六肽Ile-Thr-(Val)Thz-Ile-Thr-(Val)Thz的合成

从海洋动植物中已分离到近二十个环肽,它们结构新颖,具有强烈的生物活性,引起了广泛的研究。Ascidiacyclamide是从海鞘中分离到的具有细胞毒性的环肽:     

Asymmetric syn-dihydroxylation of γ-substituted (2R)-N-(β,γ-enoyl)bornane-10,2-sultams

Various γ-substituted (2R)-N-(β,γ-enoyl)bornane-10,2-sultams have been examined in diastereoselective OsO₄ syn-dihydroxylation. In contrast to the C(α)-atom, the bornane-10,2-sultam auxiliary exerts a very poor influence on the C(β)-carbon. Spontaneous stereoselective hydrolysis of the minor diastereoisomer (3S,4S)-5c opens the way to enantiomerically pure building blocks.     

Asymmetric synthesis of β-substituted γ-lactams via rhodium/diene-catalyzed 1,4-additions: application to the synthesis of (R)-baclofen and (R)-rolipram

An efficient rhodium/diene-catalyzed asymmetric addition of arylboronic acids to α,β-unsaturated γ-lactams has been developed. The power of this methodology is further demonstrated by the concise synthesis of (R)-baclofen and (R)-rolipram.     

Synthesis and characterization of (R)-miniPEG-containing chiral γ-peptide nucleic acids using the Fmoc strategy

Diethylene glycol (miniPEG)-containing chiral γPNA is considered to be one of the best PNA derivatives. Its preparation is mainly based on the Boc strategy for solid phase peptide synthesis (SPPS), requiring the repeated use of trifluoroacetic acid TFA, which is not suitable for the in situ synthesis of PNA arrays and some other applications under mild conditions. Herein, Fmoc/Cbz orthogonal protected miniPEG-containing chiral γPNA monomers were synthesized, and a 15mer γPNA was prepared using the Fmoc strategy under mild conditions.     

Practical synthesis of (R)-γ-amino-β-hydroxybutanoic acid (GABOB) from (R)-epichlorohydrin

(R)-Epichlorohydrin has efficiently been converted to the hypotensive and antiepileptic compound, (R)-γ-amino-β-hydroxybutanoic acid (GABOB), in six steps in 57% overall yield.     

The Crystallinity of γ-Irradiated Poly(tetrafluoroethylene)

The influence of absorbed -radiation dose over the range 0–220 kGy on the heat of fusion and the crystallinity of industrial specimens of bulk PTFE and PTFE films were studied using the techniques of adiabatic and differential scanning calorimetry. The thermodynamic characteristics of transitions in the interval 287–310 K in the original and the irradiated polymer were determined. Based on the results obtained, a new crystal modification other than the one present in the unirradiated material was assumed to be formed during -irradiation.     

Rhombohedrally distorted γ-brasses Cr(1-x)Fe(x)Ga

A series of rhombohedrally distorted γ-brass structures containing a mixture of magnetically active 3d elements, Cr and Fe, Cr(1-x)Fe(x)Ga, is investigated crystallographically. These structures consist of chains of trans-face-sharing Ga-centered transition metal icosahedra. Neutron powder diffraction specifically on Cr(0.5)Fe(0.5)Ga, which could be prepared as a single phase material, gave lattice constants (11 K) a = 12.5172(2) ? and c = 7.8325(2) ? and a refined composition of Cr(0.502(6))Fe(0.498)Ga = Cr(6.523)Fe(6.477)Ga(13) and revealed partial ordering of Cr and Fe atoms among three crystallographic sites. Magnetic susceptibility and magnetization studies of Cr(0.5)Fe(0.5)Ga showed the onset of magnetic ordering at ca. 25 K. Theoretical calculations suggested both site-energy and bond-energy factors influencing the Cr/Fe distribution. Heteroatomic interactions significantly affect exchange interactions and create low local magnetic moments. Models created to mimic Cr(0.5)Fe(0.5)Ga showed ferromagnetic Fe-Fe and antiferromagnetic Cr-Fe interactions, with an overall ferrimagnetic ordering.     

Asymmetric Synthesis of (-)-(2R,3R,6S)-Irnigaine

Introduction　　Asarelativelynewmemberofnaturalalkaloidswith2 ,6 disubstituted 3 piperidinolskeleton ,irnigaine 1wasisolatedfromthetubersofArisarumVulgare (Araceae)in1995byMelhaouiandBode .1Itsstructureandrelativeconfigurationswereelucidatedby1HNMRstudiesandtheabsoluteconfigurationwasproposedonthebasisofitsopti calrotation .1Soonafterthen ,Meyerandhisco workersreportedthefirstsynthesisof (- ) (2R ,3R ,6S) irni gaineandtheconfigurationconfirmation .Althoughtheirsynthesisroutewasshortan…     

Crystallization of Poly(ethylene adipate) within γ-Phase Poly(vinylidene fluoride) Matrix

The effects of PEA on the γ-phase PVDF crystal structure and the crystallization of PEA within the pre-existing γ-phase PVDF spherulites have been investigated by optical microscopy(OM), infrared spectroscopy(IR) and scanning electron microscopy(SEM). The results demonstrate that the γ-phase PVDF spherulites consist of the lamellae exhibiting a highly curved scroll-like morphology and develop preferentially in PEA-rich blend. With increasing PEA concentration, the scroll diameter increases and the scrolls are better separated from each other. PEA crystallizes first in the interspherulitic region and transcrystalline layer develops. Subsequently, the transcrystalline layer of PEA continues to grow within the γ-phase PVDF spherulites, e.g., in the region between the scrolls, until impinging on other PEA transcrystalline layers or spherulites. The crystallization kinetics results indicate that the growth rate of PEA crystals in the intraspherulitic region of γ-phase PVDF shows a positive correlation with content of PEA, but a negative one with the crystallization temperature of γ-phase PVDF.     

由(S)-和( R )-天冬氨酸合成( R )-和(S)-(2-苄氧乙基)环氧乙烷的改良方法

苄氧乙基环氧乙烷;不对称合成;由(S)-和( R )-天冬氨酸合成( R )-和(S)-(2-苄氧乙基)环氧乙烷的改良方法     

Total Synthesis of 3 (R)-Panaxynol

Panaxynol1,asacommonconstituentofmanyplantparts',wasfirstdescribedbyTakahashietal.2in1964asaconstituentofPanaxyginseng.C.A.MeyershowedinhisBioassayshowedthatpanaxynolhadselectiveinvitrocytotoxicityagainstL-1210',MKI,B-16,andL-929cancercelllinescomparedtonormalcellcultures4.TheabsoluteconfigurationhadbeenestablishedbyLarsenetal.5tobe3R.Hereinwereportthefirsttotalstereoselectivesynthesisofpanaxynol(l).C'-CIafragmentofpanaxynol1wasobtainedaccordingtothefollowingsequencefReagentsandconditio…     

有机溶剂中(R)-醇腈酶催化不对称合成(R)-苯乙醇腈

 研究了来源于杏仁的（R）－醇腈酶在有机溶剂异丙醚中催化苯甲醛与HCN不对称合成（R）－苯乙醇腈，初步探讨了来源于不同杏仁的（R）－醇腈酶的筛选、最适酶量的确定以及底物HCN与苯甲醛的配比、底物浓度、酶的微环境pH和反应温度对不对称合成反应的影响．结果发现，来源于苦杏仁的（R）－醇腈酶优于来源于甜杏仁的（R）－醇腈酶．优化的反应条件为：最适酶量150g／L，HCN与苯甲醛的配比2．5，苯甲醛浓度300mmol／L，酶的微环境pH5．4，反应温度0～5℃．在该优化反应条件下，反应平衡转化率和产物的光学纯度均高达99％以上．     

Antiferromagnetism of poly(3-dodecylthiophene) irradiated by γ-beams

The magnetic properties of poly(3-dodecyl-thiophene) (PDDT) irradiated by -beams have been studied by measuring the magnetic susceptibility and EPR spectra. The irradiated PDDT is characterized, similarly as the non-irradiated one, by an antiferromagnetic course of magnetic susceptibility with a Néel temperature of 237 K. It is suggested that the antiferromagnetic properties of PDDT are caused by transformation of polarons to bipolarons, which takes place at lower temperatures.     

Influence of γ-radiation on iodine-doped poly (3-pentylthiophene)

The influence of -radiation on iodinedoped poly (3-pentylthiophene) has been studied. Doping accompanied by -radiation brings about a decrease of iodine release rate. An increased dopant concentration in the poly (3-pentylthiophene) leads to an increased conductivity, which may be accounted for by the formation of bipolarons in the irradiated and doped samples.     

1(R),2(R)-二(2-苯并咪唑)乙二醇四核铜(Ⅱ) 配合物的合成与晶体结构

合成了一种新配合物1（R）,2（R）－二（2－苯并咪唑）乙二醇四核铜（Ⅱ[Cu4(bbmed)4Cl2L2].Cl2(CH3OH)5(H2O)2(L=MeOH或H2O,Hbbmed=1(R),2(R)-二（2－苯并咪唑）乙二醇,bbmed表示去质子后的配体）简称Cu( Ⅱ）-bbmed)。该晶体经X－射线衍射确定为正交晶系,空间群C221（20）,晶胞参数a=1.7424(5),b=2.4942(7),c=3.8887(11)nm,V=16.900(8)nm^3,Z=4,Dc=1.427g.cm^-3,F(000)=7472,并对它进行了元素分析、IR、^1H NMR及ESR表征。     

Long-term γ-radiolysis kinetics of NO3(-) and NO2(-) solutions

Radiolysis kinetics in NO(3)(-) and NO(2)(-) solutions during γ-irradiation were studied at an absorbed dose rate of 2.1 Gy·s(-1) at room temperature. Air- or argon-saturated nitrate or nitrite solutions at pH 6.0 and 10.6 were irradiated, and the aqueous concentrations of molecular water decomposition products, H(2) and H(2)O(2), and the variation in the concentrations of NO(3)(-) and NO(2)(-) were measured as a function of irradiation time. The experimental data were compared with computer simulations using a comprehensive radiolysis kinetic model to aid in interpretation of the experimental results. The effect of nitrate and nitrite, present at concentrations below 10(-3) M, on water radiolysis processes occurs through reactions with the radical species generated by water radiolysis, (?)e(aq)(-), (?)O(2)(-), and (?)OH. The changes in H(2) and H(2)O(2) concentrations observed in the presence of nitrate and nitrite under a variety of conditions can be explained by a reduction in the radical concentrations. The kinetic analysis shows that the main loss pathway for H(2) is the reaction with (?)OH and the main loss pathways for H(2)O(2) are reactions with (?)e(aq)(-) and (?)OH. Nitrate and nitrite compete for the radicals leading to an increase in the concentrations of H(2) and H(2)O(2). Post-irradiation measurements of H(2), H(2)O(2), NO(2)(-) and NO(3)(-) concentrations can be used to calculate the radical concentrations and provide information on the redox conditions of the irradiated aqueous solutions.     

(S)的(R)吉尼斯蚁警戒素合成方法研究

以樟脑衍生物(-)-莰烷磺内酰胺为原料,经N-酰基莰烷-2,10-磺内酰胺与EtMgBr进行Michael加成反应,用氢化铝锂取代磺内酰胺助剂及溴化锂取代等步骤合成了(S)和(R)吉尼斯蚁警戒素,光学纯度达98%ee。