Synthesis of mono- and di-α-l-fucosylated 2-acetamido-2-deoxy-N-glycyl-β-d-glucopyranosylamines,spacered fragments of glycans of N-glycoproteins

Russian Chemical Bulletin - α-l-Fucp-(1→3)-d-GlcNAc, α-l-Fucp-(1→6)-[α-l-Fucp-(1→3)]-d-GlcNAc, and β-d-Galp-(1→3)-[α-l-Fucp-(1→4)]-d-GlcNAc...     

Studies on carbohydrates. Part 33: Synthesis of spacer-armed 2-acetamido-2-deoxy-4-O-β-d-galactopyranosyl-α-d-mannosides and their dimers

The mixture of 3,6-di-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-2-azido-2-deoxy-d-glucopyranosyl 1-acetates or 1-trichloroacetates and the corresponding mannose type glycosyl donors reacted with the spacer arms di- and triethylene glycol, in dichloromethane solution with BF₃·OEt₂ and TMSOTf as promotors at room temperature to give highly selective products. Only the mannose type products were obtained.     

Synthesis of ( )-5α-Hydroxy-β-selinene and (-)-5β-Hydroxy-β-selinene

Eudesmanederivativeshavebeendrawingconsiderableattentionduetotheirwidespectrumofbiologicalproperties,particularlyantifeedant,cellgroWthinhibitoryandplantgroWthregulatingactivitiesl'2.Recently,twoepimericeudesmanederivatives( )-5a-hydroxy-6-selinene1and(-)-56-hydroxy-6-selinene2wereisolated3fromtheaerialpartsofCSubtraPicaFMell.,andtheirstructuresweredeterminedbyspectroscopicmethods.Herein,wereportafacilesynthesisofbothtwodiastereomers1and2from( )-dihydrocarvone3infivesteps,usingtheregioselect…     

Synthesis of some mono- and bis-spiro-β-lactams of benzylisatin

Some new mono- and bis-spiro-β-lactams of benzylisatin were prepared by Staudinger’s ketene-imine [2+2] cycloaddition reaction. The cycloadducts were characterized by spectral data including ¹H NMR, ¹³C NMR, IR and mass spectra. The configuration of benzylisatin and one of mono-spiro-β-lactams (5a) was established by X-ray crystal analysis.     

Synthesis of a (β-acetamido-α-acetoxyethyl)boronic ester via azido boronic esters

(Azidomethyl)boronic esters of 1,2-dicyclohexyl-1,2-ethanediol (“DICHED”) and pinanediol have been prepared from the corresponding (bromomethyl)boronic esters. Conversion to (2-azido-1-chloro- or bromoethyl)boronic esters by reaction with a (dihalomethyl)lithium followed. Attempted displacement of halide from DICHED (2-azido-1-haloethyl)boronates with alkoxides failed. Reaction of either pinanediol or DICHED (2-azido-1-chloromethyl)boronate with sodium acetate in acetic acid yielded the 1-acetoxy derivative as a ∼1:1 mixture of diastereomers, indicating probable involvement of an α-boryl carbocation intermediate. Hydrogenation of the pinanediol azido boronic ester over platinum in a solution of hydrogen chloride in dioxane was accompanied by deacetylation to form the impure (2-amino-1-hydroxyethyl)boronic ester hydrochloride. Attempted purification of this material resulted in deboronation to ethanolamine. Acetylation yielded pinanediol (2-acetamido-1-acetoxyethyl)boronate.     

Convenient synthesis of mono- and di-β-hydroxy-β-bis(trifluoromethyl)-(di)imines from β-hydroxy-β-bis(trifluoromethyl)-ketones and (di)amines

A series of novel β-hydroxy-β-bis(trifluoromethyl)-imines (2a-j) and di(β-hydroxy-β-bis(trifluoromethyl))-diimines (3a-f) were prepared in moderate to good yields via a simple two-step approach: first, β-hydroxy-β-bis(trifluoromethyl)-ketones (1a-c) were obtained by a catalyst-free aldol reaction between liquid hexafluoroacetone sesquihydrate and ketones (acetone, acetophenone, and pinacolone, respectively); then, condensation of the latter fluorinated β-ketols 1a-c with primary amines or diamines was achieved in the presence of Lewis (montmorillonite, InBr₃, La(OTf)₃) or Brönsted (PTSA) acid catalysts. The molecular structures of mono- and di-β-hydroxy-β-bis(trifluoromethyl)-(di)imines 2e,h and 3a,f were determined and found to exhibit strong intramolecular (R)N?H-O hydrogen bonding.     

Stereoselective Synthesis and Crystal Structure Analysis of N-Naphthy1-2-deoxy-α-d-ribopyranosylamine

A new compound N-naphthy1-2-deoxy-α-D-ribopyranosylamine was synthesized and structurally determined.It crystallizes in the orthorhombic system,space group P212121 with a =8.361(2),b=12.432(3),C=12.791(4)A,Z=4,V=1329.6(6)A3,DC=1.295 g/cm3,F(000)= 552,C15H17NO3 and Mr=259.30.All the active hydrogen atoms arc involved in the formation of hydrogen bonds in the molecule.     

Synthesis and physicochemical properties of 1-(2-alkylamidoethyl)-2-alkyl-2-imidazolines based on α,α′-branched carboxylic acids

Condensation of diethylenetriamine with lauric, 2-ethylhexanoic, and α,α′-branched C_10,12-carboxylic acids results in 1-(2-alkylamidoethyl)-2-alkyl-2-imidazolines. A stability of the synthesized compounds relative to the acid and alkaline hydrolysis was studied. Their protonation constants were determined. The effect of the structure of the alkyl substituents on the distribution of the substance between the organic and aqueous phases was examined. The principal possibility of extracting Zn(II), Fe(III), Cu(II), Co(II), Mn(II) chlorides from hydrochloric acid solutions was shown. A mixture of 1-(2-alkylamidoethyl)-2-alkyl-2-imidazolines based on the α,α′-branched carboxylic acids was suggested as a potential extractant of the metal salts from hydrochloric acid and chloride solutions.     

Stereoselective Synthesis and Crystal Structure Analysis of N-Naphthyl-2-deoxy-α-D-ribopyranosylamine

A new compound N-naphthyl-2-deoxy-α-D-ribopyranosylamine was synthesized and structurally determined. It crystallizes in the orthorhombic system, space group P212121 with a = 8.361（2）, b = 12.432（3）, c = 12.791（4） A^°, Z= 4, V= 1329.6（6） A^°^3, Dc= 1.295 g/cm^3, F（000） = 552, Cl5H17NO3 and Mr= 259.30. All the active hydrogen atoms are involved in the formation of hydrogen bonds in the molecule.     

Synthesis of di-μ-oxo-tetra-(α-pentyloxy)tin(Ⅳ)phthalocynine

Axially substituted tin phthalocyanines, namely dichloride-tetra-(pentyloxy) tin (IV) phthalocyanine 3 and its dimmer di-cyanine 4 were synthesized. The catalytic effect of H2O-free CaCl2 in quinoline was used for condensation of dihydroxy tin phthalocyanine 3 to the cofacially array dimmer 4. Their structures were characterized by UV-vis, IR, elemental analysis, MS, as well as 1HNMR spectroscopy.     

Synthesis of N-(N-bromoacetylglycyl)-β-D-glycopyranosylamines,derivatives of monoand di-α-L-fucosylated diand trisaccharides

Russian Chemical Bulletin - N-(N-Bromoacetylglycyl)-β-glycopyranosylamines of diand trisaccharides, namely, α-LFucp-(1→6)-β-D-GlcNAcp-NHCOCH2NHCOCH2Br,...     

Synthesis and structures of spiro-σ-complexes based on 2-(2-benzylaminophenyl)-5,6-dimethylbenzimidazole

The reactions of 2-(2-benzylaminophenyl)-5,6-dimethylbenzimidazole with electrophilic 8-chloro-5,7-dinitroquinoline and 7-chloro-4,6-dinitrobenzofuroxan afforded two new bipolar spiro--complexes. The structure of the complex prepared by the latter reaction was established by X-ray diffraction analysis. The activation parameters of the stereodynamic rearrangement of quinoline spirane were determined by dynamic NMR spectroscopy.Results of the study were presented at the International Conference Modern Trends in Organoelement and Polymer Chemistry dedicated to the 50th anniversary of the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences (May 30–June 4, 2004, Moscow).Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1990–1994, September, 2004.     

Synthesis and properties of ω-(hydroxyaryl)alkylsulfides based on 2-isobornyl-6-methyl-4-propylphenol

Proceeding from 2-isobornyl-6-methyl-4-propylphenol new derivatives have been synthesized having sulfur atoms included in different functional groups. Antiradical and antioxidant activity, as well as membrane-protecting properties of the derivatives of 2-isobornyl-6-methyl-4-propylphenol in chemical and biological model systems have been investigated.     

Studies on the Thioglycosides of N-Acetylneuraminic Acid 7: Synthesis of S-(α-Sialyl)-(2↠6)-β-D-Hexopyranosyl and -(2↠6)-β-D-Lactosyl Ceramides and their Biological Activity

ABSTRACT

The coupling of the sodium salt of methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3, 5-dideoxy-2-thio-D-glycero-α-D-galacto-2-nonulopyranosonate (17) with 2-(trimethylsilyl)ethyl 2,3,4-tri-O-acetyl-6-bromo-6-deoxy-β-D-galactopyranoside (5), glucopyranoside (10), and 2-(trimethylsilyl)ethyl 2,3,6,2′,3′,4′-hexa-O-acetyl-6′-bromo-6′-deoxy-β-D-lactoside (16), gave the corresponding α-thioglycosides 18, 21, and 24 of the 2-thio-N-acetyl-neuraminic acid derivative in good yields, which were converted, via selective removal of the 2-(trimethylsilyl)ethyl group, trichloroacetimidation, and coupling with (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (27), into the ß-glycosides 28, 32, and 36, respectively.

Compounds 28, 32, and 36 were transformed, via selective reduction of the azide group, coupling with octadecanoic acid, O-deacetylation, and de-esterification, into the title compounds 31, 35, and 39, which showed potent inhibitory effect for sialidases from influenza and other viruses.     

Synthesis of optically active macrolides bearing di- and triethylene glycol and dicarboxylic acid hydrazide moieties from (-)-α-pinene

Russian Chemical Bulletin - Six optically active macroheterocycles bearing ester and dihydrazide moieties were synthesized from available natural (-)-α-pinene through the intermediate keto...     

Synthesis of O-α-L-Fucopyranosyl-(1→2)-O-β-D-galactopyranosyl-(1→4)-2-acetamido-2-deoxy-D-glucopyranose. The H-Blood Group Specific Trisaccharide

Abstract

Different reaction conditions were investigated for the preparation of benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranoside (5). Compound 5 on reaction with 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide afforded the 4-O-substituted 2-acetamido-2-deoxy-β-D-glucopyranosyl derivative which, on O-deacetylation, gave benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-4-O-β-D-galactopyranosyl-β-D-glucopyranoside (8). The trimethylsilyl (Me₃Si) derivative of 8, on treatment with pyridineacetic anhydride-acetic acid for 2 days, gave the disaccharide derivative having an O-acetyl group selectively introduced at the primary position and Me₃Si groups at the secondary positions. The latter groups were readily cleaved by treatment with aqueous acetic acid in methanol to afford benzyl 2-acetamido-4-O-(6-O-acetyl-β-D-galactopyranosyl)-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranoside, which on isopropylidenation gave the desired, key intermediate benzyl 2-acetamido-4-O-(6-O-acetyl-3,4-O-isopropylidene-β-D-galactopyranosyl)-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranoside (12). Reaction of 12 with 2,3,4-tri-O-benzyl-α-L-fucopyranosyl bromide under catalysis by bromide ion afforded the trisaccharlde derivative from which the title trisaccharide was obtained by systematic removal of the protective groups. The structures of the final trisaccharide and of various intermediates were established by ¹H and ¹³C NMR spectroscopy.     

Synthesis and light-emitting properties of 2-(N-phenyl-α-naphthylamino) and 2-dimesitylboron-7-(N-phenyl-α-naphthylamino)-9,9-diethylfluorene

A fluorescent organic triarylamine with a symmetric structure, 2,7-bis(N-α-naphthyl-phenylamino)-9,9- diethylfluorene (NPAEF) was synthesized using two methods, modified Ullmann coupling and modified palladium-catalyzed amination. An activated copper and a combination of Pd(OAc)2/P(t-Bu)3 and Pd(dba)2/P(t-Bu)3 were selected as catalysts to improve yields of reactions. These synthetic procedures were also successfully applied to an asymmetric 2-dimesitylboron-7-(N-phenyl-α-naphthylamino)-9,9-diethylfluorene ...     

Synthesis and Crystal Structure of α,α,β,β-5,10,15,20-Tetrakis(2-aminophenyl)porphyrin

The title compound, α,α,β,β-5,10,15,20-tetrakis(2-aminophenyl)porphyrin, has been obtained and characterized by single-crystal X-ray diffraction.The crystal belongs to the monoclinic system, space group C2/c with a = 31.804(6), b = 19.314(4), c = 12.872(3) -, β = 90.592(3)°, Z = 4, V = 7907(3) -3, Dc = 1.193 g/cm3, Mr = 1419.67, λ(MoKα) = 0.71073 -, μ = 0.073 mm-1, F(000) = 2984, R = 0.0773 and wR = 0.2045.The crystallographic analysis indicates the existence of N-H…( intermolecular interactions and hydrogen bonds which link the complex molecules into a 3D network structure.