4-Azatricyclo[5.2.2.02,6]undecane-3,5,8-triones as Potential Pharmacological Agents

A series of twenty six arylpiperazine and aminoalkanol derivatives of 4-azatricyclo[ 5.2.2.02,6]undecane-3,5,8-trione have been prepared. The synthesized compounds were evaluated for their cytotoxicity and anti-HIV-1 activity in MT-4 cells

Myrtenal and Myrtanal as Auxiliaries in the Synthesis of Some C,P-Stereogenic Hydroxyphosphine Oxides and Hydroxyphosphine-Boranes Possessing up to Four Contiguous Centers of Chirality

1,4- and 1,2-additons of secondary phosphine oxides to (1R)-myrtenal and (1S)-myrtanal were evaluated as potential routes to P,C-stereogenic phosphine oxides bearing additional hydroxyl or aldehyde functions. 1,4-Additions of racemic secondary phosphine oxides to (1R)-myrtenal were found to offer moderate to good stereoselectivity which shows some promise for utility in kinetic resolution processes, especially at lower conversions. In case of 1,2-additions making the process doubly asymmetric by using an enantiomerically pure secondary phosphine oxide as substrate turned out to be practical. The stereochemical course of the addition reactions under study is presented. The P-resolved 1,2-addition products were demonstrated to undergo facile reduction by BH3 at room temperature leading to the formation of the corresponding α-hydroxyphosphine-boranes with clean inversion of configuration at the P-centre. All P,C-stereogenic phosphine oxides and boranes that were isolated in the form of a single diastereoisomer were assigned their absolute configurations by means of X-ray crystallography and/or 2D NMR spectral techniques

4-Azatricyclo[5.2.2.02,6]undecane-3,5,8-triones as Potential Pharmacological Agents

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Resolution of P-Sterogenic 1-Phenylphosphin-2-en-4-one 1-Oxide into Two Enantiomers by (<i>R</i>,<i>R</i>)-TADDOL and Conformational Diversity of the Phosphinenone Ring and TADDOL in the Crystal State

The resolution of racemic 1-phenylphosphin-2-en-4-one 1-oxide (2), was achieved through the fractional crystallization of its diastereomeric complexes with (4R,5R)-(−)-2,2-dimethyl -α,α,α′,α′-tetraphenyl-dioxolan-4,5-dimethanol (R,R-TADDOL) followed by the liberation of the individual enantiomers of 2 by flash chromatography on silica gel columns. The resolution process furnished the two enantiomers of 2 of 99.1 and 99.9% e.e. at isolated yields of 62 and 59% (counted for the single enantiomer), respectively. The absolute configurations of the two enantiomers were established by means of X-ray crystallography of their diastereomerically pure complexes, i.e., (R)-2•R,R)-TADDOL and (S)-2•(R,R)-TADDOL. The structural analysis revealed that in the (R)-2•(R,R)-TADDOL complex, the P-phenyl substituent occupied a pseudoequatorial position, whereas in (S)-2•(R,R)-TADDOL, it appeared in both the pseudoequatorial and the pseudoaxial positions in four symmetrically independent molecules. Concurrent conformational changes of the TADDOL molecules were best described by the observed changes of a pseudo-torsional CO...OC angle that could be considered as a possible measure of TADDOL conformation in its receptor–ligand complexes. The structural analysis of the (R,R)-TADDOL molecule revealed that efficiency of this compound for use as an effective resolving factor comes from its ability to flexibly fit its structure to both enantiomers of a ligand molecule, producing a rare case of resolution for both pure enantiomers with one chiral separating agent. The resolved (R)-2 was used to assign the absolute configuration of a recently described (−)-1-phenylphosphin-2-en-4-one 1-sulfide by chemical correlation. In addition, an attempted stereoretentive reduction of (R)-2 by PhSiH3 at 60 °C revealed an unexpectedly low barrier for P-inversion in 1-phenylphosphin-2-en-4-one

Thiourea derivatives of 4-azatricyclo[5.2.2.02,6]undec-8-ene-3,5-dione - Synthesis and biological activity

A series of halogeno derivatives of thiourea bearing a polycyclic imide core has been efficiently synthesized and evaluated for antimicrobial activity. The structures of the compounds were established by 1H and 13C NMR and MS methods. The molecular structure of 4Clc was determined by an X-ray crystallography. Compounds containing 3-chloro-4-fluorophenyl substituent (3Cl4Fb, 3Cl4Fd) were found to be the most promising against Gram-positive bacteria (MIC values ranged from 8 to 32 μg/mL for standard and 32-64 μg/mL for hospital strains). The in vitro cytotoxicity against MT-4 cells of all compounds was evaluated

The Synthesis and Absolute Configuration of Enantiomeric Pure (R)- and (S)-3-(piperidin-3-yl)-1H-Indole Derivatives

This article describes the synthesis of new chiral 3-(piperidin-3-yl)-1H-indole derivatives (R)-10a-c and (S)-11a-c from the corresponding diastereomers: (3R, 2R) and (3S, 2R)-2-[3-(1H-indol-3-yl)-1-piperidyl]-2-phenyl-acetamides (3R, 2R)-4a, (3R, 2R)-6b, (3R, 2R)-8c and (3S, 2R)-5a, (3S, 2R)-7b, (3S, 2R)-9c. Diastereomers were obtained by N-alkylation of derivatives of racemic 3-(piperidin-3-yl)-1H-indoles 1a-c using (S)-2-(4-toluenesulfonyloxy)-phenylacetic amide (S)–II. The same method was applied to obtain (3R, 2S)-methyl-2-[3-(1H-indole-3-yl)-1-piperidyl]-2-phenylacetate (3R, 2S)-2a and (3S, 2S)-methyl-2-[3-(1H-indole-3-yl)-1-piperidyl]-2-phenylacetate (3S, 2S)-3a diastereomers by treating amine 1a with (R)-2-(4-toluenesulfonyloxy)-phenylacetic acid methylester (R)-I. Systematic studies via single crystal X-ray crystallography were used to determine the molecular structure of the racemates 1a-c and the absolute configuration of the enantiomers. The solid racemates 1b and 1c were “true racemates” crystallizing in a centrosymmetric space group, while 1a formed a racemic conglomerate of homoenantiomeric crystals. The absolute configuration was determined for the enantiomeric pairs (R)-10a/(S)-11a, (R)-10b/(S)-11b, and (R)-12c/(S)-13c, as well as for (3S,2S)-3a. Spectra of 1H, 13CNMR, HPLC, and HRMS for diastereomers and enantiomers were consistent with the determined structures

Synthesis and Biological Activities of Ethyl 2-(2-pyridylacetate) Derivatives Containing Thiourea, 1,2,4-triazole, Thiadiazole and Oxadiazole Moieties

Thirty six novel heterocyclic derivatives of ethyl 2-(2-pyridylacetate) were efficiently synthesized. The new compounds involve the linkage of a 2-pyridyl ring with thiosemicarbazide (compounds 1–7), 1,2,4-triazole (compounds 1a–7a), 1,3,4-thiadiazole (compounds 1b–7b), and 1,3,4-oxadiazole (compounds 1f–7f) moieties. The last group of compounds 1e–7e involves the connection of a 2-pyridyl ring with 1,2,4-triazole and thiourea. 1H-NMR, 13C-NMR and MS methods were used to confirm the structures of the obtained derivatives. The molecular structures of 3, 3b, 7a and 7f were further confirmed by X-ray crystallography. All obtained compounds were tested in vitro against a number of microorganisms, including Gram-positive cocci, Gram-negative rods and Candida albicans. In addition, the obtained compounds were tested for cytotoxicity and antiviral activity against HIV-1

Reduction of Functionalized Tertiary Phosphine Oxides with BH₃

A direct stereoselective conversion of tertiary hydroxyalkylphosphine oxides to the corresponding tertiary hydroxyalkylphosphine–boranes involving facile reduction of the PO bond by BH₃ under mild conditions has been developed. The unprecedented facility of reduction of the strong PO bond by BH₃, a mild reducing agent, has been achieved through an intramolecular PO···B complexation directed by proximal α- or β-hydroxy groups present in the phosphine oxide structures. As established by two chemical correlations, the developed transformation of hydroxyalkylphosphine oxides into hydroxyalkylphosphine–boranes takes place with complete inversion of configuration at P