Tetraazamacrocyclic Nickel(II) Complexes Containing a Pendant Amino Group

Reduction of the nitro group in 5-nitromethyl-1,4,8,11-tetraazacyclotetradeca-11-enenickel(II) complexes 1 leads to 5-aminomethyl-substituted macrocyclic nickel(II) complexes. Orange, protonated “arm off” (3 and 5) and violet “arm on” (2 and 4) complexes were isolated and characterized. Relative configurations of substituents and conformations of the macrocyclic ligands are proposed on the basis of NMR evidence. The isolation of free ligands is also described.     

聚己内酯大分子单体接枝丙烯酰胺共聚物的合成与表征

首次制备了末端为双键的功能化聚己内酯(PCL)大分子单体(AECL);AECL与丙烯酰胺(AM)在过硫酸钾引发剂作用下进行水溶液自由基聚合反应,合成了接枝PCL侧链的水溶性新型聚丙烯酰胺共聚物(PAM-g-PCL),其结构经1H NMR,IR和元素分析表征.PAM-g-PCL的特性粘数为3.4 dL·g-1～5.3 dL·g1-.     

Aggregation and Polymerization of Amphiphilic Macromonomers with a Double Bond at the Hydrophilic Terminal

Macromonomers with general formula C(n)[EO](m)-CO-CH=CH(2) were synthesized by endcapping corresponding Brij compounds with acryloyl chloride. Their aggregation behavior evaluated against the parent Brij compounds, the saturated and triblock analogs advocate that the terminal double bond is protected by the partially looped PEG chain. The homo- and copolymerization behavior in aqueous media is consistent with this possibility. Copyright 2000 Academic Press.     

Synthesis and Structure Analysis of a Tripeptide Containing N-methyl Group Amino Acid

A convenient method of synthesizing a tripeptide-containing N-methyl group amino acid was developed using O-benzotriazole-N,N,N',N'-tetramethyluronium-hexafluorophosphate as the condensing agent. The crystals of tripeptide had white needles belonging to the orthorhombic space group P2_12_12_1. The conformational preference for homochiral tripeptides with one N-methylated amide bond was also investigated. Crystal-structure analysis showed that homochiral tripeptides with an internal N-methylated amide bond preferred a trans-amide form, thereby giving the peptide β-fold characteristics. Intermolecular C–H···O and N–H···O hydrogen bonds linked the molecules into a one-dimensional chain and stabilized the structure.     

末端含香兰醛亚胺Schiff碱的1,3,5-三嗪核-聚酰胺树枝状化合物的合成

2,4,6-三氯-1,3,5-三嗪与亚胺基二(乙酸乙酯)进行亲核取代反应制得1,3,5-三嗪核-六酯基树枝状化合物(1);1经乙二胺酰胺化制得1,3,5-三嗪核-六乙二胺基树枝状化合物(2);2与丙烯酸甲酯进行Michael加成反应制得1,3,5-三嗪核-六胺基-十二酯基树枝状化合物(3);3再经乙二胺酰胺化制得1,3,5-三嗪核-六胺基-十二胺基树枝状化合物(4);4与香兰醛在乙醇中反应合成了末端含香兰醛亚胺Schiff碱的1,3,5-三嗪核-聚酰胺树枝状化合物,其结构经NMR和IR表征.     

Dipolar Dyes with a Pyrrolo[2,3‐b]quinoxaline Skeleton Containing a Cyano Group and a Bridged Tertiary Amino Group: Synthesis,Solvatofluorochromism, and Bioimaging

Two strongly polarized dipolar chromophores possessing a cyclic tertiary amino group at one terminus of the molecule and a CN group at the opposite terminus were designed and synthesized. Their rigid skeleton contains the rarely studied pyrrolo[2,3‐b]quinoxaline ring system. The photophysical properties of these regioisomeric dyes were different owing to differing π conjugation between the CN group and the electron‐donor moiety. These dipolar molecules showed very intense emission, strong solvatofluorochromism, and sufficient two‐photon brightness for bioimaging. One of these regioisomeric dyes, namely, 11‐carbonitrile‐2,3,4,5,6,7‐hexahydro‐1H‐3a,8,13,13b‐tetraazabenzo[b]cyclohepta[1,2,3‐jk]fluorene, was successfully utilized in two‐photon imaging of mouse organ tissues and showed distinct tissue morphology with high resolution.     

含氨基聚甲基丙烯酸羟乙酯树脂对胆红素的吸附性能研究

以交联聚甲基丙烯酸羟乙酯树脂为载体,以己二胺和多乙烯多胺为功能基制备了一系列胆红素吸附剂,研究了它们在不同吸附温度、离子强度和胆红素浓度等条件下,对胆红素的吸附性能的影响.研究表明,该类吸附剂对胆红素具有良好的吸附性能,其中以己二胺和质子化己二胺为功能基的吸附剂对胆红素的吸附作用最佳.     

Synthesis of Unsaturated Nine-Membered Ring Ethers (Δ3-Oxonenes) Containing a Z- or E-Configurated Double Bond: Thermodynamic versus Kinetic Control in Palladium-Catalyzed Allylic Cyclizations

Double stereocontrol is achieved in the Pd-catalyzed cyclization of Δ³-oxonene precursors (see reactions outlined below). The configuration of the olefinic double bond and of the allylic carbon center α to the ether oxygen atom is dictated by the configuration of the double bond in the starting compound (E/Z), the Pd ligand (dppe = Ph₂PCH₂CH₂PPh₂), and the reaction time.     

Synthesis of Hypervalent Iodine(III) Reagents Containing a Transferable (Diarylmethylene)amino Group and Their Use in the Oxidative Amination of Silyl Ketene Acetals

The preparation of some hypervalent iodine reagents containing a transferable amino group derived from benzophenone imine derivatives is reported. The reagents can be readily prepared and stored as a bench‐stable solid, and were successfully used in the transition‐metal‐free oxidative amination of silyl ketene acetals to afford the corresponding α‐amino esters, the benzophenone imine moieties of which could be easily hydrolyzed, thereby leading to the formation of primary amines.     

Localization of Fatty Acyl and Double Bond Positions in Phosphatidylcholines Using a Dual Stage CID Fragmentation Coupled with Ion Mobility Mass Spectrometry

A high content molecular fragmentation for the analysis of phosphatidylcholines (PC) was achieved utilizing a two-stage [trap (first generation fragmentation) and transfer (second generation fragmentation)] collision-induced dissociation (CID) in combination with travelling-wave ion mobility spectrometry (TWIMS). The novel aspects of this work reside in the fact that a TWIMS arrangement was used to obtain a high level structural information including location of fatty acyl substituents and double bonds for PCs in plasma, and the presence of alkali metal adduct ions such as [M?+?Li]⁺ was not required to obtain double bond positions. Elemental compositions for fragment ions were confirmed by accurate mass measurements. A very specific first generation fragment ion m/z 577 (M-phosphoryl choline) from the PC [16:0/18:1 (9Z)] was produced, which by further CID generated acylium ions containing either the fatty acyl 16:0 (C₁₅H₃₁CO⁺, m/z 239) or 18:1 (9Z) (C₁₇H₃₃CO⁺, m/z 265) substituent. Subsequent water loss from these acylium ions was key in producing hydrocarbon fragment ions mainly from the α-proximal position of the carbonyl group such as the hydrocarbon ion m/z 67 (+H₂C-HC?=?CH-CH?=?CH₂). Formation of these ions was of important significance for determining double bonds in the fatty acyl chains. In addition to this, and with the aid of ¹³C labeled lyso-phosphatidylcholine (LPC) 18:1 (9Z) in the ω-position (methyl) TAP fragmentation produced the ion at m/z 57. And was proven to be derived from the α-proximal (carboxylate) or distant ω-position (methyl) in the LPC.     

C-Alkylation of Peptides Containing Aminomalonate and (Amino)(cyano)acetate Residues

N-Acetyl-, N-[(tert-butoxy)carbonyl](Boc)-, and N-[(benzyloxy)carbonyl](Z)-protected tri-, penta-, and heptapeptide methyl esters, 1 – 8 , with a central aminomalonate (Ama) (allyl, methyl, benzyl, or tert-butyl) or (amino)(cyano)acetate (Aca) residue have been prepared by conventional techniques (Schemes 4 – 6). The new peptides with acidic backbone-bound CH groups can be C-alkylated with primary alkyl, allyl, and benzyl halides, under mildly basic conditions (1 equiv. MeONa or t-BuOK in THF); also, they can be added to Michael acceptors such as acrylates, acrylonitrile, methyl vinyl ketone, or nitrostyrene (catalytic amounts of alkoxide bases in THF) (Schemes 7 – 16). In most cases, the products, 48 – 100 , are formed in excellent yields (average of 77%); one of the epimeric products prevails (2 : 1 to > 20 : 1), and the epimers have been separated, isolated in pure form, and fully characterized (without configurational assignments); addition of the co-solvent 3,4,5,6-tetrahydro-1,3-dimethylpyrimidin-2(1H)-one (DMPU) or of LiBr may improve or even reverse the ratio of epimeric products formed; the heptapeptide derivative 8 had to be solubilized for alkylations in THF by the addition of 30 equiv. of LiBr. Cleavage of the Ama groups (benzyl with H₂/Pd-C, t-Bu with HCl/Et₂O) gave carboxylate derivatives which are actually peptides containing the alkylated aminomalonic acid, the lower homolog of aspartic acid, as residue in the central position. These acids are quite resistant to decarboxylation which had to be achieved by heating at reflux in THF in the presence of 2 equiv. of LiBr and of catalytic amounts of pyridine (Schemes 17 and 18). A one-step removal of the allyl aminomalonate group is possible with Pd/PPh₃/formate (Scheme 19). The resulting peptides, 101 – 115 , were formed as separable 1 : 1 mixtures of two epimers. The CN group of the alkylated Aca residue can be removed reductively (Na/NH₃; Scheme 20). The value of the new method is compared with that of existing methods of peptide-backbone modification.     

Poly(Aryl Ether)s from a Novel Biphenol Monomer Containing a Dicyanoarylene Group

Abstract

The preparation of a novel biphenol, 1,4-bis(4-hydroxyphenyl)-2,3-dicyanonaphthalene, from phenolphthalein is described. This biphenol was prepared in high yield in a four-step reaction sequence. The biphenol can be polymerized with activated dihalides such as 1,2-bis-(4-fluorobenzoyl)-3,4,5,6-tetraphenylbenzene, bis(4-fluorophenyl) sulfone, and 4,4′-dichlorobenzophenone to give high molecular weight amorphous poly(aryl ether)s. The polymers have glass transition temperatures ranging from 284 to 319°C and are easily cast into flexible, colorless, and transparent films. The 5% weight loss temperatures of these polymers, by thermogravimetric analysis in air and nitrogen, are all above 500°C.     

P-C Bond Cleavage in Platinum Complexes Containing bis (Diphenylphosphino) Methane Promoted with a Phase-Transfer Catalyst

With a phase-transfer catalyst, Pt-dppm (dppm = Ph₂PCH₂PPh₂) complexes undergo basic hydrolysis, in which a dppm ligand is hydrolyzed to produce PPh₂Me and PPh₂OH (or PPh₂O). The ease of this hydrolysis reaction depends partly on the molecular charges of the metal complexes. Hydrolysis of neutral [Pt(dppm)(L-L)] (L-L = S₂CO², S₂P(O)(OEt)^2? and mnt = S₂C₂(CN)₂^2?) is slower than that of monocationic [Pt(dppm)(L′-L′)]Cl (L′-V = S₂CNEt₂-, (CH₂)₂S(O)Me and acetylacetonate) compounds. Among the neutral compounds, hydrolysis of [Pt(dppm)(mnt)] is more rapid than that of the other two. These results are rationalized according to the ease with which partial positive charges are induced on the dppm phosphorus atoms. The steric effect due to ligands trans to dppm also influences the rate of hydrolysis of Pt-dppm compounds. When trans ligands are Ph₂P(CH)₂PPh₂, Ph₂P(CH₂)₃PPh₂ and (Ph₂PO₂)H, no hydrolysis of dppm occurs. Hydrolysis of Pt-dppm compounds depends further on the concentrations of both the phase-transfer catalyst and OH^? ions. All these results are consistent with nucleophilic attack of OH^? on dppm phosphorus atoms to release strain in the Pt-dppm ring.     

Facile and highly stereoselective one-pot synthesis of either (E)- or (Z)-nitro alkenes

Aliphatic aldehydes were reacted with nitro alkanes in the presence of catalytic amounts of piperidine over 4 A molecular sieves. Simply by changing reaction conditions (solvent and temperature) it is possible to control the stereochemical outcome of the reactions, obtaining pure (E)- and (Z)-nitro alkenes in high to excellent yields. The role of molecular sieves on the stereochemical control seems crucial in addition to that of piperidine, especially for the synthesis of the Z isomer.     

Synthesis and Photosensitive Properties of Poly(aryl imino) Containing Azobenzene Group (PAI-A)

Using 4,4′‐dibromobenzophenone and 4,4′‐diaminoazobenzene as monomers, poly(aryl imino) containing azobenzene unit (PAI‐A) was synthesized via palladium‐catalyzed amination, and structurally characterized by means of FT‐IR, ¹H NMR spectra and elemental analysis, the results of which show an agreement with the proposed structure. The UV absorption spectra were tested under different conditions. Additionally, differential scanning calorimetry (DSC) and thermogravimetric (TG) measurements show that PAI‐A possesses high glass transition temperature (T_g>176°C) and good thermal stability with high decomposition temperatures in nitrogen atmosphere (T_D>410°C).