Synthesis of γ-benzyltert-butoxycarbonyl-L-alanyl-D-glutamate and its derivatives

A convenient method of obtaining Boc-L-Ala-D-iGln-OBzl and its amide analogs by condensing the N-hydroxysuccinimidyl ester of Boc-L-Ala with the -benzyl ester ofD-Glu in the presence of NaHCO₃, followed by amidation of the resulting Boc-L-Ala-D-Glu--OBzl, is proposed. The use of l-adamantylamine and octadecylamine as amino components has enabled the corresponding -adamantylamide and octadecylamide of the dipeptide to be obtained.Simferopol' State University, 4 Yaltinskaya ul., Simferopol', Crimea, Ukraine 333036. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 101–103, January–February, 1998.     

Synthesis and certain transformations of γ-nitrosoalcohols

The -nitrosoalcohols (II), (XII), and (IX), respectively, have been synthesized by acid-catalyzed hydrolysis of 2-alkoxyisoxazolidines (I), (Xa, b), (Xla, b), and 3-(dimethoxyamino)-3-trifluoromethylbutanol-1 (VIII). The nitrosoalcohol (II) readily rearranges into the oxime (III), and (XII) is converted into the diol (XIII) by oxidation with atmospheric O₂ and denitrosation. For (IX) and (XII) ring-chain tautomerism with formation of 2-hydroxyisoxazolidines could not be detected by PMR spectroscopy.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1563–1568, July, 1991.     

Synthesis and Structure of Tetraphenylantimony γ-Alkylacetylacetonates

Tetraphenylantimony -ethylacetylacetonate and -allylacetylacetonate were synthesized by reacting pentaphenylantimony with -ethylacetylacetone or -allylacetylacetone in toluene. Their structures were determined by X-ray diffraction analysis. The coordination polyhedron of the antimony atom is a distorted octahedron. In the tetraphenylantimony -ethylacetylacetonate, the Sb–C bond lengths vary in the 2.156(2)–2.170(1) Å range, the SbOC(1)C(2)C(1")O" heterocycle is symmetric, and the Sb–O and O–C distances are 2.201(1) and 1.284(2) Å, respectively. In the tetraphenylantimony -allylacetylacetonate, the Sb–C bond lengths vary in the 2.159(1)–2.167(1) Å range and the Sb–O(1,2) distances are 2.234(1) and 2.191(1) Å.     

Study on Synthesis and Electrochemical Properties of Nanophase Li-Mo-spinel

Li-Mn-spinel was synthesized using the rheological phase recation method,First,the precursor was prepared by rheological phase reaction.The it was decomposed to form Li-Mn-spine,which was characterized by X-ray diffraction analysis and IR spectra.The particle size of Li-Mn-spinel was determined by the method of the transmission electron microscopy.The synthesized materials are of nanometer size with 30-100nm in the average diameter.The electrochemical properties of the Li-Mn-spinel were also studied.It proved that this method not only provided a simple practicable and effective route for the synthesis of Li-Mn-spinel,but also had many advantages such as lower sintering temperature,shorter sintering time,fine particles and particularly excellent electrochemical performances.     

Synthesis of γ-mercuridinitrohydrocarbons

Summary The denitration of -mercurinitro compounds has been studied and the corresponding organomercury dinitro derivatives have been obtained.     

Facile and Efficient Synthesis of γ-Lactone and Butenolide Derivatives

An efficient Baeyer–Villiger rearrangement of cyclobutanone derivatives was investigated. One-pot synthesis of keto-δ-lactone from the Baeyer–Villiger rearrangement products was developed. Meanwhile, the synthetic useful γ-lactone and butenolide derivatives could be easily prepared.     

Synthesis and Anticonvulsant Activity of γ-Aminobutyric Acid Derivatives

y-Aminobutyricacidisregardedasoneofthemaj0rinhibit0ryneur0transmittersinthemammaliancentralnervoussystem."'UnderPhysiologicalconditi0ns,y-aminobutyricacidpo0riycrossestheb1ood-brainbarrier.SoitisnoteffectivebyoraladministTation.3'4ItisIikelythatan0n-toxicderivativeofy-arninobutyricacidwhichentersthebraineasilywi1lhaveusefultheraPeuticproperties.Withthisinmind,wehavedesignedandsynthesizedl6derivativesofy-aminobubocacidwithaniminelinktoa1ip0philiccarrierinordert0facilitatethepassage0fy-aminobu…     

Synthesis and Antitumor Activity Evaluation of γ-Monofluorinated and γ,γ-Difluorinated Goniothalamin Analogues

A series of novel γ,γ‐difluorinated Goniothalamin analogues 4a – 4i and 6a – 6i were synthesized. The key steps included the construction of C‐5 stereocenter adjacent to gem‐difluoromethylene group by way of lipase AK catalyzed kinetic resolution, the introduction of aryl group via Stille coupling, and lactonization by 1,5‐oxidative cyclization. These γ,γ‐difluorinated Goniothalamin analogues 4a – 4i and their enantiomers 6a – 6i , together with several corresponding γ‐monofluorinated Goniothalamin analogues were biologically evaluated against four different cancer cell lines. Compound 7h showed a nearly equivalent potency as the parent (R)‐Goniothalamin in the micromolar range. The different fluorine effects between fluoromethylene and gem‐difluoromethylene on antitumor activity were discussed through the analysis of bioassay data.     

Divergent Synthesis of γ-Amino Acid and γ-Lactam Derivatives from meso-Glutaric Anhydrides

The first divergent synthesis of both γ-amino acid and γ-lactam derivatives from meso-glutaric anhydrides is described. The organocatalytic desymmetrisation with TMSN₃ relies on controlled generation of a nucleophilic ammonium azide species mediated by a polystyrene-bound base to promote efficient silylazidation. After Curtius rearrangement of the acyl azide intermediate to access the corresponding isocyanate, hydrolysis/alcoholysis provided uniformly high yields of γ-amino acids and their N-protected counterparts. The same intermediates were shown to undergo an unprecedented decarboxylation–cyclisation cascade in situ to provide synthetically useful yields of γ-lactam derivatives without using any further activating agents. Mechanistic insights invoke the intermediacy of an unconventional γ-N-carboxyanhydride (γ-NCA) in the latter process. Among the examples prepared using this transformation are 8 APIs/molecules of considerable medicinal interest.     

Chemical Modification of γ-Al2O3 Surface with Aryl Silanes

The effect of main factors (the nature and functionality of a modifier, the presence of water) on the chemical modification of -Al₂O₃ surface with aryl silanes was studied by an FTIR spectroscopy and elemental analysis.     

The Electrochemical Activity Determination of γ-Glutamyl Transpeptidase

Abstract

The electrochemical activity determination of γ-glutamyl-transpeptidase is described using the electrogenic L-γ-glutamyl paraaminodiphenylamide substrate. In order to correlate the results with classical measurements involving chromogenic substrates, linear calibration curves for the amperometric detection of the released free amine, the kinetics of the catalysis and the enzyme level in one plasma sample have been compared to photometric experiments effectuated in parallel runs, in the same conditions, with L-y-glutamyl paranitroanilide as the substrate. Results show that this new technique applies successfully to such evaluations.     

Synthesis of γ-keto alcohols and dihydrofurans from 2-furanpropanols

Summary A method was developed for the preparation of-keto alcohols and hence 2,3-dihydrofurans by the catalytic hydrogenation of 2-furanpropanols over platinized charcoal at 220° with formation of acetic esters of-keto alcohols, from which as a result of methanolysis-keto alcohols and dialkyldihydrofurans are formed.     

Synthesis and Mesomorphic Properties of Novel γ-Substituted β-Diketonates

The synthesis and mesomorphic properties of two series of novel γ-substituted β-diketonates have been reported. All of the compounds 2,4-dioxo-3-pentyl 4-[[4-(n-alkoxyl) cinnamoyl]oxy]cinnamatetes Ia-If (n=7-12) exhibit two monotropic phases(N and Sc) and have a wider mesophase range than the compounds 2,4-dioxo-3-pentyl 4-[[4-(n-alkoxyl) benzoyl]oxy] cinnamatetes Ⅱa-Ⅱf (n=7-12), which display one monotropic nematic phase (n=7-10) or an enantiotropic nematic phase for n=11 or two enantiotropic phases (N and Sc)for n=12.     

Synthesis of γ-sulfonyl δ-lactones and β-sulfonyl styrenes

A facile route to the synthesis of γ-sulfonyl lactones 5 and β-sulfonyl styrenes 6 has been developed, achieving moderate to good yields via the (1) NaH mediated Michael addition of β-ketosulfones 3 and methyl acrylate in refluxing THF and (2) NaBH₄ mediated stereoselective reduction/lactonization of δ-ketoesters 4 in boiling MeOH, or (3) boron trifluoride etherate mediated ring-opening of lactones 5 in MeOH at reflux.     

Synthesis and Characterization of New γ-Substituted Pentamethine Cyanine Dyes

Three novel pentamethine cyanine dyes with 3,5-dimethylpyridinium-1-yl and 4-benzylpyridinium-1-yl substituents in γ position of the methine chain were synthesized via a three-step procedure. The visible spectral behavior of these pentamethine cyanine dyes was examined in DMSO. Elemental analysis, IR, ¹H-NMR, ¹³C-NMR, and Mass spectral data confirmed the molecular structure of the newly synthesized compounds.     

A Simple Synthesis of γ-Cyclohomocitral

A simple and efficient synthesis for γ-cyclohomocitral (10), a key and versatile intermediate for the synthesis of some furanosesquiterpenes, is described. The formal total synthesis of (±) Pallenscensone (2) was accomplished.