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1.
Fengtian Xue 《Tetrahedron letters》2010,51(18):2536-1366
We report a fast N→O tert-butyloxycarbonyl (Boc) migration of the imide (3R,4R)-tert-butyl 3-((6-(bis(tert-butoxycarbonyl)amino)-4-methylpyridin-2-yl)methyl)-4-hydroxypyrrolidine-1-carboxylate (2) via a base-generated alkoxide. The mechanism of the migration is intramolecular, involving an unusual nine-membered cyclic transition state. 相似文献
2.
Buzhe Xu Yann Hermant Dr. Sung-Hyun Yang Prof. Dr. Paul W. R. Harris Prof. Dr. Margaret A. Brimble 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(62):14101-14107
A de novo solid-phase synthesis of the cyclic lipodepsipeptide daptomycin via Boc chemistry was achieved. The challenging ester bond formation between the nonproteinogenic amino acid kynurenine was achieved by esterification of a threonine residue with a protected tryptophan. Subsequent late-stage on-resin ozonolysis, inspired by the biomimetic pathway, afforded the kynurenine residue directly. Synthetic daptomycin possessed potent antimicrobial activity (MIC100=1.0 μg mL−1) against S. aureus, while five other daptomycin analogues containing (2R,3R)-3-methylglutamic acid, (2S,4S)-4-methylglutamic acid or canonical glutamic acid at position twelve prepared using this new methodology were all inactive, clearly establishing that the (2S,3R)-3-methylglutamic acid plays a key role in the antimicrobial activity of daptomycin. 相似文献
3.
4.
Wenjie Ma Dr. Hongxiang Wu Sha Liu Dr. Tongyao Wei Prof. Dr. Xiang David Li Dr. Han Liu Prof. Dr. Xuechen Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202214053
Chemical synthesis of proteins bearing base-labile post-translational modifications (PTMs) is a challenging task. For instance, O-acetylation and S-palmitoylation PTMs cannot survive Fmoc removal conditions during Fmoc-solid phase peptide synthesis (SPPS). In this work, we developed a new Boc-SPPS-based strategy for the synthesis of peptide C-terminal salicylaldehyde (SAL) esters, which are the key reaction partner in Ser/Thr ligation and Cys/Pen ligation. The strategy utilized the semicarbazone-modified aminomethyl (AM) resin, which could support the Boc-SPPS and release the peptide SAL ester upon treatment with TFA/H2O and pyruvic acid. The non-oxidative aldehyde regeneration was fully compatible with all the canonical amino acids. Armed with this strategy, we finished the syntheses of the O-acetylated protein histone H3(S10ac, T22ac) and the hydrophobic S-palmitoylated peptide derived from caveolin-1. 相似文献
5.
Adenine is a poor substrate for the Mitsunobu process to carbocyclic nucleosides. However, N-6 amino bis-Boc-protected adenine is reported herein to undergo an efficient coupling under these conditions as a result of its increased solubility and the reduced competing nucleophilicity of the free adenine amino substituent. Products from this reaction are readily converted to aristeromycin, neplanocin, and analogs there from, including 5′-homoaristeromycin, a promising antiviral agent. 相似文献
6.
The efficient synthesis of four benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-ω-iodoalkanoates {benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-3-iodopropanoate, benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-4-iodobutanoate, benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-5-iodopentanoate, benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-6-iodohexanoate} from natural or protected l-amino acids is described. 相似文献
7.
Synthesis,Spectral Characterization and Antioxidant Activity of Novel Zafirlukast Sulfonyl Derivatives
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Donka Rajasekhar Doddaga Srinivasulu Chenchugari Sridhar Godlaveti Vijay Narasimha Kumar Peddakonda Ramesh 《中国化学会会志》2016,63(3):267-274
A new series of cyclopentyl 3‐(2‐methoxy‐4‐(piperazine‐1‐carbonyl)benzyl)‐1‐methyl‐1H‐indol‐5‐ylcarbamate sulfonyl derivatives were synthesized by the reaclion of 4‐((5‐(cyclopentyloxycarbonylamino)‐1‐methyl‐1H‐indol‐3‐yl)methyl)‐3‐methoxybenzoic acid (ZAK drug intermediate) with Boc piperazine in the presence of EDC?HCl, HOBt, TEA in DMF followed by deboxylation by using 2N HCl or 35 % HCl in acetone to get an intermediate compound. Further, this compound was treated with various substituted benzene sulfonyl chlorides in the presence of TEA in THF to afford title compounds. All the title compounds were characterized by 1HNMR, 13CNMR, IR and mass spectral data. The title compounds and starting material were evaluated for their antioxidant activity by using the DPPH, H2O2 and NO methods. The results revealed that some of the compounds have shown significant antioxidant activity. 相似文献
8.
Tarak Nath MandalSomnath Roy Samik GuptaBijan Kumar Paul Ray J. ButcherArnold L. Rheingold Susanta Kumar Kar 《Polyhedron》2011,30(9):1595-1603
Four oxovanadium(V) complexes of heterocycle based ditopic ligands PyPzOAP (N-[amino(pyridin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid), PyPzOAPz (N-[amino(pyrazin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid), PymPzOAP (N-[amino(pyridin-2-yl)methylidene]-1-(4,6-dimethylpyrimidin-2-yl)-5-methyl-1H-pyrazole-3-carbohydrazonic acid) and PyPzCAP (5-methyl-1-(pyridin-2-yl)-N′-[1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazide) and a binuclear (di-μ-oxo) oxovanadium(V) complex of the ligand PymPzCAP (1-(4,6-dimethylpyrimidin-2-yl)-5-methyl-N′-[1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazide) have been investigated. The ligands act as uninegative NNO tridentates donors for the VO2+ ion exhibiting their monotopicity. The ligands show varying emission properties due to the presence of fluophoric groups like 1-(2-pyridyl)pyrazole or 1-(2-pyrimidyl)pyrazole. The vanadium(V) complexes show fluorescence quenching with respect to the used ligands to a varying extent. The complexes were characterized by UV-Vis, IR, cyclic voltammetry and X-ray crystallography. 相似文献
9.
Chun-min Zeng John A. Katzenellenbogen Kyla Gallacher C. Richard Lyttle Chris P. Miller 《Tetrahedron letters》2010,51(41):5361-5363
An efficient synthesis of the non-proteinogenic amino acid (2R,3S)-4,4,4-trifluoro(OBn)-threonine is described. Starting with commercially available (S)-Garner’s aldehyde, the desired amino acid was prepared as its hydrochloride salt in five steps and an overall yield of 33% (59% based on recovered starting material). The utility of this unusual amino acid was demonstrated by its elaboration into a potent and selective androgen. 相似文献
10.
The current work aims to design and synthesis a new series of isatin derivatives and greatly enhances their cytotoxic activity. The derivatives 3-((bromophenyl) imino)-1-(morpholino (pyridine) methyl) indolin-2-one, 2-((oxoindoline) amino) benzoic acid, 3-(thiazolo-imino) indolinone, ethyl-2-((oxoindolin-3-ylidene)amino)-benzothiophene-3-carboxylate, 1-(oxoindoline)-benzo[4,5] thieno [2,3-d]pyrimidin-4(1H)-one, ethyl-2-(2-oxoindoline) hydrazine-1-carboxylate, N-(mercapto-oxo-pyrimidine)-2-(oxoindoline) hydrazine-1-carboxamide, N-(oxo-thiazolo[3,2-a] pyrimidine)-2-(oxoindolin-ylidene) hydrazine-carboxamide, 3-((amino-phenyl) amino)-3-hydroxy- indolinone, 3-((amino-phenyl) imino)-indolinone, 2-(2-((oxoindoline) amino) phenyl) isoindolinone, 2-(oxoindoline) hydrazine-carbothioamide, 5′-thioxospiro[indoline-3,3′-[1,2,4]triazolidin]-one, 5′-amino-spiro[indoline-3,2′-[1,3,4]thiadiazol]-2-one and 3-((2-thioxo-imidazo[4,5-b]quinoxaline) imino) indolinone were synthesized from the starting material 1-(morpholino (pyridine) methyl) indoline-2,3-dione and evaluated for their in vitro cytotoxic activity against carcinogenic cells. The new chemical structures were evidenced using spectroscopy (IR, NMR and MS) and elemental analysis. The results show that compounds imidazo[4,5-b]quinoxaline-indolinone, thiazolopyrimidine-oxoindoline, pyrimidine-oxoindoline-hydrazine-carboxamide, spiro[indoline-3,2′-[1,3,4] thiadiazol]-one and spiro[indoline-3,3′-[1,2,4]triazolidin]-one have excellent anti-proliferative activities against different human cancer cell lines such as gastric carcinoma cells (MGC-803), breast adenocarcinoma cells (MCF-7), nasopharyngeal carcinoma cells (CNE2) and oral carcinoma cells (KB). 相似文献
11.
For the first time, an unusal cleavage of N‐tert‐butyloxycarbonyl (N‐Boc) protection from N‐Boc‐protected benzamide under basic conditions in excellent yields is reported. The deprotection involves the N‐Boc emigration from the benzamide to form 2‐O‐Boc group followed by O‐Boc deprotection on the phenyl ring. 相似文献
12.
分别由2-[(2Z)-3-羧基-1-氧代-2-丙烯基]氨基-2-脱氧-1,3,4,6-四-O-乙酰基-β-D-吡喃葡萄糖(1a), 2-[(2-羧基苯甲酰基)氨基]-2-脱氧-1,3,4,6-四-O-乙酰基-β-D-吡喃葡萄糖(2a)和氧化二正丁基锡反应合成了两个新化合物双-{2-[(2Z)-3-羧基-1-氧代-2-丙烯基]氨基-2-脱氧-1,3,4,6-四-O-乙酰基-β-D-吡喃葡萄糖}-二正丁基锡酯(1)和双-{2-[(2-羧基苯甲酰基)氨基]-2-脱氧-1,3,4,6-四-O-乙酰基-β-D-吡喃葡萄糖}-二正丁基锡酯(2), 并经红外光谱、核磁共振(1H, 13C NMR)、质谱初步确定了其结构. 体外抗肿瘤活性结果表明, 化合物1对人肺癌细胞株A-549和人肝癌细胞株BEL-7402的细胞毒活性显示为强效; 而对小鼠白血病细胞株P388和人白血病细胞株HL-60的细胞毒活性为弱效. 化合物2对肿瘤细胞株HL-60, A-549和BEL-7402具有强效的细胞毒活性; 而对肿瘤细胞株P388的作用则为弱效. 克隆基因分析表明化合物1和2在3.82×10-6 和 3.02×10-6 mol/L均具有造血细胞毒性. 相似文献
13.
A novel and simple method for the direct and quantitative determination of L-tryptophan (Trp), L-tyrosine (Tyr) and L-cysteine (Cys) was proposed in this work. Carbon nanofibers (CNFs), made by electrospinning technique, were used to modify carbon paste electrode (CPE) without any treatment to study the electrochemical behaviors of the three amino acids using cyclic voltammetry (CV) and constant potential amperometric method. The results demonstrated that the CNFs modified carbon paste electrode (CNF-CPE) exhibited high electrocatalytic activity and good analytical performance towards the oxidation of the three amino acids. The linear ranges of Trp, Tyr and Cys were 0.1-119, 0.2-107 and 0.15-64 μM with correlation coefficients of 0.9994, 0.9985 and 0.9996, respectively. All the detection limits of the analytes were 0.1 μM (S/N = 3). In addition, the CNF-CPE displayed good reproducibility, high sensitivity and good selectivity towards the determination of the amino acids, making it suitable for the determination of Trp, Tyr and Cys in clinical and medicine. 相似文献
14.
Subhash P. Chavan Cherukupally Praveen Pallavi Sharma U.R. Kalkote 《Tetrahedron letters》2005,46(3):439-441
A short synthetic route to (−)-and (+)-bulgecinine, the amino acid moiety of the bulgecins was achieved from the readily available nonchiral pool starting material cis-2-butene-1,4-diol in which a Claisen orthoester rearrangement and a Sharpless asymmetric dihydroxylation were used as the key steps. 相似文献
15.
Guanghui Deng Yuanyuan Li Yu Zhou Jiang Wang Hualiang Jiang Hong Liu 《Tetrahedron》2008,64(46):10512-10516
The non-proteinogenic amino acid (2S)-2-amino-3,3-bis(4-fluorophenyl)propanoic acid [(S)-1] is a key intermediate required for the synthesis of Denagliptin (2a). Denagliptin is a dipeptidyl peptidase IV (DPP IV) inhibitor that is being developed for the treatment of type-2 diabetes mellitus. A diastereoselective, cost-efficient synthetic procedure for (S)-1 was developed by alkylating a Ni(II) glycine equivalent derived from (S)-2-[(N-benzylprolyl) amino] benzophenone [(S)-BPB]. The alkylated product was then decomposed to isolate the target amino acid (S)-1 (ee >99%) and ligand (S)-BPB, which can be reused in subsequent reactions. The enantiomer (R)-1 and racemate (rac)-1 were synthesized from their corresponding Ni(II) glycine equivalents. Denagliptin diastereomers (2), derived from the key intermediates (S)-1, (R)-1, and (rac)-1 were synthesized, and their dipeptidyl peptidase IV inhibitory activities were investigated. These findings are important in the design and synthesis of DPP IV inhibitors. 相似文献
16.
This work examines the influence of N-protecting groups on the conversion and stereoselectivity of dihydroxyacetone phosphate (DHAP) dependent aldolase-catalyzed aldol additions of DHAP to N-protected-3-aminopropanal. Phenylacetyl-(PhAc-), tert-butyloxycarbonyl- (tBoc-) and fluoren-9-ylmethoxycarbonyl- (Fmoc-)-3-aminopropanal were evaluated as substrates for d-fructose 1,6-bisphosphate aldolase from rabbit muscle (RAMA), and l-rhamnulose-1-phosphate aldolase (RhuA) and l-fuculose-1-phosphate aldolase (FucA), both from Escherichia coli. Using PhAc and tBoc ca. 70% conversions to the aldol adduct were achieved, whereas Fmoc gave maximum conversions of ca. 25%. The stereoselectivity of the DHAP-aldolases did not depend on the N-protected-3-aminopropanal derivative. Moreover, inversion of FucA stereoselectivity relative to that obtained with the natural l-lactaldehyde was observed. Both N-PhAc and tBoc adduct product derivatives were successfully deprotected by penicillin G acylase (PGA)-catalyzed hydrolysis at pH 7 and by treatment with aqueous TFA (6% v/v), respectively. However, the corresponding cyclic imine sugars could not be isolated, presumable due to the presence of a highly reactive primary amine and a keto group in the molecule, which lead to a number of unexpected reactions. 相似文献
17.
Yanjie Xu Ligong Chen Xuemin Duan Yi Meng Meiling Li Guangle Zhao Yang Li 《Tetrahedron letters》2005,46(25):4377-4379
The total synthesis of hirsutellide A 1 was described. The linear hexadepsipeptide precursor 2 was synthesized in 45% yield from N-Boc-Me-Gly by three coupling reactions with DCC, HATU and BOP-Cl, respectively. Macrocyclization was successfully performed on the fully deprotected amino acid 14 with BOP-Cl in 15% yield and with FDDP in 22% yield. 相似文献
18.
A differentially protected C-3 N-sulfinyl, C-2 N,N-(diphenylmethylene) 2,3-diamino ester was employed in the synthesis of the amino piperidine (2S,3R)-(−)-epi-CP-99,994. Key steps in the synthesis included the chemoselective hydrolysis of the C-2 N,N-(diphenylmethylene) group and its reprotection as a dibenzylamino group. 相似文献
19.
Charlotta Naeslund 《Tetrahedron》2005,61(5):1181-1186
The enantiomers of the highly lipophilic α-amino acid m-carboranyl-alanine [3-(1,7-dicarba-closo-dodecaborane(12)-1-yl)-2-aminopropanoic acid], a carborane containing analogue of phenylalanine, have been synthesised via hydroxyamination of the N-acyl derivative formed from 3-(m-carboranyl)propionic acid [3-(1,7-dicarba-closo-dodeca-borane(12)-1-yl)-2-propanoic acid] and Oppolzer's camphor sultam. The enantiomeric excess of both enantiomers of the amino acid was >98%. (S)-Configuration was assigned to the (+)-enantiomer (CH3OH, 589 nm). 相似文献
20.
Absolute rate constants for 1,n-hydrogen atom transfers in some substituted amino acid derived radicals have been determined in benzene through the use of competitive kinetic experiments. Radicals derived from methyl N-(2-iodobenzoyl)-N-(tert-butyloxycarbonyl)glycinate, -alaninate, -leucinate, -tert-leucinate and -phenylglycinate undergo intramolecular 1,5-hydrogen atom transfer to afford the corresponding α-amino acid ester radicals with rate constants in the range: 1.0-4.3 × 107 s−1 at 80 °C. Where abstractable hydrogen atoms exist in the amino acid side-chain, 1,6- and 1,7-translocations are competitive processes. 相似文献