A. B. Dobrynin

Synthesis and antituberculosis activity of novel unfolded and macrocyclic derivatives of ent-kaurane steviol.

New derivatives of steviol 1, the aglycone of the glycosides of Stevia rebaudiana, including a novel class of semisynthetic diterpenoids, namely macrocyclic ent-kauranes were synthesized. These compounds possess antituberculosis activity inhibiting the in vitro growth of Mycobacterium Tuberculosis (H37R(V) strain) with MIC 5-20 μg/ml that is close to MIC 1 μg/ml demonstrated by antituberculosis drug isoniazid in control experiment. For the first time it was found that the change of ent-kaurane geometry (as in steviol 1) of tetracyclic diterpenoid skeleton to ent-beyerane one (as in isosteviol 2) influences on antituberculosis activity.

2-chloro-3,3,5-trimethyl-2,3-dihydro-1,2λ5-oxaphosphole 2-oxide as precursor in a new synthesis of dialkyl(diaryl)-(2-methyl-4-oxopent-2-yl)phosphine oxides

A new approach has been developed to the synthesis of dialkyl(diaryl)(2-methyl-4-oxopent-2-yl)-phosphine oxides that are structural analogs of the drug dimephosphon. This approach is based on the reaction of 2-chloro-3,3,5-trimethyl-3H-1,2λ5-oxaphosphole 2-oxide with Grignard compounds, and it ensures high yields of the target products. The structure of bis(2-methoxyphenyl)(2-methyl-4-oxopent-2-yl)phosphine oxide was determined by X-ray analysis. (2-Methyl-4-oxopent-2-yl)dipropylphosphine oxide with magnesium bromide formed a 4: 1 complex whose structure was also determined by X-ray analysis.

Hybrid compounds of ent-beyerane diterpenoid isosteviol with pyridinecarboxylic acid hydrazides. Synthesis, structure, and antitubercular activity

Hybrid compounds derived from natural diterpenoid isosteviol and antitubercular drug isoniazid (isonicotinic acid hydrazide) and its isomers (nicotinic and 2-picolinic acid hydrazides) were synthesized, and their structure in crystal and in solution was studied. The newly synthesized compounds were found to inhibit Micobacterium tuberculosis (H37RV strain) in vitro, the minimal inhibitory concentration being 10–20 μg/ml.

1-chloroacetyloxindole(isatin) in reactions with some N-nucleophiles. Unexpetedly easy cleavage of chloroacetyl group

Reactions of 1-chloroacetyloxindole and 1-chloroacetylisatin with some secondary amines, Girard’s reagent T and thiourea were studied. All investigated reactions proceeded via cleavage of the acyl group to form 3-substituted isatin or oxindole derivatives.

Stereoselective Synthesis and Interconversions of 1,9-Diaza-3,7,11,15-Tetraphosphacyclohexadecanes

We report here the novel stereoselective method of design of macrocyclic tetraphosphines, based on the principles of covalent self-assembly.

Polyelectrolyte micro- and nanocapsules with varied shell permeability controlling the rate of esters hydrolysis

Two variants of layer-by-layer deposition of polyelectrolytes (polyacrylic acid and polyethyleneimine) for the encapsulation of low-molecular-weight hydrophobic substrates (carboxylic acid esters) were proposed. The spectrophotometric method was used to study the kinetics of alkaline hydrolysis of the esters by monitoring the permeability of microcapsule shells. The first procedure provides a preliminary microencapsulation of substrates into the carbonate matrix to form stable capsules 7–10 μm in size with a low wall permeability. According to the second procedure, the polyelectrolytes were adsorbed directly on the dispersed substrate. In this case, nanosized capsules are formed, whose permeability is controlled by the ultrasonic treatment and the number of deposited layers.

New N-Mannich bases obtained from isatin and piperazine derivatives: the synthesis and evaluation of antimicrobial activity

A Mannich reaction of isatin with monosubstituted piperazines in the presence of aqueous formaldehyde was used to synthesize new, as well as two previously described derivatives of 1-piperazinomethylisatins, which were further converted to isoindigo derivatives. The antimicrobial activity of the obtained heterocycles was evaluated.

Effect of the substituent on the phosphorus atom on the reaction of aminophosphines with 1-alkylisatins

Depending on the substituent on the phosphorus(III) atom, reactions of tris(dialkylamino)phosphines, 2-diethylamino-1,3,2-benzodioxaphosphole, and benzene-1,4-diylbis(N,N,N′,N′-tetraethylphosphonous diamide) with 1-alkylisatins lead to the formation of isoindigo derivatives, spirophosphoranes, or spirooxiranes whose structure was determined by NMR spectroscopy and X-ray analysis.

New triamidophosphonium acetals and their condensation with resorcinol and its derivatives

A number of new acetals bearing phosphonium moieties with P-N bonds were prepared. Their condensation with resorcinols in acidic water-alcohol solutions was studied, which led to new phosphonium salts having a diarylmethane fragment.

Synthesis and Comparative Analysis of the Steric and Supramolecular Structures of Diastereomers of 4,4-Bis(trifluoromethyl)-2-(fluoroalkoxy)-6,7-benzo-1,3,2λ5- dioxaphosphepin-5-one 2-Oxides

Reaction with hexafluoroacetone of 2-fluoroalkoxy-5,6-benzo-1,3,2-dioxophosphorinan-5-ones containing a chiral fluorinated exocyclic substituent on the phosphorus atom, with hexafluoroacetone leads to formation of 4,4-bis(trifluoromethyl)-6,7-benzo-1,4,2-dioxaphosphepines with a high regio- and stereoselectivity. The configuration of all isolated individual diastereomers was established by X-ray diffraction. The molecular and supramolecular structure of the compounds were examined in terms of the proposed model that takes account of the revealed effect of separation of hydrophilic and lipophilic regions in the crystal.