- A General Stereocontrolled Synthesis of Opines through Asymmetric Pd-Catalyzed N-Allylation of Amino Acid Esters
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A stereo-divergent synthesis of natural and unnatural opines in stereochemically pure form is based on the direct palladium-catalyzed N-allylation of α-amino acid esters (up to 97 % ee or 99 : 1 d.r.) using methyl (E)-2-penten-4-yl carbonate in the presence of only 1 mol% of a catalyst, prepared in-situ from the C2-symmetric diphosphine iPr-MediPhos and [Pd(allyl)Cl]2. Selected target compounds (incl. a derivative of the drug enalapril) were efficiently obtained from the N-allylated intermediates by oxidative cleavage (ozonolysis) of the allylic C=C bond under temporary N-Boc-protection.
- Albat, Dominik,Neud?rfl, J?rg-Martin,Schmalz, Hans-Günther
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p. 2099 - 2102
(2021/07/22)
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- Peptide Bond Formation of Amino Acids by Transient Masking with Silylating Reagents
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A one-pot peptide bond-forming reaction has been developed using unprotected amino acids and peptides. Two different silylating reagents, HSi[OCH(CF3)2]3 and MTBSTFA, are instrumental for the successful implementation of this approach, being used for the activation and transient masking of unprotected amino acids and peptides at C-termini and N-termini, respectively. Furthermore, CsF and imidazole are used as catalysts, activating HSi[OCH(CF3)2]3 and also accelerating chemoselective silylation. This method is versatile as it tolerates side chains that bear a range of functional groups, while providing up to >99% yields of corresponding peptides without any racemization or polymerization.
- Muramatsu, Wataru,Yamamoto, Hisashi
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supporting information
p. 6792 - 6797
(2021/05/29)
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- BROAD SPECTRUM ANTIBIOTICS
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Provided herein are antibacterial compounds, wherein the compounds in some embodiments have broad spectrum bioactivity. The compounds provided herein can in other embodiments overcome the resistance conferred by single amino acid mutations at defined posi
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- Dipeptide derivatives and antihypertensive drugs containing them
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There are disclosed dipeptide derivatives represented by the general formula: STR1 wherein R1 is a radical selected from the group consisting of alkyl, aralkyl and aryl groups optionally containing one or more substituent groups, R2 is a radical selected from the group consisting of hydrogen atoms and alkyl, aralkyl and aryl groups optionally containing one or more substituent groups, R3 is a radical selected from the group consisting of hydrogen atoms and alkyl, aralkyl and aryl groups optionally containing one or more substituent groups, R4 is a radical selected from the group consisting of hydrogen atoms and alkyl, aralkyl and aryl groups optionally containing one or more substituent groups, and R5 is a radical selected from the group consisting of hydroxyl, amino, hydroxyamino, alkyloxy, aralkyloxy, aryloxy, alkylamino, aralkylamino, arylamino, alkyloxyamino, aralkyloxyamino, aryloxyamino, acylamino and sulfonylamino groups, which alkyloxy, aralkyloxy and aryloxy groups optionally containing one or more substituent groups; wherein R3 may be combined with R2 or R4 to form an alkylene bridge optionally containing one or more oxygen atoms, sulfur atoms and nitrogen atoms and optionally containing one or more substituent groups. However, certain dipeptide derivatives within the above general formula are excluded from the invention. The dipeptide derivatives are useful for the treatment of hypertension.
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- Synthesis, Resolution, and Assignment of Configuration of Potent Hypotensive Retro-inverso Bradykinin Potentiating Peptide 5a(BPP5a) Analogues
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The effect on the the biological activity of an inverted amide group as an isosteric replacement for the Phe-Ala scissile bond of the BPP5a analogue 3>BPP5a has been studied.The synthesis of the retro-inverso pentapeptide 3,(R,S)-mAla4>BPP5a has been carried out in solution by coupling the pseudopeptide epimer HO-(R,S)-mAla-Pro-OBut to Glp-Lys(Boc)-gPhe-H.HCl, separation and identification of the resulting diastereomers 2(Boc),gPhe3,(S)-mAla4,Pro5-OBut>BPP5a and 2(Boc),gPhe3,(R)-mAla4,Pro5-OBut>BPP5a, and finally acidolytic cleavage. 3,(S)-mAla4>BPP5a, a moderate inhibitor of angiotensin converting enzyme (ACE) in vitro (I50=14 x 1E-5), was obtained and proved to be more potent than BPP5a as a hypotensive in normotensive rats without manifesting the bradykinin potentiating action of the natural peptide.
- Verdini, Antonio S.,Viscomi, Giuseppe C.
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p. 697 - 702
(2007/10/02)
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