5673-89-2Relevant articles and documents
Phosphorus-Based Organocatalysis for the Dehydrative Cyclization of N-(2-Hydroxyethyl)amides into 2-Oxazolines
Soleymani Movahed, Farzaneh,Foo, Siong Wan,Mori, Shogo,Ogawa, Saeko,Saito, Susumu
, p. 243 - 257 (2021/12/17)
A metal-free, biomimetic catalytic protocol for the cyclization of N-(2-hydroxyethyl)amides to the corresponding 2-oxazolines (4,5-dihydrooxazoles), promoted by the 1,3,5,2,4,6-triazatriphosphorine (TAP)-derived organocatalyst tris(o-phenylenedioxy)cyclotriphosphazene (TAP-1) has been developed. This approach requires less precatalyst compared to the reported relevant systems, with respect to the phosphorus atom (the maximum turnover number (TON) ～30), and exhibits a broader substrate scope and higher functional-group tolerance, providing the functionalized 2-oxazolines with retention of the configuration at the C(4) stereogenic center of the 2-oxazolines. Widely accessible β-amino alcohols can be used in this approach, and the cyclization of N-(2-hydroxyethyl)amides provides the desired 2-oxazolines in up to 99% yield. The mechanism of the reaction was studied by monitoring the reaction using spectral and analytical methods, whereby an 18O-labeling experiment furnished valuable insights. The initial step involves a stoichiometric reaction between the substrate and TAP-1, which leads to the in situ generation of the catalyst, a catechol cyclic phosphate, as well as to a pyrocatechol phosphate and two possible active intermediates. The dehydrative cyclization was also successfully conducted on the gram scale.
Diboron-Catalyzed Dehydrative Amidation of Aromatic Carboxylic Acids with Amines
Sawant, Dinesh N.,Bagal, Dattatraya B.,Ogawa, Saeko,Selvam, Kaliyamoorthy,Saito, Susumu
supporting information, p. 4397 - 4400 (2018/08/09)
Tetrakis(dimethylamido)diboron and tetrahydroxydiboron are herein reported as new catalysts for the synthesis of aryl amides by catalytic condensation of aromatic carboxylic acids with amines. The developed protocol is both simple and highly efficient over a broad range of substrates. This method thus represents an attractive approach for the use of diboron catalysts in the synthesis of amides without having to resort to stoichiometric or additional dehydrating agents.
18F-Trifluoromethylation of Unmodified Peptides with 5-18F-(Trifluoromethyl)dibenzothiophenium Trifluoromethanesulfonate
Verhoog, Stefan,Kee, Choon Wee,Wang, Yanlan,Khotavivattana, Tanatorn,Wilson, Thomas C.,Kersemans, Veerle,Smart, Sean,Tredwell, Matthew,Davis, Benjamin G.,Gouverneur, Véronique
supporting information, p. 1572 - 1575 (2018/02/17)
The 18F-labeling of 5-(trifluoromethyl)-dibenzothiophenium trifluoromethanesulfonate, commonly referred to as the Umemoto reagent, has been accomplished applying a halogen exchange 18F-fluorination with 18F-fluoride, follo
Influence of chiral thiols on the diastereoselective synthesis of γ-lactams from cyclic anhydrides
Younai, Ashkaan,Fettinger, James C.,Shaw, Jared T.
scheme or table, p. 4320 - 4327 (2012/07/28)
The synthesis of γ-lactams from both four-component and imine-anhydride reactions is reported. The synthesis of 2-phenylcyclohexanethiol is described and this compound was evaluated along with an additional seven chiral thiols. A range of selectivity and yields was observed and comparisons to established reactions are made in order to account for the observed reactivity.
The use of phosphonium anhydrides for the synthesis of 2-oxazolines, 2-thiazolines and 2-dihydrooxazine under mild conditions
Petersson, Maria J.,Jenkins, Ian D.,Loughlin, Wendy A.
supporting information; experimental part, p. 739 - 746 (2009/06/20)
β-Hydroxy amides 6 and 7 were treated with triphenylphosphonium anhydride trifluoromethane sulfonate (3), or the cyclic analogue 4, to generate 2-oxazolines 5 and 8 under mild conditions. The reaction was optimised by examining the number of equivalents of reagents 3 or 4, or diisopropylethyl amine required to best effect cyclisation. The effects of altering the reaction temperature, reaction time, concentration, solvent, and addition rate also were investigated. However, it was found that use of a trityl group to block reaction at the hydroxyl or thiol group of the starting amides, and subsequent in situ detritylation, in the absence of base, led to greatly improved yields. Reagent 4 offered significant advantages in the purification of products and was used to dehydrate a range of trityl derivatives to form simple oxazolines, thiazolines, and a dihydro-1,3-oxazine, in high yield (85-99%), as well as a tetrahydro-1,3-oxazepine (31%).
Synthesis and photochemical properties of photo-cleavable crosslinkers
Omran, Ziad,Specht, Alexandre
supporting information; experimental part, p. 2434 - 2436 (2009/08/07)
We report herein the synthesis and the development of homo-bifunctional photo-cleavable sulfhydryl group cross-linkers that are able to react and then to photorelease two cysteines leading to the photoregulation of cross-linkers cleavage.
p-Hydroxyphenacyl bromide as photoremoveable thiol label: A potential phototrigger for thiol-containing biomolecules
Specht, Alexandre,Loudwig, Sandra,Peng, Ling,Goeldner, Maurice
, p. 8947 - 8950 (2007/10/03)
p-Hydroxyphenacyl bromide is described as a photoremovable thiol protecting group on three biomolecules containing a free thiol group. The protecting group is efficiently incorporated by chemical coupling to the biomolecule in an ethanol-buffer mixture. The photofragmentations (λ=312 nm) were analyzed by UV, HPLC and MS methods, yielding over 70% of the free biomolecules. The concomitant formation of p-hydroxyphenylacetic thioesters derived from the corresponding thiols, as a sulfur-containing side-product, should not hinder the use of this protecting group for the caging of thiol-containing biomolecules.
Methyl esters of N-protected-O-or -S-(4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2 - enopyranosyl)-L-serine, -L-threonine and -L-cysteine: Synthesis and some transformations
Liberek,Smiatacz
, p. 989 - 996 (2007/10/03)
Methyl esters of N-tosyl-O-(4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-enopyranosyl)-L-serine (5), -L-threonine (6) and N-benzoyl-5-(4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-enopyranosyl)-L -cysteine (7) have been synthesized by condensation of 3,4,6-tri-O-acetyl-1,5-anhydro-2-deoxy-D-arabino-hex-1-enitol (1) with respective derivatives of L-serine (2), L-threonine (3) and L-cysteine (4), cis-Hydroxylation and epoxydation of 2,3-unsaturated glycopyranoside 5 afforded O-glycosyl-L-serine derivatives with α-D-manno (8, 9), 2,3-anhydro-α-D-manno (10) and 2,3-anhydro-α-D-allo (11) structures, respectively. The structure of compounds as well as conformation of the sugar residue and configuration at the anomeric centre were established on the basis of the 1H and 13C NMR (DQF-COSY, TOCSY, HMBC), IR, MS (FD) spectrometric techniques and polarimetric data.
The synthesis and structure of the derivatives of 2-deoxy-2-hydroxyimino-D-lyxo-hexopyranosyl-L-cysteine and -thiophenol
Liberek, Beata,Konitz, Antoni,Frankowski, Ryszard,Smiatacz, Zygfryd
, p. 151 - 158 (2007/10/03)
3,4,6-Tri-O-acetyl-2-deoxy-2-hydroxyimino-β and -α-D-lyxo-hexopyranosides of thiophenol (3, 4) and the methyl ester of N-benzoyl-L-cysteine have been synthesised by condensation of 3,4,6-tri-O-acetyl-2-deoxy-2-nitroso-α-D-galactopyranosyl chloride with thiophenol and the L-cysteine derivative, respectively. The conformation of the sugar residue and configuration of the anomeric centre as well as of the hydroxyimino group were established on the basis of the 1H NMR (DQF-COSY, ROESY, TOCSY) spectrometric techniques and polarimetric data. Additionally, the structure of S-[3,4,6-tri-O-acetyl-2-deoxy-2-(Z)-hydroxyimino-β-D-lyxo-hexopyranosyl]-thiophenol (3) was supported by X-ray diffraction data. Copyright (C) 2000 Elsevier Science Ltd.
Highly Efficient Propane-1,3-dithiol Mediated Thiol-disulphide Interchange: a Facile and Clean Methodology for S-S Reduction in Peptides
Ranganathan, Subramania,Jayaraman, Narayanaswamy
, p. 934 - 936 (2007/10/02)
Propane-1,3-dithiol, at room temperature and in the absence of any promoter, neatly brings about the S-S -> 2SH change, and the latter can be isolated as acrylonitrile adducts; the methodology has been tested with several substrates including c-lysozyme, insulin and oxytocin, and spontaneous imidazole promoted S-deprotection was observed in the case of Z-Cys(S-CH2CH2CN)His-OMe.
