• synthesis
  • The present invention is directed to synthase enzymes relevant to fatty acid synthesis in plants, protein preparations, amino acid and nucleic acid sequences related thereto, and methods of use for such compositions. (google.com)
  • The current production method is based on the first scalable synthesis developed by Gilead Sciences starting from naturally occurring quinic acid or shikimic acid. (wikipedia.org)
  • A reported azide-free Roche synthesis of tamiflu is summarised graphically below: The synthesis commences from naturally available (−)-shikimic acid. (wikipedia.org)
  • A recent patent claims the synthesis of 4-phenylbutanoic acid via a Friedel-Crafts acylation of benzene and γ-butyrolactone with aluminum chloride at 60 °C followed by a work up with dilute sodium hydroxide solution and subsequent acidification in 94% crude yield and 81% pure yield. (wikipedia.org)
  • to allow the synthesis of substituated oxazoles from readily available amino acid derivatives. (wikipedia.org)
  • In organic chemistry, peptide synthesis is the production of peptides, which are organic compounds in which multiple amino acids are linked via amide bonds, also known as peptide bonds. (wikipedia.org)
  • Chemical synthesis facilitates the production of peptides which are difficult to express in bacteria, the incorporation of unnatural amino acids, peptide/protein backbone modification, and the synthesis of D-proteins, which consist of D-amino acids. (wikipedia.org)
  • Pioneered by Robert Bruce Merrifield, SPPS caused a paradigm shift within the peptide synthesis community, and allows the rapid assembly of a peptide chain through successive reactions of amino acids onto an insoluble porous support. (wikipedia.org)
  • The peptide remains covalently attached to the support throughout the synthesis, allowing it to be easily isolated from reagents and reaction by-products after each step via simple filtration and washing of the polymer beads with the reaction solvent (usually DMF or NMP). (wikipedia.org)
  • soluble
  • Substituted borate and carborate anions having unusual properties of being exceptionally weakly nucleophilic and being soluble in non-polar solvents. (google.com)
  • of an additive combination consisting essentially of from 1 to 5 parts by weight of an amine derivative of thio-bis-(C 12 to C 50 alkyl lactone carboxylic acid) and from 1 to 100 parts by weight of an oil-soluble amorphous hydrocarbon having less than about 5 wt. (google.com)
  • methyl
  • 1,12-Dimethyl-1,12-dicarba-closo-dodecaborane was permethylated via a methyl triflate - triflic acid mixture and 1,12-dicarba-closo-dodecaborane was methylated at all 10 boron vertices in an analogous reaction (Jiang, W. et at. (google.com)
  • reaction
  • The reaction for preparing these novel acyl-derivatives takes place normally at a temperature between 0 C. and 80 C. under anhydrous conditions and in the presence of an excess of trifluoroacetic acid. (google.com)
  • This acid chloride ketal is used in the reaction with β-hydroxy γ-butyrobetaine (carnitine) in accordance with the previously mentioned procedures. (google.com)
  • A significant side reaction that occurs under these conditions is the diazo transfer reaction: instead of fragmenting into an azide and sulfinic acid, the intermediate triazene salt may break down to a diazo compound and sulfonamide. (wikipedia.org)
  • Butadiene 1 reacts in an asymmetric Diels-Alder reaction with the esterification product of acrylic acid and 2,2,2-trifluoroethanol 2 catalysed by the CBS catalyst. (wikipedia.org)
  • In the Pfitzinger reaction of 1-tetralone with isatin, a compound called tetrofan (3,4-dihydro-1,2-benzacridine-5-carboxylic acid) is formed. (wikipedia.org)
  • This avoids unwanted reaction at those groups during the peptide coupling step, which occurs between the peptide N-terminal amine and the C-terminal carboxylate of the amino acid to be coupled. (wikipedia.org)
  • SPPS is limited by reaction yields, and typically peptides and proteins in the range of 70 amino acids are pushing the limits of synthetic accessibility. (wikipedia.org)
  • The silyl-Hilbert-Johnson (or Vorbrüggen) reaction, which employs silylated heterocyclic bases and electrophilic sugar derivatives in the presence of a Lewis acid, is the most common method for forming nucleosides in this manner. (wikipedia.org)
  • 2) The silyl-Hilbert-Johnson (SHJ) reaction (or Vorbrüggen reaction), the mildest general method for the formation of nucleosides, is the combination of a silylated heterocycle and protected sugar acetate in the presence of a Lewis acid. (wikipedia.org)
  • amine
  • Using the inexpensive Lewis acid magnesium bromide diethyl etherate (commonly prepared fresh by the addition of magnesium turnings to 1,2-dibromoethane in benzene:diethyl ether), the epoxide is opened with allyl amine to yield the corresponding 1,2-amino alcohol. (wikipedia.org)
  • The free N-terminal amine of the peptide is coupled to a single N-protected amino acid unit. (wikipedia.org)
  • The N-terminal protecting group is removed in the subsequent step, revealing a new N-terminal amine onto which a further amino acid may be attached. (wikipedia.org)
  • Despite being thermodynamically favorable, direct amide bond formation between an amine and carboxylic acid suffers from a high activation energy, and as such often requires high temperatures. (wikipedia.org)
  • mixture
  • It relies on pumps to pass a pressurized liquid solvent containing the sample mixture through a column filled with a solid adsorbent material. (wikipedia.org)
  • A sample is dissolved in a solvent mixture of Toluene/ Propan-2-ol with 0.5% deionised water. (wikipedia.org)
  • amino acid
  • Each amino acid to be coupled to the peptide chain N-terminus must be protected on its N-terminus and side chain using appropriate protecting groups such as Boc (acid-labile) or Fmoc (base-labile), depending on the side chain and the protection strategy used (see below). (wikipedia.org)
  • Thus highly optimized amide bond formation conditions are required, employing highly efficient coupling reagents and adding an excess of each amino acid (between 2- and 10-fold). (wikipedia.org)
  • The minimization of amino acid racemization during coupling is also of vital importance to avoid epimerization in the final peptide product. (wikipedia.org)
  • reacts
  • Mid-FTIR spectroscopy can be used to rapidly and quantitatively determine the TBN of hydrocarbon lubricating oils by spectroscopically measuring the carboxylate (COO-) functional group of the salt produced when trifluoroacetic acid (TFA) reacts with basic constituents present in an oil sample. (wikipedia.org)
  • Lewis
  • 4-Phenylbutanoic acid can also be quantitatively converted into 1-tetralone by heating to 180 °C and addition of catalytic amounts of strong Lewis acids such as bismuth(III)bis(trifluoromethanesulfonyl)amide [Bi(NTf2) which is relatively easily accessible. (wikipedia.org)
  • The combination of aluminum chloride as the Friedel-Craft Lewis acid and trifluoromethanesulfonic acid as the Robinson-Gabriel cyclodehydrating agent were determined to generate the desired products. (wikipedia.org)
  • The second category of acids are Lewis acids, which form a covalent bond with an electron pair. (wikipedia.org)
  • Lewis considered this as a generalization of the Brønsted definition, so that an acid is a chemical species that accepts electron pairs either directly or by releasing protons (H+) into the solution, which then accept electron pairs. (wikipedia.org)
  • Conversely, many Lewis acids are not Arrhenius or Brønsted-Lowry acids. (wikipedia.org)
  • In modern terminology, an acid is implicitly a Brønsted acid and not a Lewis acid, since chemists almost always refer to a Lewis acid explicitly as a Lewis acid. (wikipedia.org)
  • Interestingly, although alcohols and amines can be Brønsted-Lowry acids, they can also function as Lewis bases due to the lone pairs of electrons on their oxygen and nitrogen atoms. (wikipedia.org)
  • Depending on the nature of the Lewis acid used, coordination of the nucleophile to the Lewis acid may be significant. (wikipedia.org)
  • it is much more important when a stronger Lewis acid like tin(IV) chloride is employed. (wikipedia.org)
  • sulfonic acid
  • A novel fluorinated cation exchange membrane containing carboxylic acid groups and sulfonic acid groups, both in the form of a specific pendant structure, the carboxylic acid groups being at least 20% on one surface of the membrane and gradually decreasing toward the innerside of the membrane, which. (google.com)
  • This invention relates to a novel fluorinated cation exchange membrane having both carboxylic acid groups and sulfonic acid groups, intermediates and starting materials for production thereof and also to processes for producing such materials. (google.com)
  • This invention also concerns a novel fluorinated cation exchange membrane having sulfonic acid groups with a high ion-exchange capacity and being provided with physically high strength. (google.com)
  • The solution is then titrated with Trifluoro methane sulfonic acid (TFMSA) to a single thermometric endpoint. (wikipedia.org)
  • reactions
  • In general, for reactions of enolates substituted with Evans oxazolidinones, trifluoroacetic acid promotes diazo transfer while acetic acid encourages azidation (the reasons why are unclear). (wikipedia.org)
  • In the context of acid-base reactions, the abbreviation HAc is sometimes used, where Ac in this case is a symbol for acetate (rather than acetyl). (wikipedia.org)
  • Modern definitions are concerned with the fundamental chemical reactions common to all acids. (wikipedia.org)
  • unless otherwise specified, acid-base reactions are assumed to involve the transfer of a proton (H+) from an acid to a base. (wikipedia.org)
  • catalytic hydrogenation
  • Roche has other routes to oseltamivir that do not involve the use of (−)-shikimic acid as a chiral pool starting material, such as a Diels-Alder route involving furan and ethyl acrylate or an isophthalic acid route, which involves catalytic hydrogenation and enzymatic desymmetrization. (wikipedia.org)
  • unnatural
  • In addition to the conventional proteogenic amino acids, we can incorporate special forms of these residues such as α- or β-homo amino acids or D-form residues, as well as unnatural residues such as citrulline or pyroglutamine. (covalab.com)
  • benzene
  • C6H5I + CH3CO3H + CH3CO2H → C6H5I(O2CCH3)2 + H2O Phenyliodine bis(trifluoroacetate), PIFA, or (bis(trifluoroacetoxy)iodo)benzene is a related compound based on trifluoroacetic acid. (wikipedia.org)
  • methanesulfonic
  • With the librated methanesulfonic acid, the aziridine opens cleanly to yield a diamine that immediately undergoes a second transimination. (wikipedia.org)
  • The acid-catalyzed cyclization can also be carried out with methanesulfonic acid. (wikipedia.org)
  • yields
  • Due to lower yields and the extra steps required (because of the additional dehydration), the quinic acid route was dropped in favour of the one based on shikimic acid, which received further improvements by Hoffmann-La Roche. (wikipedia.org)
  • polar
  • The used oil method uses a less polar solvent and weaker titrant, which will not dissolve the wear metals produced during operation, hence it is more suitable to analyse used oils. (wikipedia.org)
  • synthetic
  • Due to its limited supply, searches for alternative synthetic routes preferably not requiring shikimic acid are underway and to date several such routes have been published. (wikipedia.org)
  • salt
  • 15. A compound according to claim 1, wherein said compound is: 1-(3-(4-amidinophenyl)-2-oxo-5-oxazolidinylmethyl)piperidine-4-carboxylic acid or salt thereof. (google.com.au)
  • common
  • An oil formulation contains basic additives, designed to react with and neutralise acids , preventing damage to engine parts, including corrosion of metal surfaces and damage to Although, IP Standard test methods exist the more common methods for TBN are ASTM standardised, such as the potentiometric titration for fresh oils (Test method TBN ASTM D2896). (wikipedia.org)
  • combination
  • The combination of trifluoroacetic acid (TFA), trimethylsilyl chloride (TMSCl), and hexamethyldisilazide (HMDS) generates trimethylsilyl trifluoroacetate in situ, which accomplishes both the silylation of the heterocycle and its subsequent coupling with the sugar. (wikipedia.org)