Synthesis and Moessbauer Spectra of Four-Coordinated Tin Compounds Containing Tin-Copper Bonds

IntroductionAlthoughmanypapershavereportedinvestigationsonthesynthesesandstruLturesofcomplexeswithtin-transitionmetalbonds""',fewpapersdealwithcomplexeswithtin-copperbonds.Inthepresentpaper,sevenorganotincompoundscontainingSn-Cubonds,namely[Ph2P(CH2).PPh2](CuSnPPh3)2(n-4)and(Ph2PR)CuSnPh3(R=Ph,Bu,Am),havebeensynthesized.Thetin-ll9MoessbauerspectraofthesecompoundshavebeendeterminedinordertostudythecharateristicsofSn-Cubondsandthesymmetryofthecomplexes.PreparationAllreactionswerecarri…     

Synthesis and Molecular Recognition of Novel Cyclic Pseudopeptides Containing L-Glutamic Acid or L-Aspartic Acid Backbones

Novel cyclic pseudopeptides containing L-glutamic acid or L-aspartic acid backbone structures were efficiently synthesized and characterized. Their chiral recognition properties for L- and D-amino acid methyl ester hydrochloride were discussed also.     

Synthesis of Some New 1,3,2-Oxazaphosphinine, 1,3,2-Diazaphosphinine,Acyclic, and/or Cyclic α-Aminophosphonate Derivatives Containing the Chromone Moiety

The synthesis of some new 1,3,2-oxazaphosphinine 18, 1,3,2-diazaphosphinine 19, acyclic, and cyclic α-aminophosphonate derivatives 3–17 containing the chromone moiety have been achieved via reaction of 3-(phenyliminomethyl)chromone (1), 3-(phenylaminomethylene)-2-hydroxychromanone (4), and/or 3-(phenylamino-methylene)-2-(phenylamino)chromanone (5) with diethyl phosphite, tris(2-chloroethyl)phosphite, and phenylphosphonic dichloride. Structures of the products were verified on the basis of their elemental analyses, IR, ¹H, and ³¹P NMR spectral data.     

Synthesis of Bis(macrocyclic) Polyamines Containing Rigid Bridging Groups

Thesgnthesi8ofbis(macrocyclic)POlyamineligandsandtheirdinuclearcomplexesoftransitionmetalionshaveattractedmuchinterestinrecentyears.Andava-rietyofsyStemshavebeenreported[1-s1.Theprotonatedfreeligandshavebeenusedashostsforanionicsubstrates.Theresultingdinuc1earcomplexeshavebeenstudiedasmodelsfortheactivesitesofphosphateases.Ofspecialinterestisthehydrolysisofactivatedphosphatemonoester[3J.Here,weconfineourreporttothesrothe8isofthreenew8ymmetricalbis(1,4,7-triazacyclononane)ligandsNa-ccontaini…     

Geländer Molecules with Orthogonal Joints: Synthesis of Macrocyclic Dimers

Orthogonal joints, understood as connections with an angle of 90°, were introduced in the design of the “Geländer” model compounds 1 and 2 . The banister, consisting of a conjugated carbazole dimer linked by either 1,3-butadiyne ( 2 ) or a single thiophene ( 1 ), wraps around an axis composed of a phthalimide dimer due to the dimensional mismatch of both subunits, which are interconnected by phenylene rungs. The “Geländer” structure was assembled from a monomer comprising the 1,4-diaminobenzene rung with one amino substituent as part of a 4-bromo phthalimide subunit forming the orthogonal junction to the axis, and the other as part of a masked 2-ethynyl carbazole as orthogonal joint to the banister. The macrocycle was obtained by two sequential homocoupling steps. A first dimerization by a reductive homocoupling assembled the axis, while an oxidative acetylene coupling served as ring-closing reaction. The formed butadiyne was further derivatized to a thiophene, rendering all carbons of the model compound sp² hybridized. Both helical structures were fully characterized and chirally resolved. Assignment of the enantiomers was achieved by simulation of chiroptical properties and enantiopure synthesis.     

Synthesis and Spectra of Bichromophore Compounds Containing Oxazole or Oxadiazole Ring

Fifteen of the bichromophore compounds containing oxazole or oxidation ring have been synthesized. Their structures have been identified by IR, 1H NMR spectra and elemental analysis. The UV spectra, fluorescence spectra and the laser conversion efficiencies have been determined . The results of determination show that the absorption and emission spectra Pf the bichromophore compounds are different from those of the corresponding single chromophore compounds.     

Synthesis and Stereochemistry of New Cyclic Phosphate-phosphonates

1,3,2alloxaphoSPhorinanederivahveshavbeengenetallypwibythcPhoSI)horylatiowith(thio)PhOSPhorylchlorideinliteraturd'].bor,studiesonthepeeSsandstemeheInistIyofl,3,2choxaphoSPhorinane2-suffidcs(selenideStythetriS(diethyndno~nem~weretwmprted.Furthermore,a-hydroxyphoSPhonatedCriVativarebiologitallyaodvd2]andhavboshowntoinhibittheempmesrenin,EPSPtwse,andHIVProtcascI'1.DuetothebiQlOgitalandStereochendcalintereSt,wedCsi~andrynthchndthenoVelcyClicpbOSPhate-PhoSI)bonateS7a4tyaoneWprocedu…     

Synthesis and Crystal Structure of Unprecedented Pentanuclear Cu_5~Ⅱ Complex Containing both Macrocyclic and Azido Ligands

The organic-inorganic hybrid complex with formula [(CuL)2Cu3(μ-1,1-N3)4(ClO4)2],complex 1,{CuL,[5,6:14,15-dibenzo-1,4,8,12-tetraazacyclopentadeca-7,13-diene-2,3-dione(2-)]copper(II)},has been synthesized and structurally determined. The crystals of complex 1 crystallize in the triclinic system with space group P1,a=0.92983(12) nm,b=1.09644(14) nm,c=1.27396(16) nm,α=70.782(2)°,β=86.266(2)°,γ=78.284(2)°. In this com-plex,the five copper ions are bridged by macrocyclic oxamide groups and azido. Furthermore,C―H...     

Design and Synthesis of Muramyl Dipeptide Cyclic Analogue

A new conformationalloy restricted cyclic analogue of muramyl dipeptide was designed and manually synthesized by our “Meshed-Bag Gathered-Bunch” method with a combination of Fmoc,ally and N-1-(4,4-dimethyl-2,6-dioxocyclo-hexylidene) ethyl chemical protection strategy.     

Use of Silicon Substituents in the Syntheses of Natural and Non-natural Molecules

Trimethylsilyl groups have been used in our research as a director as well as a bulky and lipophilic group in our quest for natural and non-natural molecules.     

Synthesis and Properties of Polyetherketones Containing Sulfide and Phthalazinone

High molecular weight copoly(ether ketone)s (PEK) based on 4-(4-hydroxyphenyl)-1-phthalazinone (DHPZ)/4,4′-thiobisphenol (TBP)/4,4′-diflourodiphenylketone (DFK) were prepared by nucleophilic substitution polycondensation. The copolymers were characterized by FT- and ^1H-NMR. Thermal properties and solubility of copolymers were studied.     

The Synthesis and Structures of Cyclic Oligoether-Esters. 4. The Formation and Conformation of Macrocyclic Ether Rings of α, β-Dioxo-cyclopolyoxa Oligo(Ether-Esters)

The cyclic ether-ester formation from the condensation of oxalyl chloride with tri and tetraethyleneglycols were tried in benzene/dioxan solutions in the presence of pyridine. The conformation of the ether linkage of the isolated products were investigated by high resolution ¹³C, ¹H and 2D-COSY spectra.     

A Short and Highly Stereoselective Synthesis of Cerebrosterol

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Switchable Synthesis of 7- and 14-Membered Cyclic Peptides Containing N-Methyl- and β-Amino Acids Utilizing Microflow Technology

Smaller cyclic peptides containing non-proteinogenic amino acids have garnered much attention for use as drugs, but their chemical synthesis is extremely challenging. In this study, a rapid (60.5 min) synthesis of 7- and 14-membered cyclic peptides containing N-methyl- and β-amino acids was achieved by only switching the concentrations (0.20 M or 0.01 M) of the substrates. The developed approach required neither expensive transition-metals nor expensive coupling agents. As far as we could ascertain, this is the first report of the synthesis of smaller (≤16-membered) cyclic N-methylated peptides via dimerization-cyclization strategy.     

Synthesis and Spectral Properties of Macrocyclic Compounds Containing 1,3,4‐Thiadiazole Moeties Connected by a Carbon–Oxygen Bridge

The syntheses of 1∶1‐macrocycles 3 (n=1), unsymmetrical macrocycle 5 (m=0, n=1), 2∶2‐macrocycle 5 (m=n=1 and 2), 3∶3 macrocycle 7, and several open‐chain ethereal compounds prepared from 2,5‐dichloro‐1,3,4‐thiadiazole 1 and various polyethylene glycols dianions are described. Structural proofs are afforded by their mass and NMR spectral features. The quaternization studies of a few macrocycles with methyl iodide at elevated temperature furnished a diketo derivative 8 through a facile Hilbert–Johnson reaction.     

Synthesis of Novel Dendrimers Containing Amino Acids and Peptides

Dendrimers are known for their well-defined, regular, highly branched architectures with a large number of functional groups1. Recently, dendrimers have been widely researched in different fields, such as molecular light havesting, catalysts, liquid cryst…     

Improved and Highly Versatile Synthesis of 5‐Aryltropones

Abstract

The use of 5‐iodo‐2‐methoxytropone in palladium(0)‐catalyzed coupling reactions with a variety of arylboronic acids has resulted in significantly improved reaction yields and times for a sterically and electronically diverse series of novel 5‐aryltropones. In addition, the required 5‐iodo‐2‐methoxytropone was conveniently synthesized in excellent yield.     

Synthesis,Structures, and Complexation with Phenolic Guests of Acridone-Incorporated Arylene–Ethynylene Macrocyclic Compounds

Acridone units were incorporated into the arylene–ethynylene structure as polar arene units. Cyclic trimers consisting of three acridone-2,7-diyl units and three 1,3-phenylene units were synthesized by Sonogashira couplings via stepwise or direct route. X-ray analysis revealed that the trimer had a nearly planar macrocyclic framework with a cavity surrounded by three carbonyl groups. In contrast, the corresponding tetramer had a nonplanar macrocyclic framework. ¹H NMR measurements showed that the trimer formed a 1 : 1 complex as a macrocyclic host with dihydric phenol guests, and the association constants were determined to be ca. 1.0×10³ L mol⁻¹ for hydroquinone or resorcinol guests in CDCl₃ at 298 K. The calculated structures of these complexes by the DFT method supported the presence of two sets of OH⋅⋅⋅O=C hydrogen bonds between the host and guest molecules. The spectroscopic data of the cyclic trimers and tetramers are compared with those of reference acridone compounds.     

Synthesis of Obyanamide, a Marine Cytotoxic Cyclic Depsipeptide

Obyanamide 1 is a cyclic depsipeptide that was recently isolated from the marine cyanobacterium Lyngbya confervoides by Moore and co-workers1. This compound displayed a potent inhibitory effect on both KB and LoVo cells in vitro. Several structural analog…