片段法合成抗骨质疏松多肽药物特立帕肽

将特立帕肽序列中的34个氨基酸分成4个片段:1-11、 12-16、 17-24和25-34;以Wang Resin（王树脂）为固相载体制得25-34肽树脂;以CTC Resin（2-氯三苯甲基氯树脂）为固相载体制得1-11、 12-16和17-24等3个片段的全保护肽,然后将3个片段的全保护肽按照肽序依次缩合到25-34的肽树脂上,经三氟乙酸切割并脱除侧链保护基得特立帕肽粗品,再经液相色谱纯化得特立帕肽,纯度大于99%,总收率达33%,其结构经MS(ESI)确证。     

微波促进催产素和赖氨加压素环肽的固相合成

以Rink Amide-MBHA树脂为载体, 采用Fmoc/tBu正交保护固相合成策略, 运用微波照射促进, 先快速高效地合成得到载有催产素或赖氨加压素还原型多肽的树脂, 再将连接在树脂上的各还原型多肽分别在微波促进条件下和常温条件下环合形成二硫键制得环肽, 最后用Reagent K试剂将环肽从树脂上裂解下来得到目标多肽的粗品. 利用HPLC法测定不同固相环合条件下得到的多肽粗品纯度, 结果显示经微波促进固相环合得到的多肽粗品纯度明显高于常温条件下得到的多肽粗品纯度. 粗品最后经过反相制备高效液相系统纯化并冻干得到目标多肽纯品, 通过电喷雾质谱法测定了制得的还原型多肽及相应环肽的分子量, 验证了它们的结构.     

片段缩合法合成亮丙瑞林

将亮氨酸作为C末端氨基酸,采用片段缩合策略(2+7)合成亮丙瑞林.液相法合成困难序列Fmoc-Arg(Pbf)-Pro-NHEt时,以DIC为缩合试剂,THF作为溶剂,Pro-NHEt·HCl与Fmoc-Arg(Pbf)-OH的物质的量比为1:1.25,产率可达84.8%.采用固相法合成的全保护七肽片段产率为81.3%.全保护的七肽片段与Arg(Pbf)-Pro-NHEt在液相中缩合时,以DMF:DMSO(V:V=1:1)为溶剂,HATU/HOBt/DIEA为缩合剂,得全保护的九肽.切割侧链后得到目标产物亮丙瑞林.     

六胜肽片段的液相合成及组装研究

六胜肽是一种药妆肽,序列为Ac-Glu-Glu-Met-Gln-Arg-Arg-NH2,是相对安全的类肉毒素活性物质.拟用液相方法分别合成片段A[Ac-Glu(Ot Bu)-Glu(Ot Bu)-Met-OH]和片段B[H-Gln(Trt)-Arg-Arg-OH],然后将两个片段在固相载体上进行组装,经切割、纯化得到六胜肽产品,纯度大于98%,片段组装的收率为65%,并对组装反应的条件进行分析和讨论.该方法结合了固相和液相合成的优点,是一种成本低廉、收率较高和周期较短的六胜肽合成方法.     

Rink Amide树脂结构对多肽合成的影响研究

研究了Rink Amide树脂取代度、溶胀度及肽链的长度不同对肽合成收率的影响,并对影响Rink Amide树脂溶胀度的因素进行了研究,结果表明,合成长肽时低取代度、高溶胀度的Rink Amide树脂能获得较好的肽收率。     

多肽片段连接方法及肽硫酯和肽醛的合成*

本文综述了多肽和蛋白质合成中的片段连接方法,这是近年来多肽和蛋白质合成领域中方法学上的重要进展.该方法使用非保护的多肽片段,无需酶或化学活化试剂,在缓冲溶液中能够高产率地获得多肽和蛋白质.还介绍了与多肽片段连接有关的肽硫酯和肽醛的合成方法.     

(9-叔丁氧羰氨酰基氧甲基)芴-2-乙酰二苯甲胺树脂的制备及其在固相合成保护肽段中的应用

以芴为原料经羟甲基化, 乙酰化. 付氏反应和改良的Clemmensen还原等一系列反应合成了(9-叔丁氧羰氨酰基氧甲基)芴-2-乙酰二苯甲胺树脂. 它可作为固相合成保护肽段时的载体. 用这一新载体, 合成了大鼠转化生长因子α(γ-TGF-α)中的1至7的保护七肽片断段. 总收率可达50%.     

反相高效液相色谱/电喷雾质谱法分析化学合成七肽粗产物

利用RP—HPLC／ESI—MS直接分析用芴甲氧羰基(Fmoc)固相多肽合成方法在PHB树脂上偶联合成的一个七肽(H2N—Tyr—Val—Asn-Thr-Asn—Met—Gly—COOH,Mr797．3)粗产物。RP—HPLC显示合成粗产物含有1个主成分,4个次要成分和多个微量成分;与之联用的电喷雾质谱则同步准确地测定出各成分的分子量(m／z)并自动对各主要成分的化学结构进行了串联质谱分析。结果证明,粗产物中的主成分即为目标七肽,另外几个主要副产物为七肽的氧化产物或残缺肽。     

固相多肽合成中Dmab保护基的脱除研究

在固相多肽合成中,Dmab作为羧基保护基具有脱保护条件温和、步骤简便、选择性高的特点,但有时脱保护效率并不稳定.为此,基于Fmoc/t Bu/Dmab三维正交保护策略,利用固相多肽合成技术设计并合成了4个肽树脂,对固相多肽合成中Glu和Asp主链和侧链羧基的Dmab保护基脱除规律进行了研究.结果显示,树脂上α-ODmab的脱保护快速、完全,β-ODmab和γ-ODmab脱保护反应较慢,可以检测到相应的中间产物(4-氨基苄酯肽),推测脱保护效率由快到慢依次为α-ODmabβ-ODmabγ-ODmab.该结果表明Dmab作为α-COOH保护基具有较高的应用价值,但用于β-COOH和γ-COOH保护时,其脱保护条件尚不成熟.     

反相高效液相色谱与质谱联用分析合成七肽的消旋产物

采用反相高效液相色谱(RP-HPLC)与质谱(MS)联用技术对固相法化学合成七肽(H2N-PFNSLAI-COOH,M r 760.9)时出现的消旋产物进行了分析。根据弱疏水性合成七肽粗品特性,提出了充分利用吸附和分配双重保留机制的“早期吸附”概念,以此优化色谱条件得到4个峰形良好的色谱峰;质谱分析表明:4谱峰具有相同的m/z761.5[M H] 值,对每一消旋产物进行在线多肽测序,并利用串联质谱(MSn)谱图叠加的方法,得到b轴和y轴两套片段信息,成功确定了合成七肽的4个消旋产物。     

自组装多功能反应器固相合成依非巴特

采用集反应、搅拌、鼓泡、N2气保护和过滤五重功能的自组装反应器,研究了树脂种类、溶剂、缩合试剂和反应时间对环肽依非巴特产率的影响。结果表明,以Rink Amide AM树脂为固相载体,HBTU/HOBt/DIEA为肽键缩合剂,DMF为溶剂,反应2 h,粗肽得率高达86.6%,经液相色谱纯化后纯度达98%以上。     

Traceless solid-phase synthesis of 1,2,4-triazoles using a novel amine resin

[reaction: see text]. A solid-phase route to 5-aryl-3-arylthiomethyl-1,2,4-triazoles has been developed that permits the incorporation of two elements of diversity. The heterocycle was constructed upon a novel 4-benzyloxy-2-methoxybenzylamine (BOMBA) resin, from which traceless cleavage could be effected with dilute TFA. A library of 96 triazoles was produced with an average yield of 26% (84% yield per step) and an average purity of 80%. In a direct comparison, the new BOMBA resin proved to be markedly superior to Rink Amide resin for this application.     

Base catalyzed intramolecular transamidation of 2-aminoquinazoline derivatives on solid phase

A novel intramolecular cyclo-elimination via transamidation on the Rink Amide AM resin under mild basic conditions is presented. The methodology led to the synthesis of an important class of cardiotonic agents: imdiazo- and pyrimido-quinazolines from the corresponding 2-aminoquinazoline hydrobromide salt under mild basic conditions. NMR based titration studies revealed the role of hydrobromide as a molecular switch, which on removal triggers the cyclisation of aminoquinazoline to tricyclic structures. The main advantage of transamidation under basic conditions over the TFA cleavage is the recyclability of the resin obtained after cyclo-elimination. This has been demonstrated by successive synthesis of four structurally diverse imidazoquianzolin-2-ones using the same batch of resin without any cross contamination.     

Solid Phase Synthesis of 3‐Toluenesulfonylglutarimides

A novel route for the synthesis of 3‐toluenesulfonylglutarimides on a solid support is described. The cyclization step involves stepwise [3+3] strategy of Rink Amide resin bound onto an α‐toluenesulfonyl group with various α,β‐unsaturated esters.     

A new method for the preparation of 2-chlorotrityl resin and its application to solid-phase peptide synthesis

2-Chlorotritylchloride (2-CTC) resin was prepared efficiently from 1% DVB-crosslinked polystyrene resin and 1-chloro-2-(dichloro(phenyl)methyl)benzene, which was easily obtained from 2-chlorobenzophenone. This 2-CTC resin showed excellent properties as a support for solid-phase peptide synthesis. Four peptide fragments were obtained in high purity using the resin.     

Geometry Optimization and Quantum-Chemical Calculations of Normal Vibrations for Methyl-N-methylurethane and Methyl-N-(α)Naphthylurethane

The equilibrium geometries and IR frequencies of methyl-N-methylurethane (MU) and methyl-N-()-naphthylurethane (MNU) were calculated by various quantum-mechanical methods: ab initio using the HF/6-31G* basis set, AM1 and PM3 semiempirical methods, and density functional theory (DFT) at the PBE/TZ2P level using MOPAC 6.0, GAMESS, and PRIRODA software. The experimental and calculated frequencies in the range 4000-60 cm^-1 are compared and analyzed. The comparison was performed based on well-studied characteristic urethane bands: Amide A, Amide I, Amide II, Amide III, Amide IV, and Amide V. The calculated frequencies of MU and MNU were compared with the experimental frequencies; the best agreement was obtained by using the DFT method. Other methods require scaling factors. For ab initio calculations, only one linear multiplier, a = 0.889, may be introduced. To obtain agreement with experiment in AM1 and PM3 methods, one must take different scaling factors for different spectral regions. All calculations confirm the previous conclusions that urethane fragment vibrations are characteristic and weakly interacting with methyl group and naphthyl ring vibrations.     

A new highly efficient method for the synthesis of trans-tetrahydro-3,4-furandiamine

A new four-step, highly efficient synthesis of trans-tetrahydro-3,4-furandiamine is described. Nitromercuration of 2,5-dihydrofuran with sodium nitrite and mercuric chloride in aqueous solution followed by base catalyzed elimination yielded 3-nitro-2,5-dihydrofuran which was aminated with ammonium hydroxide to give trans-tetrahydro-4-nitro-3-furanamine. Catalytic reduction of this material afforded the desired product 5 in 37% overall yield.     

Tailoring ultraresins based on the cross-linking of polyethylene imines. Comparative investigation of the chemical composition, the swelling, the mobility, the chemical accessibility, and the performance in solid-phase synthesis of very high loaded resins

Ultraresins have been prepared from polyethyleneimines and cross-linking molecules and have been provided with various degrees of cross-linking. The total nitrogen loading and the loading with secondary and with tertiary amines have been determined in all products. Nitrogen loadings of the novel resins were up to 15 mmol/g, reactive secondary amines up to 13.8 mmol/g. In addition to the exceptionally high loading, the novel resins displayed efficient swelling volumes in polar and nonpolar solvents. The mobility of resin-bound species as determined by EPR-spectroscopy, depending on the amount of cross-linker, indicated good flexibility and reactivity of this resin type. The novel, high-loaded resins have been investigated subsequently in solid-phase synthesis. The Rink amide linker and two different hydroxy linkers (hydroxyacetamide, HMPB) have been attached to the resin. Despite the high loadings, the secondary amines were easily accessible and could be functionalized exhaustively. Reactivity of the linker-coupled resins was found to be closely related to the resin composition. Increased resin cross-linking led to reduced swelling, reduced mobility, and reduced reactivity in the synthesis of a medium-sized model peptide. As the result of the systematic investigation of structure-property relations in Ultraresins, a support material was identified that combined high reactivity and a mobility in the range of the extremely flexible Tentagel supports. In the optimized Ultraresin, >95% of all available secondary nitrogens could be coupled with Rink linker or with the small 2-hydroxyacetamide anchor, resulting in loadings from 2.7 to 6.8 mmol/g, respectively. A resin with an attached HMPB linker and spacer delivered analytically pure peptides in solid-phase synthesis, fully exploiting the exceptionally high loadings.     

Facile solid phase synthesis of 1,2-disubstituted-6-nitro-1,4-dihydroquinazolines using a tetrafunctional scaffold

Solid phase synthesis of 1, 2-disubstituted-6-nitro-1,4-dihydroquinazolines is described. The new tetrafunctional scaffold N-Alloc-3-amino-3-(2-fluoro-5-nitrophenyl)propionic acid was prepared by nitration of 3-amino-3-(2-fluorophenyl)propionic acid. The scaffold was anchored to Rink resin via its carboxylic group and treated with primary amines to displace the arylfluorine followed by cyclization with aryl isothiocyanates in the presence of DIC upon Alloc deprotection to afford 1,2-disubstituted-6-nitro-1,4-dihydroquinazolines in high yield.