Synthesis and hydrazinolysis of β-(1,3,4-oxadiazol-2-yl)pyridines

Cyclization of the hydrazide of 5-ethoxycarbonyl-2,6-dimethylpyridine-3-carboxylic acid by acylation with aromatic or aliphatic acid chlorides with subsequent boiling in POCl₃ or heating in orthoformic acid gave the corresponding ethyl 2,6-dimethyl-5-(5-R-1,3,4-oxadiazol-2-yl)pyridine-3-carboxylate. The cyclization of the reaction products with hydrazine hydrate has been studied. Cyclization of the dihydrazide of 2,6-dimethyl-3,5-pyridinedicarboxylic acid under analogous conditions gave only 3,5-bis-(5-R-1,3,4-oxadiazol-2-yl)-2,6-dimethylpyridines, containing R = 2-FC₆H₄, H.     

Reaction of β-iminoalcohols with sulfur dioxide. Synthesis of (±)-(2-hydroxyalkylamino)phenyl(isopropyl)-methanesulfonic acids

Reactions of 2-(N-isopropylidene)amino-2-methylpropanol, 2-(N-benzylidene)-, and 2-(N-isopropylidene) aminoethanols with sulfur dioxide in aqueous ethanol medium produce (±)-(2-hydroxyalkylamino)-phenyl(isopropyl)methanesulfonic acids. Structure of (±)-(2-hydroxyethylamino)phenylmethanesulfonic acid was determined by X-ray diffraction method.     

Synthesis of α-trifluoromethyl-phenethylamines from α-trifluoromethyl β-aryl enamines and β-chloro-β-(trifluoromethyl)styrenes

A novel synthetic approach towards α-trifluoromethyl-phenethylamines was elaborated by reduction of the electron deficient β-aryl-α-trifluoromethyl enamines and imines with sodium cyanoborohydride in the presence of trifluoroacetic acid. The starting imines were prepared by the reaction of primary amines with β-aryl-α-trifluoromethyl enamines or β-chloro-β-(trifluoromethyl)styrenes.     

Synthesis and Crystal Structure of Diethyl (4,6-diamino-1,3,5-triazine-2-yl) phosphonate

1　INTRODUCTIONSomeoforganophosphoruscompounds,includingmanyheterocycliccompoundscontainingphosphonogroup,havegoodbioactivityinorganism[1].Duetotheirrela-tionwithbiochemical/biological,pharmacologicalandpesticidalresearch,hetero-cycliccompoundscontainingphosphonogrouphavebeensynthesizedbysomeofnewsyntheticmethods,inwhichseveralnewbuildingblockwereused,suchasβ-phos-phonicenemines,[2,3]isocyanomethylphosphonate,[4]β-functionalγ-oxo-alkylphos-phonates,[5]andacetylenicphosphonate.[6]Inourpr…     

Synthesis and crystal structure of β-N-(5-methyl-4-oxo-5,6-dihydro-4H-1,3-thiazin-2-yl)isonicotinohydrazide

In the presence of amines under mild conditions, β-N-(methacryloylcarbamoythioyl)isonicotinohydrazide underwent intramolecular heterocyclization to give β-N-(5-methyl-4-oxo-5,6-dihydro-4H-1,3-thiazin-2-yl)isonicotinohydrazide, the spatial structure was confirmed by X-ray crystallography.     

Synthesis of N-Aryl-N′- (5-aryloxymethyl-1,3,4-thiadiazol-2-yl) ureas under Microwave Irradiation

The rapid heating effect of microwave irradiation has caught the attention of synthetic chemists in the recent times due to the remarkable reduction of reaction time. It is an efficient method because of its virtue of rapid heating capability, high yield and simple procedure. The superiority of these virtues goes beyond of traditional heating reaction.     

Synthesis,Crystal Structure and Fluorescent Property of a Zn(Ⅱ) Complex with 1,3-Bis(imidazol-1-yl)benzene and 1,3-Benzenedicarboxylate

A novel zinc complex [Zn(BIB)(bdc)]n(1, BIB = 1,3-bis(imidazol-1-yl)benzene, bdc = 1,3-benzenedicarboxylate) has been synthesized in solvothermal conditions. The title complex was characterized by elemental analysis, IR spectra, thermal analysis, single-crystal and powder X-ray diffraction. The result proved that the alliance of BIB and aromatic carboxylic acids is good for the diversity of getatable structure. Complex 1 crystallizes in the monoclinic system of P2/c space group with a = 11.5591(10), b = 9.6239(8), c = 33.727(3) ?, β = 103.816(3)°, V = 3643.4(5) ?3, Z = 8, μ = 1.385 mm-1, F(000) = 1792, Dc = 1.603 g/cm3 and Mr = 439.72 g/mol. Additionally, luminescent properties of complex 1 are also investigated and it shows good fluorescence.     

Enantioselective synthesis of β-amino acids. Part 10: Preparation of novel α,α- and β,β-disubstituted β-amino acids from (S)-asparagine

Perhydropyrimidinone (S)-1 is alkylated with very high diastereoselectivity to give trans products (2S,5R)-3, (2S,5R)–4 and (2S,5R)-5. Dialkylation of (S)-1 also proceeds with complete stereoselectivity to afford adducts (2S,5R)-6, (2S,5S)-6, (2S,5R)-7 and (2S,5S)-7. Hydrolysis (6N HCl, 100°C) of monoalkylated derivative (2S,5R)-3 gives enantiopure α-substituted β-amino acid (R)-8. Hydrolysis of dialkylated adducts 6 and 7 affords enantiopure α,α-disubstituted β-amino acids (R)- or (S)-9 and (R)- or (S)-10. Related iminoester (2S,6S)-2 is alkylated with complete diastereoselectivity to give products (2S,6S)-11–13 whose hydrolysis under relatively mild conditions (2N CF₃CO₂H, CH₃OH, 100°C) affords enantiopure N-benzoylated β,β-disubstituted β-amino acid esters (S)-14–16, with intact double bonds in the olefinic substituents.     

Synthesis and crystal structure of nickel(Ⅱ) and zinc(Ⅱ) complexes with 2,4-bis(3,5-dimethylpyrazol-1-yl)-6-methoxyl-1,3,5-triazine

2,4-Bis(3,5-dimethylpyrazol-1-yl)-6-methoxyl-1,3,5-triazine(bpt) has been synthesized by using a new, simple and general method with high yields. Reactions of bpt with Ni(CIO4)2 · 6H2O and Zn(CIO4)2 · 6H2O in methanol gave mononuclear complex [Ni(bpt)2] · (CIO4)2 · H2O and ternary complex [Zn(mpt)2(dmp)](CIO4)2 respectively, where mpt (2,4-dimethoxy-6-(3,5-dimethyl-pyrazol-1-yl)-1,3,5-triazine) and dmp(3,5-dimethylpyrazole) are the alcoholysis products of bpt in the presence of Zn2+ ion. A possible mechanism for this catalytic reaction was proposed. X-ray crystal structure for ligand bpt, Ni and Zn complexes are reported. The protonated form of the ligand bpt crystallizes as its perchlorate salt including one molecule of water, [Hbpt · H2O · CIO4]. The proton is located on one pyrazole N-atom. [Hbpt ?H2O ?CIO4], in which [Hbpt]+ is in cis-cis conformation, are packed in slipped stacks of approximately parallel layers. The π-π overlap interactions between the non-protonized pyrazoles of the adjace     

The reaction of β-dicarbonyl compounds with trifluoromethylsulphenyl chloride. Part I. CF3S-substituted esters,anilides of β-keto acids,and their Schiff bases: Synthesis and stability.

The reactions of the β-keto acid derivatives with trifluoromethylsulphenyl chloride were carried out to give the α-SCF₃ substituted esters, anilides, and their Schiff bases of acetyl- and benzoylacetic acids. Ethyl esters of α-(trifluoromethylthio)acetoacetic and α-(trifluoromethylthio)benzoylacetic acids heated in dimethylsulphoxide/water solution give trifluoromethylthioacetone and ω-(trifluoromethylthio)acetophenone respectively, whereas with potassium hydroxide solution they form trifluoromethylthioacetic acid in a good yield.     

Stereoselective synthesis of novel N-(α-l-arabinofuranos-1-yl)-l-amino acids

In lead detoxification, the α-anomer of N-glycocyl-l-amino acid is more potent than its β-anomer. Here a six-step-reaction route for stereoselectively preparing N-(α-l-arabinose-1-yl)-l-amino acids is reported. Treating l-arabinose with acetic anhydride and sodium acetate provided 1,2,3,5-tetra-O-acetyl-l-arabinofuranose in 90% yield. After removing the 1-acetyl group, the thus formed 2,3,5-tri-O-acetyl-l-arabinofuranose and N-(2-nitrophenylsulfonyl)-l-amino acid t-butylesters were treated with triphenylphosphine to perform Mitsunobu dehydration and form 2,3,5-tri-O-acetyl-l-arabinofuranosyl-l-[N-(2-nitrophenylsulfonyl)]amino acid t-butylesters 2a–f, and the ratios of their α- to β-anomer ranged from 8/1 to 9/1. Chromatographic separation provided epimerically pure 2a–f-α and 2a–f-β. In the presence of CF₃CO₂H, 2a–f-α and 2a–f-β were converted to α- and β-anomers of N-(2,3,5-tri-O-acetyl-l-arabinofuranosyl)-N-(2-nitrobenzenesulfonyl)-l-amino acids, 3a–f-α and 3a–f-β, in 87–92% yields. While in the presence of NaOCH₃, 3a–f-α and 3a–f-β were converted to α- and β-anomers of N-(l-arabinofuranosyl)-N-(2-nitrobenzenesulfonyl)-l-amino acids, 4a–f-α and 4a–f-β, in 90–96% yields. Treating 4a–f-α and 4a–f-β with N-ethyldiisopropylamine (DIPEA) and thiophenol, their 2-nitrophenylsulfonyl groups were removed, and the α- and β-anomers of N-(l-arabinose-1-yl)-l-amino acids were formed in 70–79% yields. The bioassay confirmed that the lead detoxification activity of the α-anomer was significantly higher than that of the β-anomer.     

Synthesis and crystal structure of 2′-(3,5-dioxo-1,2,4-triazinane-1-yl)acetic acid and the product of its reaction with copper(II) chloride

A new organic compound, 2-(3,5-dioxo-1,2,4-triazinane-1-yl)acetic acid, was prepared by transit template synthesis, and its crystal structure was determined. The ability of this compound to form stable metal complexes, where it acts as an N,O-chelating ligand, was demonstrated using its Cu(II) compound as an example.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 3, 2005, pp. 187–194.Original Russian Text Copyright © 2005 by Filippova, Bologa, Simonov, Gdaniec, Gerbaleu.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis and structural studies of homooligomers of geminally disubstituted β(2,2)-amino acids with carbohydrate side chain

A new class of geminally disubstituted C-linked carbo-β(2,2)-amino acids (β(2,2)-Caa) were prepared from d-glucose. The structures of homooligomeric di-, tetra-, and hexapeptides prepared from (S)-β(2,2)-Caa were studied with NMR (in CDCl(3)), CD, and Molecular Dynamics calculations. These β(2,2)-peptides have shown the presence of stable 6-membered (6-mr) NH(i)···CO(i) intra-residue H-bonded (C(6)) strands. It was found that the strand structures realized in these systems were additionally stabilized by the electrostatic interaction arising due to the proximity of amide proton (NH(i)) to the oxygen of the preceding methoxy group (O(Me)(i-1)) at the C3 carbon of the carbohydrate ring. The new β(2,2)-Caa residues with additional support to H-bonding considerably expand the domain of foldamers.     

Indole derivatives. 138. Synthesis of α-(5-indolyl)ethylamine and 5-(2-aminoethoxy)- and 5-(aminoethylthio)tryptamines

The reaction of 5-acetylindole with hydroxylamine with subsequent reduction of the resulting oxime gave -(5-indolyl)ethylamine. Coupling of 4-(2-phthalimidoethoxy)- and 4-(2-phthalimidoethylthio)phenyldiazonium chlorides with ethyl -acetyl--phthalimidovalerate, subsequent cyclization of the resulting hydrazones, hydrolysis, decarboxylation, and removal of the phthalyl protecting group led to the formation of 5-(2-aminoethoxy)- and 5-(2-aminoethylthio)tryptamines, respectively.For Communication 137, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 46–48, January, 1992.     

Enantiodifferentiation of aminophosphonic and aminophosphinic acids with α- and β-cyclodextrins

Cyclodextrins were used as chiral selectors for the ³¹P NMR determination of the enantiomeric excess of aminoalkanephosphonic and aminoalkanephosphinic acids. Most of these acids form inclusion complexes with α- and/or β-cyclodextrin and upon increasing the cyclodextrin to aminophosphonic acid molar ratio ³¹P NMR signals for (R)- and (S)-enantiomers separate. ROESY spectra allowed the determination of structures of the inclusion complexes.     

Synthesis and magnetism of μ-1,3,5-benzenetricarboxylatocopper(II) trinuclear complexes

Summary Three new Cu^II trinuclear complexes, namely [Cu₃(BZT)(phen)₃(ClO₄)₃]·6H₂O (1), [Cu₃(BZT)(Nphen)₃ (ClO₄)₃]·6H₂O (2) and [Cu₃(BZT)(bipy)₃ (ClO₄)₃]·3H₂O (3) (BZT) = 1,3,5-benzenetricarboxylato, phen = 1,10-phenanthroline, Nphen = 5-nitro-1,10-phenanthroline, bipy = 2,2-bipyridyl, have been synthesized, with 1,3,5-benzenetricarboxylato as the bridged ligand, and characterized by elemental analysis, and i.r. and electronic reflection spectra. We propose that the complexes have an extended 1,3,5-benzenetricarboxylatobridged structure containing three Cu^II atoms. The variable-temperature magnetic susceptibilities of the complexes were measured in the 77–300 K range. The magnetic coupling parameters are consistent with an antiferromagnetic exchange model based on the Hamiltonian operator [=–2J( _{1 2}+ _{1 3}+ _{2 3}, where S ₁=S ₂=S ₃=1/2, giving the antiferromagnetic coupling parameters of 2J = – 18.6 cm^-1 for (1)–(3).     

Synthesis of β-amino alcohols by ring opening of epoxides with amines catalyzed by cyanuric chloride under mild and solvent-free conditions

Abstract

The 2,4,6-trichloro-1,3,5-triazine catalyzed synthesis of β-amino alcohols by aminolysis of epoxide under solvent-free condition is described. Mild reaction conditions, short reaction times, inexpensive and readily available catalysts, and excellent yields of the products with high regioselectivity are attractive features of this methodology.     

Amphiphilic conjugates of β-cyclodextrin with acetylsalicylic and 2-(4-isobutylphenyl)propionic acids

New amphiphilic β-cyclodextrin derivatives containing pharmacologically important aromatic and aliphatic monocarboxylic acid fragments at both primary and secondary hydroxy groups were synthesized with the use of palmitic, acetylsalicylic, and 2-(4-isobutylphenyl)propionic acid chlorides. The position of the acyl groups in the carbohydrate fragments of β-cyclodextrin was determined by ¹³C NMR spectroscopy.     

Synthesis of polysubstituted 1,3-cyclohexadienes from β-branched α,β-alkenals and monoesters of ylidenemalonic acids

3-Methyl- and 3-phenyl-2-butenal react with monoesters of alkylidene-, alkenylidene-, and arylmethylenemalonic acids in the presence of piperidine as the catalyst to give esters of 4,6-disubstituted 1,3-cyclohexadienecarboxylic acids in 23–96% yields. Under the same conditions cyclohexylideneacetic aldehyde reacts with the monoesters of prenylidene- and benzylidenemalonic acid to afford mixtures of 1,8a-trans- and 1,8a-cis-isomers of 1-substituted alkyl 1,5,6,7,8,8a-hexahydronaphthalene-2-carboxylates, the ratios and configurations of which were determined by means of¹H NMR spectroscopy. In some cases the formation of cyclic dienes is impeded by the competing process of decarboxylation of acidic ylidenemalonates. The derivatives of 4,6-diphenyl-1,3-cyclohexadienecarboxylic acid were shown to be convenient precursors for the preparation ofmeta-terphenyls.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. I, pp. 154–161, January, 1996.