H₂O, consists of a 1-[bis­(4-fluoro­phen­yl)meth­yl]-4-[(2Z)-3-phenyl­prop-2-en-1-yl]piperazine-1,4-diium cation with a diprotonated piperizine ring in close proximity to two chloride anions and a single water mol­ecule that lies on a twofold rotation axis. In the cation, the piperazine ring adopts a slightly distorted chair conformation. The dihedral angles between the phenyl ring and the 4-fluoro­phenyl rings are 89.3 (9) and 35.0 (5)°. The two fluoro­phenyl rings are inclined at 65.0 (5)° to one another. In the crystal, N—H⋯Cl hydrogen bonds and weak C—H⋯Cl inter­molecular inter­actions link the mol­ecules into chains along [010]. In addition, weak C—H⋯O inter­actions between the piperizine and prop-2-en-1-yl groups with the water mol­ecule, along with weak C—H⋯Cl inter­actions between the prop-2en-1-yl and methyl groups with the chloride ions, weak C—H⋯F inter­actions between the two fluoro­phenyl groups and weak O—H⋯Cl inter­actions between the water mol­ecule and chloride ions form a three-dimensional supra­molecular network.

(Z)-1-Di-phenyl-methyl-4-(3-phenyl-prop-2-en-yl)piperazine

In the title compound, C26H28N2, the piperazine group adopts a chair conformation with the exocyclic N-C bonds in equatorial orientations. The dihedral angle between the geminal benzene rings is 80.46 (12)° and the C=C-C-N torsion angle is 145.9 (2)°. In the crystal, weak C-H⋯π inter-actions link the mol-ecules into [100] chains.