排序方式: 共有12条查询结果,搜索用时 15 毫秒
1.
Isidore P. Decostaire 《Tetrahedron letters》2006,47(39):7057-7060
An aminooxy-containing peptide, the nucleophile partner for oxime ligations, is usually grafted on a NH2-peptide resin by activating a protected aminooxyacetic acid as an active ester. Here, we have shown that its subsequent coupling to NH2-peptide resin competes with the overacylation of the -NH-O- nitrogen and that the overacylation level increases with the basicity of the reaction mixture. Moreover, we found that overacylation is prevented when the COOH of the Aoa-derivatives is engaged in an amide bond. 相似文献
2.
Stephan Pritz Yvonne Wolf Clementine Klemm Michael Bienert 《Tetrahedron letters》2006,47(33):5893-5896
The phosphonium-type coupling reagent PyBOP, when applied to the synthesis of peptide nucleic acid (PNA) oligomers, was found to form O4-phosphonium compounds of the nucleobase guanine which can be converted into C4-modified guanine-derived PNAs by nucleophiles. 相似文献
3.
Dominique Lelièvre 《Tetrahedron letters》2008,49(25):4016-4019
In the course of the chemical synthesis of human protein mitogaligin, we present here a simple method to prepare peptide thioesters using Fmoc chemistry. The hydroxyl side chain of serine was reacted with a trichloroacetimidate Wang resin to anchor it on solid phase. After peptide elongation and orthogonal unmasking of the C-terminus, the amino thioester was introduced under optimized conditions to avoid epimerization. 相似文献
4.
Keiichi Yamada Izuru NagashimaMasakazu Hachisu Ichiro MatsuoHiroki Shimizu 《Tetrahedron letters》2012,53(9):1066-1070
Cyclic RGD peptides are potent antagonists for the αvβ3 integrin receptor. In this Letter, microwave-assisted solid-phase synthesis of cyclic RGD peptides is described. In a coupling reaction between Fmoc-Arg(Pbf)-OH and high-loading H-Gly-Trt(2-Cl) resin, multiple coupling reactions were required for completion under the conventional HBTU activation. We found that the use of COMU, a new coupling reagent, under microwave heating to 50 °C accelerated the reaction even inside the resin. This method was applicable to the synthesis of linear pentapeptides, H-Asp(OtBu)-Xxx-Yyy-Arg(Pbf)-Gly-OH (Xxx = d-Phe(p-Br) or d-Tyr, Yyy = Lys(Boc) or MeVal). Cyclization of these peptides followed by deprotection gave the desired cyclic RGD peptides with high purity. 相似文献
5.
This communication demonstrates the formation of an unusual nucleophilic ring opening of benzoxazinones by 1,8-diazabicycloundec-7-ene (DBU). This observation contradicts the intrinsic feature of a hindered nonnucleophilic base like DBU. Confirmation of the product was achieved via single-crystal X-ray diffraction studies. 相似文献
6.
Marco Molteni 《Journal of fluorine chemistry》2004,125(11):1735-1743
Peptides modified with fluoroalkyl functions in key backbone positions have been scarcely studied so far. Thus, little is known about their synthesis, their structural and physico-chemical properties, and their biological features. Our interest in this field of research led to the development of stereocontrolled synthetic protocols, both in solution and in solid phase, for many different fluoroalkyl peptidomimetics, some of which are overviewed in this paper: (a) ψ[CH(CF3)NH]-peptide mimics holding a great potential as hybrids between natural peptides and hydrolytic transition state analogs; (b) trifluoromethyl (Tfm) malic peptidomimetics as micromolar inhibitors of some matrix metalloproteinases; (c) bis-Tfm analogs of Pepstatin A, that are nanomolar and selective inhibitors of the protozoal aspartyl protease Plasmepsin II. 相似文献
7.
Jeong Kyu Bang 《Tetrahedron letters》2004,45(1):99-102
Linear and cyclic olefin peptides containing the substrate sequence for human T-cell leukemia virus type-1 (HTLV-1) were efficiently synthesized on a solid support using the Horner-Emmons reaction. The precursor peptide aldehyde was prepared by oxidation of the corresponding peptide alcohol with Dess-Martin periodinane. The oxidation reaction proceeded quantitatively on a cross-linked ethoxylate acrylate resin (CLEAR) support instead of a polystyrene-based support. Cyclization on the solid support was achieved via an amide bond formation mediated by EDC/HOAt to yield a single major product. The linear olefin peptide was cleaved by HTLV-1 protease at the scissile site, whereas the cyclic olefin peptide functions as a competitive inhibitor rather than a substrate. 相似文献
8.
This work is part of our studies on the reactivity and crystal engineering of (1-diaminomethylene)thiourea (HATU). Structure and other properties of the selected products of the interaction of HATU with transition metal halides, also in the presence of 3% hydrogen peroxide as an oxidizing agent, have been investigated ((1) di-μ-((1-diaminomethylene)thiouron-1-ium)-κ4S:S-bis[chlorido((1-diaminomethylene)-thiouron-1-ium-κS)copper(I)] tetrachloride [(C2H7N4S)4CuI2Cl2]Cl4, (2) catena(bis(3,5-diamino-1,2,4-thiadiazol-2-ium)-bis(μ2-chlorido)-chloridocuprate(II)) [(C2H6N4S)2(Cu2Cl6)]∞, (3) 3,5-diamino-1,2,4-thiadiazol-2-ium pentachloridoferrate(III) (C2H6N4S)2[FeCl5], (4) 3,5-diamino-1,2,4-thiadiazol-2-ium chloride) (C2H6N4S)Cl, (5) 3,5-diamino-1,2,4-thiadiazol-2-ium tetrachloridozincate(II) (C2H7N4S)2[ZnCl4]. For (2) also magnetic properties have been characterized. Compound (3) contains unusual pentachloridoferrate(III) anions. 相似文献
9.
Orin Inggriani Napitupulu Dadan Sumiarsa Toto Subroto Nurlelasari Desi Harneti Unang Supratman 《合成通讯》2019,49(2):308-315
Cyclo-PLAI was successfully synthesized using a combination of solid- and solution-phase methods. This current synthesis was found to be faster than the previously reported synthesis for the cyclic peptide. The linear precursor was synthesized on 2-chlorotrityl resin with Fmoc/t-Bu strategy. HATU/HOAt was employed as the coupling reagent in the amide bond formation on the resin. Cyclization of the linear precursor was experimented with HATU/HOAt reagents with different conditions. However, the linear precursor was best cyclized using HATU reagent in DIPEA by stirring the reaction mixture at 0?°C for 1?h and followed by stirring the reaction mixture at room temperature for 30?min, giving the cyclic product in 70% yield (calculated from the linear peptide). Both linear and cyclic products were characterized using HR-TOF-ESMS, 1H-NMR, 13C-NMR, and compared with previously reported spectral data for the cyclic product. 相似文献
10.
Chen Liang Mira A.M. Behnam Tom R. Sundermann Christian D. Klein 《Tetrahedron letters》2017,58(24):2325-2329
Phenylglycine-containing peptides have broad applications in medicinal chemistry, but their synthetic accessibility is complicated by the risk of epimerization during solid-phase peptide synthesis (SPPS). Phenylglycine is therefore often considered a troublesome residue. This work studies the extent of Phg racemization under different Fmoc-SPPS reaction conditions. It is shown that the base-catalyzed coupling of Fmoc-Phg is the critical step for racemization. However, racemization can be reduced to a negligible level if DEPBT or COMU combined with TMP or DMP are employed during this step. Resin-bound peptides are remarkably resistant against epimerization during extended incubation under basic conditions and the free peptides were stable in buffer solutions used for biological assays. 相似文献