A. A. Bogolyubov

New Synthetic Thrombin Inhibitors: Molecular Design and Experimental Verification

Background The development of new anticoagulants is an important goal for the improvement of thromboses treatments. Objectives The design, synthesis and experimental testing of new safe and effective small molecule direct thrombin inhibitors for intravenous administration. Methods Computer-aided molecular design of new thrombin inhibitors was performed using our original docking program SOL, which is based on the genetic algorithm of global energy minimization in the framework of a Merck Molecular Force Field. This program takes into account the effects of solvent. The designed molecules with the best scoring functions (calculated binding energies) were synthesized and their thrombin inhibitory activity evaluated experimentally in vitro using a chromogenic substrate in a buffer system and using a thrombin generation test in isolated plasma and in vivo using the newly developed model of hemodilution-induced hypercoagulation in rats. The acute toxicities of the most promising new thrombin inhibitors were evaluated in mice, and their stabilities in aqueous solutions were measured. Results New compounds that are both effective direct thrombin inhibitors (the best KI was <1 nM) and strong anticoagulants in plasma (an IC50 in the thrombin generation assay of approximately 100 nM) were discovered. These compounds contain one of the following new residues as the basic fragment: isothiuronium, 4-aminopyridinium, or 2-aminothiazolinium. LD50 values for the best new inhibitors ranged from 166.7 to >1111.1 mg/kg. A plasma-substituting solution supplemented with one of the new inhibitors prevented hypercoagulation in the rat model of hemodilution-induced hypercoagulation. Activities of the best new inhibitors in physiological saline (1 µM solutions) were stable after sterilization by autoclaving, and the inhibitors remained stable at long-term storage over more than 1.5 years at room temperature and at 4°C. Conclusions The high efficacy, stability and low acute toxicity reveal that the inhibitors that were developed may be promising for potential medical applications.

Reactions of Amidines with 5-Methylene-1,3-dioxolan-2-ones

The composition and yields of the products from the reaction of 4,4-dialkyl-5-methylene-1,3-dioxolan-2-ones with amidines depend on the structure of the initial amidine and on the reaction conditions. 2-Aminopyridines lead to 3-substituted 4-hydroxy-4-methyloxazolidin-2-ones and 4-methylene-oxazolidin-2-ones and also to sym-carbamides. 2-Amino-4,6-dimethylpyrimidine leads to the corresponding 4-methyleneoxazolidin-2-one. 3-Aminothiazoles give linear oxourethanes and sym-carbamides.

Reaction of 4-Methylene-1,3-dioxolan-2-ones with Hydrazines

The structure of the products of the reaction of 4-methylene-1,3-dioxolan-2-ones with hydrazines is a function of the structure of the starting hydrazine. 1,3,4-Oxadiazin-2-one derivatives are obtained from hydrazine hydrate. 3-Arylaminooxazolidin-2-ones are obtained from monoarylhydrazines, while mixtures of these derivatives are obtained from aliphatic monoalkylhydrazines.

The use of 4-(bromomethylene)-5,5-dimethyl-1,3-dioxolan-2-one as masked α-bromo-α'-hydroxy ketone in the synthesis of heterocyclic systems

Abstract4-(Bromomethylene)-5,5-dimethyl-1,3-dioxolan-2-one was obtained on the basis of the readily obtainable 4-methylene-5,5-dimethyl-1,3-dioxolan-2-one. It forms 2-imidazo[1,2-a]pyridin-2-yl-2-propanol with 2-aminopyridine, 11a-hydroxy-1,1-dimethyl-3-oxo-1,5,11,11a-tetrahydro[1,3]oxazolo[3,4-a]pyrido[1,2-d]-10-pyrazinium bromide with 2-(aminomethyl)pyridine, and the corresponding derivative of 4-hydroxyoxazolidin-2-one with 2-(3,4-dimethoxyphenyl)ethylamine. The last product was converted by intramolecular amidoalkylation without isolation into 10b-(bromomethyl)-8,9-dimethoxy-1,1-dimethyl-1,5,6,10b-tetrahydro[1,3]oxazolo[3,4-a]isoquinolin-3-one.

Reactions of 5-methylene-1,3-dioxolan-2-ones with amines. Synthesis of 2-oxazolidinones

The reaction of 5-methylene-1,3-dioxolan-2-ones with aromatic or aliphatic amines as well as with the sodium salts of amino acids leads to 4-hydroxy-2-oxazolidinones. The reaction conditions depend on the basicity of the amines. The use of o-phenylenediamine in this reaction leads to the formation of a new heterocyclic system.

Dehydration of 4-hydroxy-4-methyl- 3-phenylamino-oxazolidin-2-ones

The dehydration of two 5,5-disubstituted 4-hydroxy-4-methyl-3-phenylaminooxazolidin-2-ones into the corresponding 4-methylene-3-phenylaminooxazolidin-2-ones has been carried out. The structure of the products was confirmed by X-ray diffraction analysis.

1-oxa-3-azapentalen-2-ones as precursors of cis-2-amino alcohols: Synthesis from propargyl alcohols, CO2, and amines using an intramolecular amidoalkylation reaction of oxazolidin-2-ones

The reaction of 5-methyl-5-(4-methyl-3-pentenyl)-4-methylene-1,3-dioxolan-2-one with primary amines gives the corresponding 4-hydroxy-4-methyloxazolidin-2-ones. These undergo an intramolecular amidoalkylation reaction to form 1-oxa-3-azapentalen-2-ones which are potential precursors of cyclopentanyl cis-2-amino alcohols.