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.     

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…     

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．     

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。     

(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。     

Structural characterization of folded pentapeptides containing centrally positioned β(R)Val, γ(R)Val and γ(S)Val residues

A cylindrical pore of ～7.5 Å diameter containing a one-dimensional water wire, within the confines of a hydrophobic channel lined with the valine side chain, has been observed in crystals of the peptide Boc–d-Pro-Aib-Val-Aib-Val–OMe (1) (Raghavender et al., 2009, 2010). The synthesis and structural characterization in crystals of three backbone homologated analogues Boc–d-Pro-Aib-β³(R)Val-Aib-Val–OMe (2), Boc–d-Pro-Aib-γ⁴(R)Val-Aib-Val–OMe (3), Boc–d-Pro-Aib-γ⁴(S)Val-Aib-Val–OMe (4) are described. Crystal structures of peptides 2, 3 and 4 reveal close-packed arrangements in which no pore was formed. In peptides 2 and 3 the N-terminus d-Pro-Aib segment adopted conformations closely related to Type II′ β-turns, while residues 2–4 form one turn of an αβ right-handed C₁₁ helix in 2 and an αγ C₁₂ helix in 3. In peptide 4, a continuous left-handed helical structure was observed with the d-Pro-Aib segment forming a Type III′ β-turn, followed by one turn of a left-handed αγ C₁₂ helix.     

Asymmetric Conjugate Addition of Alcohols to (R)-(-)-5-[(1R,2S,5R)-Menthyloxy]-2-(5H)-Furanone

(R)-(-y5-[(IR,2S,5R)-menthyloxy](1)isausefulchiralsynthonreadilypreparedonatWo-stepprocedure-l']FindingsoffuranoneringsexistingascomponentSofsomenaturalproductSI'laswellastheiractivereactivityl']havestimu1atedeXtensiveresearchofitSasymmetricreactionswhichincludeDiels-Alderreactions,l']l,3-dipo1arcycloadditions,['1Michaelauditionsl5]andconjugateedditionsofaminesl']andmercaPtans.g4:,::7f:7':theseadductsledtovariousmultifunctionalhomochiralbuildingblockssuchas2-alkyl-l,4-butanediols,I'l2-aI…     

Asymmetric synthesis of (?)-(R)-massoia lactone, (R)-δ-decalactone, and (+)-(3R,5R)-3-hydroxydecano-5-lactone. Formal synthesis of verbalactone

A simple and efficient procedure for the asymmetric synthesis of (?)-(R)-massoia lactone, (R)-??-decalactone, and (+)-(3R,5R)-3-hydroxy-1,5-decanolide is described. Verbalactone was synthesized using Heck allylation at the key stage of construction of the carbon skeleton.     

Synthesis of (4R)-α-Terpineol

Thesynthesisofopticallyactivecompoundsisanimportantissueinmodemorgan-icchendstry-7-Terpineol,anaturalproductisolatedfrompetitgrainoil,longleafpineoi1andcaeputoill'J,hasbeenasynthetictargetduringthecourseofourstudiesontheasymmetriccatalisedDiels-AlderreactionlvInthispaper,l-phenylsulfOnyl-3-buten-2-one(l)wasusedasthesulfOnyl-functionalizedche1atingenoneforthesynthesischiral2-Terpineol(5)byaasymmetriccata1isedDiels-Alderreaction.TherouteforthesynthesisofopticallyaCtivea-Terpineo1(5)isshownin…     

稀土半导体Cu(In,R)Te_2(R=稀土)的结构和拉曼散射研究

利用稀土元素独特的光、电特性,成功地制备出稀土掺杂的CuIn1-xRxTe2(R=稀土)(CIRT)新型光伏半导体材料。应用X射线衍射、扫描电镜、拉曼散射等进行了相关的晶体结构、显微组织、光性能研究。研究表明:稀土元素的掺杂能够稳定黄铜矿型的晶体结构,点阵常数随稀土元素的掺杂呈现出涨落性。应用Rietveld方法测定原子占位,稀土元素部分替代In占据4b晶位。稀土元素的掺杂导致晶粒团聚现象,并形成柱状或层状单晶颗粒,具有透光性。CuInTe2和CuIn0.9Sm0.1Te2的Eg值分别为1.25和1.32 eV,这表明:CuIn0.9Sm0.1Te2与CuIn1-xGaxTe2具有接近的禁带宽度,适宜做光伏材料。拉曼散射实验证实:稀土元素的添加对于光散射诱发的原子振动频率有较大的影响,使得一些原有频率消失,有助于光谱频段的选择性吸收。     

Asymmetric synthesis of (−)-(R)-sitagliptin

The asymmetric synthesis of (?)-(R)-sitagliptin was achieved in seven steps from commercially available starting materials using the highly diastereoselective conjugate additions of either lithium (R)-N-benzyl-N-(α-methylbenzyl)amide or lithium (R)-N-benzyl-N-(α-methyl-p-methoxybenzyl)amide to tert-butyl 4-(2′,4′,5′-trifluorophenyl)but-2-enoate to install the correct stereochemistry. Subsequent sequential acid-catalysed hydrolysis of the resultant β-amino esters, HOBt/EDC mediated coupling with the triazolopyrazine fragment, and hydrogenolysis gave (?)-(R)-sitagliptin in 43% and 42% overall yields, respectively.     

Interconversion of (R) and (S)-α-hydroxy esters: precursors of (S) and (R)-o-benzyl-α-hydroxylamino acid esters of high optical purity

(R)- and (S)-α-hydroxy esters 5 are interconverted via their triflates 6 in high chemical as well as optical yields by reaction with dimethylformamide. The same triflates are efficiently converted into N-hydroxy-α-amino acid derivatives 7 of high optical purity.     

Synthesis of (R)-(-)-γ-amino β-hydroxy Butyric Acid (GABOB)

An efficient enantiospecific synthesis of a neuromodulator, antiepileplic and hypotensive drug (R)-(-)-γ-amino-β-hydroxybutyric acid (1) starting from (+) tartaric acid is described.     

Synthesis and Characterization of Nickel(Ⅱ) and Copper(Ⅱ) Complexes with Schiff Base (1R,2R)-(-)-Diaminocyclohexane-N,N'-bis(3-tert-butyl-5-(4'-benzoic acid)-salicylidene)

Two homochiral metallosalen complexes,Ni(salen) (salen=(1R,2R)-(-)-diaminocyclohexane-N,N'-bis(3-tert-butyl-5-(4'-benzoic acid)-salicylidene) 1 and Cu(salen) 2,have been synthesized and characterized by IR,microanalysis,TGA,powder and single-crystal X-ray crystallography. Both 1 and 2 crystallize in orthorhombic space group P2_12_12 with Z=4. For 1,α= 12.082(2),b = 15.447(3),c = 18.784(4)(A),V= 3505.7(12) (A)~3,M_r = 731.50,D_c = 1.386 g/cm~3,μ= 0.606 mm~(-1),F(000)=1544,the final GOOF=1.043,R=0.0496 and wR=0.1248 for 4791 observed reflections with Ⅰ> 2σ(Ⅰ). For 2,α=12.181(2),b=15.501(3),c=18.877(4)(A),V= 3564.3(12)(A)~3,M_r=736.33,Dc = 1.372 g/cm~3,μ=0.665 mm~(-1),F(000)=1548,the final GOOF= 1.062,R=0.0575 and wR=0.1508 for 4562 observed reflections with Ⅰ> 20(Ⅰ). The crystal structures of 1 and 2 are isostructural with very similar supramolecular structures. An infinite two-dimensional network is generated by hydrogen bonding interactions and intermolecular π…π interactions.     

Synthesis and Characterization of a Trinuclear Zinc(Ⅱ) Complex with Schiff Base (1R,2R)-(-)-Diaminocyclohexane- N,N'-biscarboxyl-salicylidene)

A homochiral complex, Zn3(Hsalen)2(Py)4(H2O)2 (salen = (1R,2R)-(-)-diamino-cyclohexane-N,N'-biscarboxyl-salicylidene) 1, has been synthesized by solvothermal procedure and characterized by IR, microanalysis, TGA, powder and single-crystal X-ray crystallography. It crystallizes in monoclinic space group P2 with a = 10.9439(7), b = 10.1722(6), c = 27.3450(17), β = 97.5060(10)o, V = 3018.1(3) 3, Z = 2, Zn3(Hsalen)2(Py)4(H2O)2, Mr = 1363.33, Dc = 1.500 g/cm3, F(000) = 1408, μ = 1.257 mm-1, GOOF = 1.042, the final R = 0.0601 and wR = 0.1464 for 10322 observed reflections with I 2σ(I). The coordination polymer 1 possesses a 1D infinite zigzag chain architecture constructed by strong hydrogen bonding interactions and the polymeric chains are further assembled into a 2D supramolecular network structure via C-H···π interactions between the cyclohexane and aromatic rings of the ligand of adjacent chains. Simultaneously, π···π stacking interactions play an important role in forming the 2D supramolecular framework.     

Electrochemical and Theoretical Investigations of the Role of the Appended Base on the Reduction of Protons by [Fe(2) (CO)(4) (κ(2) -PNP(R) )(μ-S(CH(2) )(3) S] (PNP(R) ={Ph(2) PCH(2) }(2) NR, R=Me, Ph)

The behavior of [Fe(2) (CO)(4) (κ(2) -PNP(R) )(μ-pdt)] (PNP(R) =(Ph(2) PCH(2) )(2) NR, R=Me (1), Ph (2); pdt=S(CH(2) )(3) S) in the presence of acids is investigated experimentally and theoretically (using density functional theory) in order to determine the mechanisms of the proton reduction steps supported by these complexes, and to assess the role of the PNP(R) appended base in these processes for different redox states of the metal centers. The nature of the R substituent of the nitrogen base does not substantially affect the course of the protonation of the neutral complex by CF(3) SO(3) H or CH(3) SO(3) H; the cation with a bridging hydride ligand, 1?μH(+) (R=Me) or 2?μH(+) (R=Ph) is obtained rapidly. Only 1?μH(+) can be protonated at the nitrogen atom of the PNP chelate by HBF(4) ?Et(2) O or CF(3) SO(3) H, which results in a positive shift of the proton reduction by approximately 0.15?V. The theoretical study demonstrates that in this process, dihydrogen can be released from a η(2) -H(2) species in the Fe(I) Fe(II) state. When R=Ph, the bridging hydride cation 2?μH(+) cannot be protonated at the amine function by HBF(4) ?Et(2) O or CF(3) SO(3) H, and protonation at the N atom of the one-electron reduced analogue is also less favored than that of a S atom of the partially de-coordinated dithiolate bridge. In this situation, proton reduction occurs at the potential of the bridging hydride cation, 2?μH(+) . The rate constants of the overall proton reduction processes are small for both complexes 1 and 2 (k(obs) ≈4-7?s(-1) ) because of the slow intramolecular proton migration and H(2) release steps identified by the theoretical study.     

Electrochemical and electrocatalytic studies of the N,N′-(1R,2R)-(–)-1,2-cyclohexylenebis(salicylideneiminato)cobalt(II) complex

The electrochemical properties and catalytic activity of a Co(II) complex with the optically active Schiff base derived from (1R,2R)-(–)-cyclohexanediamine and salicylaldehyde have been studied in non-aqueous solutions. When dissolved in deoxygenated non-aqueous solutions, the complex exhibits reversible redox properties for the Co(II)/Co(III) couple. Electrochemical reduction of oxygen and oxidation of cobalt(II) was observed on cyclic voltammograms of solutions containing both dioxygen and the Schiff base-cobalt(II) complex. An anodically formed film on a platinum electrode, studied by means of X-ray photoelectron spectroscopy, revealed the presence of the oxidized Co(III) species. Cyclic voltammetry of oxygenated solutions examined after a period of time indicates an electrochemical activity of coordinated superoxo/peroxo species in the 0.7–1.1 V potential range. In the presence of 4-methyl-1-cyclohexene the cyclic voltammetry curves reveal changes similar to those caused by the removal of oxygen. The GC-MS technique was used to identify some of the products formed by the catalytic oxidation of cyclohexene and 4-methyl-1-cyclohexene. Electronic Publication     

(R)-(S)-α-苯乙胺的立体控制合成

光学活性α-苯乙胺广泛地用作为手性拆分剂,拆分有机酸类;同时又是一种较好的手性助剂,诱导不对称合成反应。过去,该类化合物主要是通过拆分方法得到。近年来发展了不对称合成方法,如肟的不对称还原以及用手