Stereocontrolled [11C]Alkylation of N-Terminal Glycine Schiff Bases To Obtain Dipeptides
The use of various quaternary ammonium salts as chiral phase-transfer catalysts allowed effective and stereoselective radiochemical [11C]alkylation to obtain functionalized dipeptides. We herein report a broadly applicable procedure for the asymmetric [11C]alkylation of dipeptides to give labeled N-terminal peptides by using different [11C]alkyl halides. Contended stereoselectivities of the reactions were observed by using 11C-labeled alkyl halides, [11C]methyl iodide and [11C]benzyl iodide, and diastereomeric ratios with different specialized catalysts of 95:5 and 90:10 were achieved, respectively. Accordingly, the straightforward synthesis of enantioenriched compounds should play a vital role in peptide-based radiopharmaceutical development and positron emission tomography imaging.
Filp, Ulrike,Peko?ak, Aleksandra,Poot, Alex J.,Windhorst, Albert D.
supporting information
p. 5592 - 5596
(2017/10/13)
Amide formation in one pot from carboxylic acids and amines via carboxyl and sulfinyl mixed anhydrides
An efficient method has been developed for the preparation of yet unknown acyclic mixed anhydrides of carboxylic and sulfinic acids. Sterically hindered 2-methylbut-3-ene-2-sulfinyl carboxylates add primary and secondary amines preferentially onto the carbonyl moieties realizing a new method for the one-pot preparation of carboxamides. It uses 1:1 mixtures of carboxylic acids and amines without a base, requires no excess of reagents, and liberates only volatile coproducts. Protected di- and tripeptides have been prepared in solution without epimerization by application of this method.
Zambron, Bartosz K.,Dubbaka, Srinivas R.,Markovic, Dean,Moreno-Clavijo, Elena,Vogel, Pierre
supporting information
p. 2550 - 2553
(2013/07/05)
Design, synthesis and crystallographic analysis of nitrile-based broad-spectrum peptidomimetic inhibitors for coronavirus 3C-like proteases
Coronaviral infection is associated with up to 5% of respiratory tract diseases. The 3C-like protease (3CLpro) of coronaviruses is required for proteolytic processing of polyproteins and viral replication, and is a promising target for the deve
Total synthesis and determination of the absolute configuration of guadinomines B and C2
This article describes the determination of the absolute configurations of the guadinomines, which are novel cyclic guanidyl natural products that are inhibitors of the type III secretion system (TTSS) of bacteria. Any compound that interrupts the TTSS of bacteria is potentially an ideal anti-infectious drug. The reliable asymmetric synthesis of guadinomines has revealed their absolute configurations, which could not have been defined without this synthetic approach. Our report not only describes the asymmetric total synthesis of the title compounds, but also demonstrates the novel concise synthesis of tri-substituted piperazinone cores as optically pure forms. The novel feature of our method is an intramolecular SN2 cyclization that uses PPh 3 and I2 to construct the unique 5membered cyclic guanidine substructure.
There are disclosed active fragments of vasoactive peptides and methods of preparation. The active fragments comprise the following amino acid sequences: (a) X-MET-ALA-VAL-X1 (b) X-MET-ALA-VAL-LYS-X1 (c) X-MET-ALA-VAL-LYS
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(2008/06/13)
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