Synthesis Of Side Chain Research Articles

Water Permeability and Elastic Properties of an Archaea Inspired Lipid Synthesized by Click Chemistry

Author(s): Leriche, G; Manafirad, A; Nguyen, S; Bell, N; Patterson, JP; Thayumanavan, S; Yang, J; Dinsmore, AD; Gianneschi, NC | Abstract: Researchers report the synthesis of a new archaea-inspired tetraether lipid and study the mechanical elastic properties of membranes made from this bolalipid. To access structural diversity in the hydrophobic moiety of the lipids and to tune membrane properties, they have used used Huisgen 1,3-dipolar cycloaddition strategy to design and synthesize a tetraether lipid incorporating phytanyl side chains and polar 1,4 triazole rings known to change lipid packing. The researchers demonstrate the first example of the synthesis of phytanyl side chain incorporated tetraether lipids with 1,4-triazole rings. They also confirm the ability of lipids incorporating 1,4-triazole rings to form stable small and giant vesicles and examined their physical and mechanical properties using a micropipette aspiration technique.

Synthesis of Side-Chain Locked Analogs of 1α,25-Dihydroxyvitamin D3 Bearing a C17 Methyl Group.

A convergent synthesis of side-chain locked vitamin D analogs 3 and 4, which bind strongly in silico to the vitamin D receptor (VDR), is described. The synthetic approach features an SN2'- syn displacement of carbamates by cuprates to set the challenging quaternary stereogenic center at C17 and a Pd-catalyzed construction of the triene system in the presence of a diyne moiety.

A convenient one-pot approach to Paclitaxel (Taxol) side chain via 1,3-dipolar cycloaddition of carbonyl ylides and N-benzoylbenzyl imines

An efficient cascade approach to α-hydroxy-β-amino acid derivatives is reported, which goes through a 1,3-dipolar cycloaddition of carbonyl ylides and N-benzoylbenzyl imines and followed by hydrolysis under acidic conditions. This is the first example of using N-benzoylbenzyl imine as dipolarophile for 1,3-dipolar cycloaddition with carbonyl ylide, which provides a direct and convenient access for the one-pot synthesis of paclitaxel side chain and its derivatives.

Thermal and mechanical properties of tailor-made unbranched α-1,3-glucan esters with various carboxylic acid chain length

The convenient and environmentally friendly method for in vitro polymerization catalyzed by glucosyltransferase, designated as GtfJ, extracted from recombinant E. Coli was used to synthesize tailor-made α-1,3-glucan (α-1,3-d-glucan) having moderate molecular weight (Mw=2.0×105) and no branches. With the aim to improve thermoplasticity of this polysaccharide, after in vitro synthesis, chemical modification by acylation was selected and then fully substituted α-1,3-glucan esters were successfully obtained via both homogeneous and heterogeneous methods. Thermal degradation temperature of α-1,3-glucan esters was improved after esterification and dependent on neither side chain length nor synthesis methods. DSC curves suggested a presence of crystal structure in α-1,3-glucan acetate, propionate, butyrate, valerate and hexanoate due to detectable melting endotherm, whereas octanoate exhibited amorphous behavior. Tm’s of α-1,3-glucan esters were relatively high, more than 200°C, in comparison with commercial plastics. The shorter chain length of acid component, the higher Tm and Tg ester products exhibited. In addition, tensile strength of α-1,3-glucan esters decreased in contrast with elongation at break with an increase in alkyl chain length of an acid component. Thus, crystalline and amorphous α-1,3-glucan esters with adjustable thermal and mechanical properties obtained from this research are promising materials for continuing applied researches and contemplating the future application in bio-based thermoplastic materials.

Synthesis of Side-Chain Functionalized Polynorbornene Supported Half-Metallocene Catalysts and Their Application in Ethylene Polymerization.

Synthesis of Side-Chain Functionalized Polynorbornene Supported Half-Metallocene Catalysts and Their Application in Ethylene Polymerization.

Enzymatic synthesis of an ezetimibe intermediate using carbonyl reductase coupled with glucose dehydrogenase in an aqueous-organic solvent system

(4S)-3-[(5S)-5-(4-Fluorophenyl)-5-hydroxypentanoyl]-4-phenyl-1,3-oxazolidin-2-one ((S)-ET-5) is an important chiral intermediate in the synthesis of chiral side chain of ezetimibe. Recombinant Escherichia coli expressing carbonyl reductase (CBR) was successfully constructed in this study. The total E. coli biomass and the specific activity of recombinant CBR in 5L fermenter culture were 10.9gDCWL−1 and 14900.3Ug−1DCW, respectively. The dual-enzyme coupled biocatalytic process in an aqueous-organic biphasic solvent system was first constructed using p-xylene as the optimal organic phase under optimized reaction conditions, and 150gL−1 (4S)-3-[5-(4-fluorophenyl)-1,5-dioxophentyl]-4-phenyl-1,3-oxazolidin-2-one (ET-4) was successfully converted to (S)-ET-5 with a conversion of 99.1% and diastereomeric excess of 99% after 24-h, which are the highest values reported to date for the production of (S)-ET-5.

Synthesis of Side-Chain Modified Peptides Using Iterative Solid Phase ‘Click' Methodology

A series of side-chain modified peptides have been prepared via an iterative sequence of peptide couplings and azide–alkyne cycloadditions (‘click’ reactions) using Fmoc-solid phase peptide synthesis. This efficient modular synthetic route allows the systematic and sequential incorporation of a variety of side-chain modifications onto short peptides. The versatility of this approach was demonstrated by the synthesis of a series of short peptides with appended anion recognition motifs and fluorescent indicators.

Preparation of an N-sec-alkyl 2,6-disubstituted aniline: a key intermediate in the divergent synthesis of S-Metolachlor metabolites

A simple method to prepare a 2,6-disubstituted aniline containing a N-sec-alkyl group and a carbonyl on one ortho substituent is reported. This method was used to accomplish the first synthesis of side chain oxidized ethylsulfonic acid (ESA) and oxanilic acid (OXA) metabolites of S-Metolachlor (S-Moc) herbicide. The 2,6-disubstituted aniline functionality was installed by a Sugasawa reaction of readily available ortho-toluidine. The N-sec alkyl group was introduced by a Mitsunobu alkylation of the nosyl-activated 2-acetyl-6-methyl-substituted aniline. This crucial step enabled access to the key 2,6-disubstituted aniline intermediate which was used in the divergent synthesis of S-Moc metabolites. A bioinspired synthesis of the keto-ESA metabolite was achieved in one step from the hydroxyl-ESA metabolite using a ruthenium-catalyzed oxidation. [Display omitted]

A breakthrough in enzyme technology to fight penicillin resistance-industrial application of penicillin amidase.

Enzymatic penicillin hydrolysis by penicillin amidase (also penicillin acylase, PA) represents a Landmark: the first industrially and economically highly important process using an immobilized biocatalyst. Resistance of infective bacteria to antibiotics had become a major topic of research and industrial activities. Solutions to this problem, the antibiotics resistance of infective microorganisms, required the search for new antibiotics, but also the development of derivatives, notably penicillin derivatives, that overcame resistance. An obvious route was to hydrolyse penicillin to 6-aminopenicillanic acid (6-APA), as a first step, for the introduction via chemical synthesis of various different side chains. Hydrolysis via chemical reaction sequences was tedious requiring large amounts of toxic chemicals, and they were cost intensive. Enzymatic hydrolysis using penicillin amidase represented a much more elegant route. The basis for such a solution was the development of techniques for enzyme immobilization, a highly difficult task with respect to industrial application. Two pioneer groups started to develop solutions to this problem in the late 1960s and 1970s: that of Günter Schmidt-Kastner at Bayer AG (Germany) and that of Malcolm Lilly of Imperial College London. Here, one example of this development, that at Bayer, will be presented in more detail since it illustrates well the achievement of a solution to the problems of industrial application of enzymatic processes, notably development of an immobilization method for penicillin amidase suitable for scale up to application in industrial reactors under economic conditions. A range of bottlenecks and technical problems of large-scale application had to be overcome. Data giving an inside view of this pioneer achievement in the early phase of the new field of biocatalysis are presented. The development finally resulted in a highly innovative and commercially important enzymatic process to produce 6-APA that created a new antibiotics industry and that opened the way for the establishment of over 100 industrial processes with immobilized biocatalysts worldwide today.

ChemInform Abstract: Synthesis of Side Chain N,N′‐Diaminoalkylated Derivatives of Basic Amino Acids for Application in Solid‐Phase Peptide Synthesis

AbstractReview: 65 refs.

UDP-arabinopyranose mutase 3 is required for pollen wall morphogenesis in rice (Oryza sativa).

l-Arabinose is one of the main constituents of cell wall polysaccharides such as pectic rhamnogalacturonan I (RG-I), glucuronoarabinoxylans and other glycoproteins. It is found predominantly in the furanose form rather than in the thermodynamically more stable pyranose form. UDP-L-arabinofuranose (UDP-Araf), rather than UDP-L-arabinopyranose (UDP-Arap), is a sugar donor for the biosynthesis of arabinofuranosyl (Araf) residues. UDP-arabinopyranose mutases (UAMs) have been shown to interconvert UDP-Araf and UDP-Arap and are involved in the biosynthesis of polysaccharides including Araf. The UAM gene family has three members in Oryza sativa. Co-expression network in silico analysis showed that OsUAM3 expression was independent from OsUAM1 and OsUAM2 co-expression networks. OsUAM1 and OsUAM2 were expressed ubiquitously throughout plant development, but OsUAM3 was expressed primarily in reproductive tissue, particularly at the pollen cell wall formation developmental stage. OsUAM3 co-expression networks include pectin catabolic enzymes. To determine the function of OsUAMs in reproductive tissues, we analyzed RNA interference (RNAi)-knockdown transformants (OsUAM3-KD) specific for OsUAM3. OsUAM3-KD plants grew normally and showed abnormal phenotypes in reproductive tissues, especially in terms of the pollen cell wall and exine. In addition, we examined modifications of cell wall polysaccharides at the cellular level using antibodies against polysaccharides including Araf. Immunolocalization of arabinan using the LM6 antibody showed low levels of arabinan in OsUAM3-KD pollen grains. Our results suggest that the function of OsUAM3 is important for synthesis of arabinan side chains of RG-I and is required for reproductive developmental processes, especially the formation of the cell wall in pollen.

Tocopherol side chain synthesis via asymmetric organocatalytic transfer hydrogenation and convenient measurement of stereoselectivity

An asymmetric synthetic route for 1-iodofarnesane, a key intermediate for tocopherol side chain synthesis, starting from (+)-(R)-citronellal was developed. 1-Iodofarnesane was prepared through eight steps in about 50% overall yield, and asymmetric transfer hydrogenation of the enal with a chiral organocatalyst was conducted as a stereoinduction step. To measure the stereoinduction level and optical purity of the product, a convenient analytical method was developed in which a phenylcarbamate derivative of the C15 alcohol was found to be suitable to give proper polarity and UV-activity for chiral UV-HPLC analysis.

Expanding the clinical spectrum of B4GALT7 deficiency: homozygous p.R270C mutation with founder effect causes Larsen of Reunion Island syndrome.

First described as a variant of Larsen syndrome in Reunion Island (LRS) in the southern Indian Ocean, 'Larsen of Reunion Island syndrome' is characterized by dwarfism, hyperlaxity, multiple dislocations and distinctive facial features. It overlaps with Desbuquois dysplasia, Larsen syndrome and spondyloepiphyseal dysplasia with dislocations ascribed to CANT1, FLNB and CHST3 mutations, respectively. We collected the samples of 22 LRS cases. After exclusion of CANT1, FLNB and CHST3 genes, an exome sequencing was performed in two affected second cousins and one unaffected sister. We identified a homozygous missense mutation in B4GALT7, NM_007255.2: c.808C>T p.(Arg270Cys) named p.R270C, in the two affected cases, not present in the unaffected sister. The same homozygous mutation was subsequently identified in the remaining 20 LRS cases. Our findings demonstrate that B4GALT7 is the causative gene for LRS. The identification of a unique homozygous mutation argues in favor of a founder effect. B4GALT7 encodes a galactosyltransferase, required for the initiation of glycoaminoglycan side chain synthesis of proteoglycans. This study expands the phenotypic spectrum of B4GALT7 mutations, initially described as responsible for the progeroid variant of Ehlers-Danlos syndrome. It further supports a common physiopathological basis involving proteoglycan synthesis in skeletal disorders with dislocations.

Synthesis and evaluation of amide side-chain modified Agomelatine analogues as potential antidepressant-like agents

In this work, nineteen analogues of Agomelatine were readily synthesized through structural modification of the acetamide side-chain starting from the key common intermediate 2-(7-methoxynaphthalen-1-yl) ethanamine (3), which was prepared from commercially available compound 2-(7-methoxynaphthalen-1-yl) acetonitrile (2) in two steps. Corticosterone-induced PC12 pheochromocytoma cells phenotypic in vitro model was utilized to evaluate their potential antidepression activities. Imide compound 4a and acylamino carboxylic acid analogue 5b showed good protective effects on traumatic PC12 cells with protection rates of 34.2% and 23.2%, respectively. Further in vivo assessments in C57 mice FST (forced swim test) model demonstrated that compound 4a significantly reduced the immobility time of the tested subjects, indicating antidepressant-like activity. Preliminary toxicity assays conducted on human normal liver L02 cells and embryonic kidney 293 cells suggested a relatively low safety risk for compound 4a compared with the marketed drugs Agomelatine and Fluoxetine. The promising antidepressant-like efficacy of compound 4a, together with the relatively low toxicity to the normal tested cells and high liability of diffusion through the blood–brain barrier (BBB), presents us insights of exploration of me-better drug candidates of Agomelatine.

Synthesis of ester side chain functionalized all-conjugated diblock copolythiophenes via the Rieke method

Ester-functionalized all-conjugated diblock copolythiophenes are synthesized by an optimized Rieke zinc protocol. These light-harvesting semiconducting electron donor polymers are of high interest in the field of organic photovoltaics as both the block architecture and the (functionalized) side chains play a crucial role in determining the bulk heterojunction active layer blend (nano)morphology and thereby the final polymer solar cell efficiency and lifetime.

Effects of sesamin on the biosynthesis of chondroitin sulfate proteoglycans in human articular chondrocytes in primary culture

Osteoarthritis (OA) is a degenerative joint disease that progressively causes a loss of joint functions and the impaired quality of life. The most significant event in OA is a high degree of degradation of articular cartilage accompanied by the loss of chondroitin sulfate-proteoglycans (CS-PGs). Recently, the chondroprotective effects of sesamin, the naturally occurring substance found in sesame seeds, have been proved in a rat model of papain-induced osteoarthritis. We hypothesized that sesamin may be associated with possible promotion of the biosynthesis of CS-PGs in human articular chondrocytes. The aim of the study was to investigate the effects of sesamin on the major CS-PG biosynthesis in primary human chondrocyte. The effects of sesamin on the gene expression of the PG core and the CS biosynthetic enzymes as well as on the secretion of glycosaminoglycans (GAGs) in monolayer and pellet culture systems of articular chondrocytes. Sesamin significantly increased the GAGs content both in culture medium and pellet matrix. Real-time-quantitative PCR showed that sesamin promoted the expression of the genes encoding the core protein (ACAN) of the major CS-PG aggrecan and the biosynthetic enzymes (XYLT1, XYLT2, CHSY1 and CHPF) required for the synthesis of CS-GAG side chains. Safranin-O staining of sesamin treated chondrocyte pellet section confirmed the high degree of GAG accumulation. These results were correlated with an increased level of secreted GAGs in the media of cultured articular chondrocytes in both culture systems. Thus, sesamin would provide a potential therapeutic strategy for treating OA patients.

Synthesis of three OSW-1 analogs with maltose side chains bearing different protection groups

In order to simplify the synthesis of OSW-1's disaccharide side chain and explore the structure–activity relationship of OSW-1, three 16α-O-maltose OSW-1 analogs carrying three maltose side chains bearing different protections were designed and synthesized.

Enantiospecific synthesis of methyl ester side chain of bishomoharringtonine

The enantiospecific total synthesis of methyl ester derivative of bishomoharringtonine side chain is accomplished from l-glutamate in 41 % overall yield. Key feature of the synthesis is the construction of the chiral quaternary center by a Wittig reaction to obtain single configuration trisubstitutes olefin and the subsequent complete chirality transfer of [2, 3]-Meisenheimer rearrangement.

Enantioselective Total Synthesis of Pladienolide B: A Potent Spliceosome Inhibitor

An enantioselective and convergent total synthesis of pladienolide B (1) is described. Pladienolide B binds to the SF3b complex of a spliceosome and inhibits mRNA splicing activity. The synthesis features an epoxide opening reaction, an asymmetric reduction of a β-keto ester, and a cross metathesis strategy for the side chain synthesis.

Design, synthesis and biological evaluation of simplified side chains of the macrolide antibiotic etnangien

Novel simplified side chains of the potent RNA polymerase inhibitor etnangien were designed, synthesized and evaluated for antibacterial activity against Gram-positive bacteria and one Gram-negative bacterium.