203854-47-1Relevant articles and documents
Homologation of α-amino acids to β-amino acids: 9-Fluorenylmethyl chloroformate as a carboxyl group activating agent for the synthesis of Nα-protected aminoacyldiazomethanes
Kantharaju,Suresh Babu, Vommina V.
, p. 2152 - 2158 (2007/10/03)
An efficient and stereospecific homologation of urethane-protected α-amino acids to β-amino acids by Arndt-Eistert approach using an equimolar mixture of Fmoc-/Boc-/Z-α-amino acid and 9-fluorenylmethyl chloroformate for the acylation of diazomethane synth
Synthesis of Fmoc-/Boc-/Z-β-amino acids via Arndt-Eistert homologation of Fmoc-/Boc-/Z-α-amino acids employing BOP and PyBOP
Vasanthakumar,Babu, V. V. Suresh
, p. 1691 - 1695 (2007/10/03)
A simple and efficient protocol for Arndt-Eistert chain homologation of Fmoc-/Boc-/Z-α-amino acids using BOP or PyBOP as a coupling agent to the corresponding β-amino acids, synthesizing the key intermediate α-diazoketones as crystalline solids in good yield is described.
Synthesis of β-amino acids: 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyl-uronium tetrafluoroborate (TBTU) for activation of Fmoc-/Boc-/Z-α-amino acids
Patil, Basanagoud S.,Vasanthakumar, Ganga-Ramu,Suresh Babu
, p. 3089 - 3096 (2007/10/03)
A new and efficient method for the homologation of urethane protected α-amino acids to its β-homomers by the Arndt-Eistert method using TBTU as a coupling agent is described. Several Fmoc-/Boc-/Z-protected α-amino diazoketone derivatives have been obtaine
Homologation of α-amino acids to β-amino acids using Boc2O
Vasanthakumar, Ganga-Ramu,Patil, Basanagoud S.,Suresh Babu, Vommina V.
, p. 2087 - 2089 (2007/10/03)
The use of Boc2O as a coupling agent in the homologation of N-urethane protected-α-amino acid to its β-homomers by the Arndt-Eistert method is described. The homologation gives good yields without racemization. The use of Boc2O as a
Peptide folding induces high and selective affinity of a linear and small β-peptide to the human somatostatin receptor 4
Gademann,Kimmerlin,Hoyer,Seebach
, p. 2460 - 2468 (2007/10/03)
β-Peptides with side chains in the 2- and 3-positions on neighboring residues (of (S) configuration) are known to fold and form a turn (similar to an α-peptidic β-turn). Thus, we have synthesized an appropriately substituted β-tetrapeptide derivative to mimic the hormone somatostatin in its binding to the human receptors hsst1-5, which is known to rest upon a turn containing the amino acid residues Thr, Lys, Trp, and Phe. The N-acetyl-peptide amide Acβ3-HThr-β2-HLys-β3 -HTrp-β3-HPhe-NH2 (1) indeed shows all characteristics of the targeted turnmimic: Lys CH2 groups are in the shielding cone of the Trp indole ring (by NMR analysis, Figure 2) and there is high and specific nanomolar affinity for hsst4 receptor (Table 1). In contrast, the isomer 2 bearing the Lys side chain in 3-, rather than in the 2-position, has a 1000-fold smaller affinity to hsst4. The syntheses of the required Fmoc-protected β-amino acids (8-11, 17) are described (Schemes 1-3). Coupling of the β-amino acids was achieved by the manual solid-phase technique, on Rink resin.
Preparation of N-Fmoc-Protected β2- and β3-Amino Acids and Their Use as Building Blocks for the Solid-Phase Synthesis of β-Peptides
Guichard, Gilles,Abele, Stefan,Seebach, Dieter
, p. 187 - 206 (2007/10/03)
N-Fmoc-Protected (Fmoc = (9H-fluoren-9-ylmethoxy)carbonyl) β-amino acids are required for an efficient synthesis of β-oligopeptides on solid support. Enantiomerically pure Fmoc-β3-amino acids (β3: side chain and NH2 at C(3)(=C(β))) were prepared from Fmoc-protected (S)- and (R)-α-amino acids with aliphatic, aromatic, and functionalized side chains, using the standard or an optimized Arndt-Eistert reaction sequence. Fmoc-β2-Amino acids (β2 side chain at C(2), NH2 at C(3)(=C(β))) configuration bearing the side chain of Ala, Val, Leu, and Phe were synthesized via the Evans' chiral auxiliary methodology. The target β3-heptapeptides 5-8, a β3- pentadecapeptide 9 and a β2-heptapeptide 10 were synthesized on a manual solid-phase synthesis apparatus using conventional solid-phase peptide synthesis procedures (Scheme 3). In the case of β3-peptides, two methods were used to anchor the first β-amino acid: esterification of the ortho-chlorotrityl chloride resin with the first Fmoc-β-amino acid 2 (Method I, Scheme 2) or acylation of the 4-(benzyloxy)benzyl alcohol resin (Wang resin) with the ketene intermediates from the Wolff rearrangement of amino-acid-derived diazo ketone 1 (Method II, Scheme 2). The former technique provided better results, as exemplified by the synthesis of the heptapeptides 5 and 6 (Table 2). The intermediate from the Wolff rearrangement of diazo ketones 1 was also used for sequential peptide-bond formation on solid support (synthesis of the tetrapeptides 11 and 12). The CD spectra of the β2- and β3-peptides 5, 9. and 10 show the typical pattern previously assigned to an (M) 31 helical secondary structure (Fig.). The most intense CD absorption was observed with the pentadecapeptide 9 (strong broad negative Cotton effect at ca. 213 nm); compared to the analogous heptapeptide 5, this corresponds to a 2.5 fold increase in the molar ellipticity per residue!
