Synthesis and anti-histaminic evaluation of N-phenyl-(alkyl)-5-(dialkylamino)methyl-2-amino-2-oxazolines

New N-phenyl(alkyl)-5-(dialkylamino)methyl-2-amino-2-oxazolines, 5a-e, have been synthesized from the corresponding 3-phenyl(alkyl)carbamoyl-2-iminooxazolidines 2. A two-stage hydrolysis reaction led finally to the corresponding ring-opened N-phenyl(alkyl)-N'-[1-(3-(dialkylamino)-propan-2-ol)]ureas 4. The oxazoline ring was regenerated through an intramolecular nucleophilic substitution involving an halogen atom introduced by the reaction of thionyl chloride on 4. Pharmacological properties of 5a-e were evaluated on histaminic and adrenergic receptors in guinea-pig trachea and rat aorta. Compounds 5b and 5e showed a selective anti-histaminic effect on guinea-pig airways, but a significant response was obtained for a concentration >10(-6) M. No pharmacological activity was obtained with oxazoline 5c whereas oxazolines 5a and 5d seemed to present a non-selective effect on the contractile mechanism of the smooth muscle cell.

Determination of pKa values of 2-amino-2-oxazolines by capillary electrophoresis

The dissociation constants of new 2-amino-2-oxazolines were determined by capillary electrophoresis (CE) as a new technique. A method based on a linear model has been used in the CE determination. A series of eight 2-amino-2-oxazolines are investigated to determine their ionization constant. Among them, three new oxazolines synthesized are presented. The Ka values were obtained from the plots of reciprocal effective mobility against inverse concentrations of protons. The potentiometric method (PM) was performed as a comparative method. No significant differences were observed between the determined dissociation constants using both methods. Thus, the pKa values have been found to vary between 8.55 and 8.68.

Synthesis and pharmacological evaluation of 5-dialkylaminomethyl-2-amino-2-oxazolines as H1-antagonists

New 5-dialkylaminomethyl-2-amino-2-oxazolines have been synthezised in two steps from the corresponding dialkylamines. They were evaluated in-vitro as H1-antagonists. Compounds 1c, 1d and 1j significantly antagonized histamine-induced contraction of guinea-pig trachea with a rightward shift of the concentration-response curve to histamine. Compound 1f, 5-[(4-benzyl-1-piperidinyl)methyl]-2-amino-2-oxazoline, induced an increase in acetylcholine Emax (the maximal response to acetylcholine 10(-3) M) and a shift to the left of the concentration-response curve. The lack of effect of this compound on histamine-induced contraction rules out a non-selective potentiation of the contraction mechanisms. Preliminary structure-activity results were reported partly based on physicochemical results.

Physicochemical and crystallographic evidence for polymorphism of the racemic ethyl (2-chloromethyl-2,3-dihydro-5H-oxazolo [3, 2-a]pyrimidin-5-one)-6-carboxylate

The various crystalline forms of an original bicyclic compound [ethyl (2-chloromethyl-2,3-dihydro-5H-oxazolo[3, 2-a]pyrimidin-5-one)-6-carboxylate); EOC] have been obtained and characterized by powder and single-crystal X-ray diffraction, differential scanning calorimetry (DSC), and infrared (IR) and Raman spectroscopy. At 4 degrees C in methanol, a monoclinic racemate (form II) crystallized from the racemic mixture, whereas at 20 degrees C, an orthorhombic racemate (form I) was isolated in trichloroethylene. By increasing the temperature, a solid-solid transition from the stable form II to the stable form I was observed with a Guinier-Simon camera. A I --> II transformation was observed at ambient temperature by DSC.

2-Amino-2-oxazolines, Part 9: Synthesis and pharmacological evaluation of N-phenyl-N'-[1-[3-(1-aryl-4-piperazinyl)propan-2-ol]]ureas

N-Phenyl-N'-[1-[3-(1-aryl-4-piperazinyl)propan-2-ol]]ureas (3) were synthesized from the 3-phenylcarbamoyl-5-[(1-aryl-4-piperazinyl)methyl]-2-iminooxazolidine s (1) via the corresponding 2-oxazolidinones (2). The prepared compounds were screened for their antiallergic and analgesic activities.

2-amino-2-oxazolines, VII: Influence of structural parameters on the antidepressant activity of 5-(1-aryl-4-piperazino)methyl-2-amino-2-oxazolines

A series of 5-(1-aryl-4-piperazino)methyl-2-amino-2-oxazolines has been prepared and screened for antidepressant activity. Their lipophilic behaviour has been discussed in relation to the nature and the position of substituents on the aromatic ring. The influence of steric effects on the pharmacological activity has been investigated using experimental methods (X-ray diffraction, NMR) and theoretical calculations (semi-empirical quantum mechanics). The ortho-substitution on the phenyl ring or the C-alpha substitution on the piperazine ring by a methyl group results in the same effects i.e. an increase of the angle between the two rings up to 64 degrees (X-ray and calculation) and a loss of the antidepressant activity. Using NMR, only the influence of the ortho-substitution has been observed.

2-Aminooxazolines, I: Crystal and molecular structure of 5-(1-aryl-4-piperazino)methyl-substituted derivatives with antidepressant activity

The structure of two 5-(1-aryl-4-piperazino)methyl-2-aminooxazolines were determined by X-ray crystallography. An amino form is preponderant in a free base whereas an imino form is preponderant in a salt. The molecular conformations were studied by molecular mechanics.