57Fe NMR spectroscopy of ferrocenes derived from aminoferrocene and 1,1'-diaminoferrocene

Three series of ferrocenes, derived from aminoferrocene Fc-NH2 and 1,1'-diaminoferrocene fc(NH2)2, were studied by 57Fe NMR spectroscopy. A marked decrease in 57Fe magnetic nuclear shielding with respect to ferrocene is observed if the nitrogen atom becomes part of a pi-acceptor linked to one or both cyclopentadienyl rings. In contrast, pi-donor properties of the amino group(s) affect delta57Fe to a much smaller extent. In the case of the fairly rigid structures of 1,3-diaza-2-element-[3]ferrocenophanes, a significant increase of 57Fe nuclear magnetic shielding is observed, in contrast to the corresponding [n]ferrocenophanes with n > 3. Structures of numerous of the ferrocene derivatives have been optimized for the gas phase by calculations (B3LYP/6-311 + G(d,p) level of theory), and 57Fe nuclear magnetic shieldings were calculated using these geometries. There is reasonable agreement in the trends for experimental and calculated data.     

Synthesis of new 1,1'-binaphthyl-based chiral phenylenevinylene dendrimers

Dendrimeric meta-substituted phenylenevinylene moieties have been incorporated on a chiral binaphthyl core, providing new chiral and photoluminescent molecules.     

Synthesis and photoluminescent properties of 1,1'-binaphthyl-based chiral phenylenevinylene dendrimers

New chiral, soluble binaphthyl derivatives that incorporate stilbenoid dendrons at the 6,6'-positions have been prepared. The synthesis of the new enantiopure dendrimers was performed in a convergent manner by Horner-Wadsworth-Emmons (HWE) reaction of the appropriately functionalized 1,1'-binaphthyl derivative (R)-1 and the appropriate dendrons (R)(2n)G(n)-CHO. Different electroactive units were incorporated in the peripheral positions of the dendrons in order to tune both the optical and electrochemical behavior of these systems. Fluorescence measurements on the chiral dendrimers reveal a strong emission with maxima between 409 and 508 nm depending upon the substitution pattern. Finally, the redox properties of the dendrimers were determined by cyclic voltammetry, showing the influence of the functional groups at the peripheral positions of the dendrimer on the redox behavior of these systems.     

氮氧自由基与氨基酸偶联物的设计合成与结构表征

将对甲酰基苯甲酸分别与氨基乙酸甲酯和4-氨基丁酸甲酯生成酰胺后,再分别与2,3-二甲基-2,3-二羟氨基丁烷进行缩合反应,最后经高碘酸钠氧化得到两种氮氧自由基与氨基酸偶联物,并通过IR、EPR、EI-MS和元素分析对目标化合物的结构进行了表征.     

Amino acid based chiral N-amidothioureas. Acetate anion binding induced chirality transfer

N-Amidothioureas generated from amine-dimethylated natural L-phenylalanine and its D-enantiomer bearing a chiral carbon that is by 2 atoms or 3 chemical bonds away from the anion binding site establish chiral communication upon acetate anion binding to the thiourea moiety.     

Synthesis of glycyrrhizic acid conjugates containing L-lysine

Activated esters and N-hydroxybenzotriazole-N,N′-dicyclohexylcarbodiimide (DCC) or N-hydroxysuccinimide-DCC were used to synthesize conjugates of glycyrrhizic acid (GA) with N^ɛ-carbobenzyloxy-L-lysine [Lys(Z)-OH] and its esters containing two or three amino components. It was shown that the conjugate of GA 30-methyl ester with Lys(Z)-OH possessed anti-HIV-1 activity. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 437–441, September–October, 2006.     

Synthesis and structural and photoswitchable properties of novel chiral host molecules: axis chiral 2,2'-dihydroxy-1,1'-binaphthyl-appended stiff-stilbene

Novel photoswitchable chiral hosts having an axis chiral 2,2'-dihydroxy-1,1'-binaphthyl (BINOL)-appended stiff-stilbene, trans-(R,R)- and -(S,S)-1, were synthesized by palladium-catalyzed Suzuki-Miyaura coupling and low-valence titanium-catalyzed McMurry coupling as key steps, and they were fully characterized by various NMR spectral techniques. The enantiomers of trans-1 showed almost complete mirror images in the CD spectra, where two split Cotton effects (exciton coupling) were observed in the beta-transitions of the naphthyl chromophore at 222 and 235 nm, but no Cotton effect was observed in the stiff-stilbene chromophore at 365 nm. The structures of (R)-10 and trans-(R,R)-1 were confirmed by X-ray structural analysis. The optimized structure of cis-1 by MO calculations has a wide chiral cavity of 7-8 A in diameter, whereas trans-1 cannot form an intramolecular cavity based on the X-ray data. Irradiation of (R,R)-trans-1 with black light (lambda = 365 nm) in CH3CN or benzene at 23 degrees C led to the conversion to the corresponding cis-isomer, as was monitored by 1H NMR, UV-vis, and CD spectra. At the photostationary state, the cis-1/trans-1 ratio was 86/14 in benzene or 75/25 in CH3CN. On the other hand, irradiation of the cis-1/trans-1 (75/25) mixture in CH3CN with an ultra-high-pressure Hg lamp at 23 degrees C (lambda = 410 nm) led to the photostationary state, where the cis-1/trans-1 ratio was estimated to be 9/91 on the basis of the 1H NMR spectra. The cis-trans and trans-cis interconversions could be repeated 10 times without decomposition of the C=C double bond. Thus, a new type of photoswitchable molecule has been developed, and trans-1 and cis-1 were quite durable under irradiation conditions. The guest binding properties of the BINOL moieties of trans- and cis-(R,R)-1 with F-, Cl-, and H2PO4- were examined by 1H NMR titration in CDCl3. Similar interaction with F- and Cl- was observed in trans-1 (host/guest = 1/1, Kassoc = (1.0 +/- 0.13) x 103 for F- and (4.6 +/- 0.72) x 102 M-1 for Cl-) and cis-1 (host/guest = 1/1, Kassoc = (1.0 +/- 0.13) x 103 for F- and (5.9 +/- 0.69) x 10 M-1 for Cl-), but H2PO4- interacted differently: the cis-isomer formed the 1/1 complex (Kassoc = (9.38 +/- 2.67) x 10 M-1), whereas multistep equilibrium was expected for the trans-isomer.     

手性膦肽核酸单体的合成

肽核酸是一种潜在的反义和反基因药物。膦肽结构的引入克服了肽核酸低水溶性和低细胞膜通透性等缺点,有利于肽核酸的应用。本研究报道手性磷肽核酸单体的合成。还原氨化方法被用于实现N-Boc,N-Fmoc保护的丙氨醛与甘氨膦酸二酯的偶联,BBC-Cl,FEP等缩合剂被用于实现碱基侧链和母链的高效缩合。     

Synthesis of phosphonodipeptide conjugates of ursolic acid and their homologs

To prepare novel derivatives of naturally bioactive 3β‐hydroxy‐urs‐12‐en‐28‐oic acid (ursolic acid) with unusual properties and broad spectrum of activities, a number of chemical reactions were conducted. First, a variety of α‐aminophosphonates were prepared by a series of reactions involving the three‐component Mannich type reaction as a key step. Second, an array of phosphonodipeptides and their homologs was synthesized through multistep reactions including condensation of phthalic anhydride with glycine or β‐alanine, chlorination of N‐blocked amino acids, coupling of acid chloride with α‐aminophosphonates and sequential hydrazinolysis. Finally, new classes of phosphonodipeptide conjugates of ursolic acid and their homologs were obtained by condensation of 3β‐acetoxy‐urs‐12‐en‐28‐oyl chloride with phosphonodipeptides and their homologs. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:55–65, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20396     

Synthesis of n-(jasmonoyl)amino acid conjugates

Both racemic jasmonic acid [(±)-JA] and the naturally occurring (-)-enantiomer [(-)-JA] have been reacted with aliphatic, aromatic as well as acidic amino acids to form amide-linked derivatives. The diastereoigomeric products of (±)-jasmonic acid with S-Val, S-Leu, S-Ile, S-Phe, S-Trp, R-Val, and R-Phe could be separated by silica gel chromatography. The synthesized N-(jasmonoyl)-conjugates have been structurally characterized by MS, ¹H NMR, IR and ORD.     

Synthesis of oligoribonucleic acid conjugates using a cyclooctyne phosphoramidite

The conjugation of a ribonucleic acid 16-mer with the cationic amphiphilic peptide penetratin and an anionic hyaluronan tetrasaccharide by means of Cu-free "click" chemistry is reported. The alkyne-functionalized 16-mer was prepared by automated solid-phase synthesis, using a newly developed strained cyclooctyne phosphoramidite in the final coupling. Cycloaddition of the alkyne functionalized RNA to the azide containing biomolecules led to a clean conversion into the corresponding nucleic acid conjugates.     

Synthesis of protein-nucleic acid conjugates by expressed protein ligation

The synthesis of covalent conjugates of proteins and polyamide nucleic acids (PNA) is accomplished by expressed protein ligation of intein-fusion proteins and a PNA-cysteine conjugate.     

新型手性氨基酸烯砜的合成

以苯亚磺酸钠和3-氯-2-甲基-1丙烯为原料,经偶联、氯化、溴化,之后再与氨基酸胺化反应合成得到了两个新型手性氨基酸烯砜化合物。所获得化合物的结构经HR-MS,1H,13C和/或DEPT NMR验证。     

手性方酰化双取代哒嗪的合成及荧光性研究

哒嗪衍生物是一类重要的芳香杂环化合物,哒嗪环常出现于农药、医药等具有生物活性的化合物中,研究哒嗪化合物的结构和性能的关系具有重要的科学意义和潜在的应用价值.作为中心桥联基的有机液晶化合物我们已有过系列报道[1-4].     

Synthesis of nucleoside-amino acid conjugates containing boranephosphate, boranephosphorothioate and boranephosphoramidate linkages

Conjugates of 3^′-azido-2^′,3^′-dideoxythymidine (AZT) and 2^′,3^′-didehydro-2^′,3^′-dideoxythymidine (D4T) with the hydroxyl group of tyrosine containing boranephosphate and boranephosphorothioate moieties were prepared via the oxathiaphospholane and dithiaphospholane methodology as a mixture of P-diastereomers. Their structures were confirmed by MS analysis and ¹H, ³¹P NMR spectroscopy. It has been shown that the boranephosphorothioate linkage is unstable under acidic conditions. The first nucleoside-alanine conjugates connected through a boranephosphoramidate linkage were also obtained.     

Synthesis of chiral nonracemic 4-trans-substituted pipecolic acid derivatives

The syntheses and resolutions of enantiomerically enriched 4-phenyl, 4-tert-butyl, and 4-isopropyl pipecolic acids are described. Optically active diastereomers were prepared by diastereomeric salt formation with the chiral base, l-tyrosine hydrazide, to provide Cbz or Boc protected 4-cis-d-pipecolic acid derivatives in >98% ee. Subsequent esterification followed by sodium methoxide catalyzed epimerization provided the isomeric 4-trans-l-pipecolic esters. In addition, an efficient synthesis of 4-phenyl-cis-pipecolic acid is described.     

Synthesis of conjugates of glyco amino acids and glycopeptides with carboxylic acid hydrazides

It is proposed to use a hydrazine bridge for obtaining conjugates of glycopeptides with biologically active carboxylic acids. Diacylhydrazines have been synthesized from glucofuranosylglycoloyl-L-alanine and -butylmuramoyltripeptide.Simferopol' State University, 333036, Ukraine, Crimea, Simferopol', ul. Yaltinskaya, 4. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 731–734, September–October, 1997.