Olga B. Bazanova

Synthesis and antituberculosis activity of the first macrocyclic glycoterpenoids comprising glucosamine and diterpenoid isosteviol

The first macrocyclic glycoterpenoids comprising glucosamine and diterpenoid isosteviol moieties were synthesized and evaluated for inhibition activity against Mycobacterium tuberculosis H37Rv.

Macrocyclic derivatives of steviolbioside, a glycoside isolated from Stevia Rebaudiana

Macrocycles consisting of two or four steviolbioside (S. Rebaudiana glycoside) fragments linked at the carboxy groups by an octamethylene chain and at the 16-positions by alkanedihydrazide spacer derived from adipic, suberic, or sebacic acid have been synthesized.

A novel acid-catalyzed rearrangement of 2-substituted-3-(2-nitrophenyl)oxiranes for the synthesis of di- and mono-oxalamides

A novel one-pot synthetic approach to N1-(2-carboxyaryl)-N2-(aryl or H)oxalamides from 3-(2-nitroaryl)oxirane-2-carboxamides via the classical Meinwald rearrangement and a new rearrangement sequence has been developed. The methodology is applicable to the synthesis of N-(2-carboxyphenyl)aryloxalmonoamides from (3-(2-nitrophenyl)oxiran-2-yl)(aryl)methanones. The method is operationally simple and high yielding, thus providing a new useful formula for both anthranilic acid derivatives and oxalamides.

Functionalization of the double bond in the glycoside of the Stevia rebaudiana plant steviolbioside, as a way to macrocyclic glycosides

The C16=C17 bond in the glycoside steviolbioside from the plant Stevia rebaudiana was oxidized for the first time. Ketone, thiosemicarbazone, and oxime of steviolbioside with a heptaacetylated sophorosyl fragment, as well as binuclear and tetranuclear macrocyclic derivatives of this rebaudioside were synthesized.

Lariat ethers in the chiral recognition of amino acid esters:electrospray ionization mass spectrometry investigation

The ability of the crown ethers (1–4), containing the ortho- or para- methoxyphenoxy-methyl substituents in their structure, to chiral recognition in reference to amino acid esters has been investigated by electrospray ionization mass spectrometry (ESI-MS). The method allows registering the diastereomeric complexes between the studied crowns as hosts and the protonated alanine, phenylglycine and phenylalanine methyl esters as guests in the gas phase. ESI-MS experiments using isotopically labeled guests provide robust and reproducible results, indicating a moderate degree of chiral discrimination in the series of the studied crown ethers. ESI-MS experiments using achiral amine as a reference yielded the results comparable with the previous method. It has been found that (S)-enantiomers of the crowns bind predominately (S)-enantiomers of the amino acid esters, and vice-versa. It has been shown that the chiral ortho-substituted crown (S)-1 demonstrates the more pronounced values for chiral discrimination as compared with the para-substituted crown (S)-2. This fact indicates the interrelationship between the chiral recognition and the lariat nature of crown 1. Increasing the size of the cavity and the presence of a flat aromatic moiety in crowns 3 and 4 strengthens their complexing ability, simultaneously weakening the enantioselectivity of the complexation.

Comparative analysis of interactions of some lariat crown ethers and their unsubstituted analogues with alkali metal salts in the gas phase by MALDI mass spectrometry

In this work, interactions of some crown ethers, including lariat ethers bearing a side-arm methoxyphenoxymethyl substituent, with alkali metal salts were studied by matrix assisted laser desorption/ionization mass spectrometry. Peaks of cationized molecules [M + Cat]+, sandwich complexes [2M + Cat]+, [3M + Cat]+ ions, and cluster ions [2M + 2Cat + An]+ and [2M + 3Cat + 2An]+ were observed in the mass spectra; herein M is a crown ether molecule, Cat is an alkali metal cation, and An is a monobasic acid anion. The results were compared with previously obtained data for 15-crown-5, [ortho]- and [para]-methoxyphenoxymethyl-15-crown-5 ether mixtures with sodium salts. The conclusions made before, that an increase in the shielding degree of the cation in complexes with lariat ethers led to a significant decrease in the peak intensity of cluster ions [2M + 2Cat + An]+, were confirmed. For potential lariat ethers the absence or only trace amounts of such cluster ions along with the presence of an intense cluster ion peak in the mass spectrum for an unsubstituted analogue can serve a test for the involvement of the lateral fragment of the crown ether in complex formation, i.e., the lariat effect.

Synthesis and structure of phosphorylated acetals

The Kabachnik-Fields reaction in a triple system (aminoacetal-paraform-diethyphosphite) resulted in the formation of the previously unknown aminophosphonates that contained the acetyl group and also their monoesters. Structures of the products were confirmed by 1H NMR, IR spectra and X-ray diffraction analysis. The MALDI mass spectra indicated that the presence of N-hydroxyethoxyphosphorylmethylaminomethyl groups underlies the ability of these compounds to self-assembly with the formation of n-dimensional H-bonded associations.

Chiral (2-cyanophenoxy)methyl-15-crown-5 in diastereomeric discrimination of amino acid esters according to the data of electrospray ionization mass spectrometry

The ability of [(2-cyanophenoxy)methyl]-15-crown-5 lariat ether enantiomers to diastereomeric discrimination with respect to hydrochlorides of 1-phenylethylamine and methyl esters of alanine, phenylalanine, and phenylglycine was studied by electrospray ionization mass spectrometry. The mentioned crown ether is available in non-racemic form owing to the procedure of preferential crystallization of enantiomers of its precursor. The quantitative estimation of the differences in the formation of diastereomeric complexes between the crown ether and the guests was performed by two independent methods: application of the guests with isotopic markers and using an additive of achiral amine-displacer. Both approaches indicate the existence of a moderate chiral discrimination: The (S)-enantiomer of the crown ether binds prevailingly the (S)-enantiomer of the guest, and vice versa.

Transformations of anilides of 3-aryl-2,3-epoxypropionic acids when exposed to acidic agents

Anilides of 3-aryl-2,3-epoxypropionic acids on treatment with aqueous HBr gave 3-aryl-3-bromo-2-hydroxypropionic acid anilides and (in some cases) 2-bromo-3-hydroxy regioisomers. Cyclization of these products into 3-arylquinolin-2(1H)-ones was studied.

Chiral lariat ethers based on spontaneously resolved 3-(2-cyanophenoxy)propane-1,2-diol

Lariat ethers are macrocyclic polyethers (crown ethers) containing one ore more side arms with electron-donating groups [1]. Such substituents may enhance the selectivity and efficiency of binding guest molecules or ions (lariat effect) [2, 3]. We previously demonstrated lariat effect in the complexation of oand p-methoxyphenoxymethyl-15-crowns-5 with alkali metal salts in the crystalline and gas phases [3]. It was found that only the o-methoxyphenoxymethyl substituent ensures efficient binding of sodium cation.