Helical <scp>l</scp>–Leu‐Based Peptides Having Chiral Five‐Membered Carbocyclic Ring Amino Acids with an Ethylene Acetal Moiety

Koba, Yurie; Ueda, Atsushi; Oba, Makoto; Doi, Mitsunobu; Demizu, Yosuke; Kurihara, Masaaki; Tanaka, Masakazu

doi:10.1002/slct.201700832

Cited by 5 publications

(3 citation statements)

References 38 publications

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“… Homopeptides consisting of Ac 5 c-based chiral dAAs, Ac 5 c dOM having two chiral centers in the side chain, form helical structures with a preference for right-handed ( P ) or left-handed ( M ) helical screw directions due to the chiral centers . We recently designed and synthesized a cyclic dAA Ac 5 c 3EG , in which the α-carbon atom was a chiral center . The acetal moiety at the γ-position was changeable, and its bulkiness and hydrogen-bonding donors were considered to affect the helical screw direction of the peptides.…”

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confidence: 88%

“…However, the intensities of these spectra were too low to form a complete left-handed ( M ) helical structure. These results were similar to a previous report on ( S )-Ac 5 c 3EG homopeptides, and thus the helical screw-sense bias by the α-chiral center of the Boc-protected ( S )-(−)-cucurbitine was weak. To gain further insights into the preferred secondary structures in solution, detailed 1 H NMR spectral measurements of heptapeptide 14 were performed.…”

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confidence: 99%

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Synthesis of (S)-(−)-Cucurbitine and Conformation of Its Homopeptides

et al. 2021

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A chiral cyclic α,α-disubstituted α-amino acid, (S)-(−)-cucurbitine, which has a pyrrolidine ring with a chiral center at the α-position, was synthesized, and its homopeptides were prepared. (S)-(−)-Cucurbitine homopeptides with a Boc-protecting group formed helical structures with slight control of the helical screw sense to the left-handed form. The state of the pyrrolidine ring in (S)-(−)-cucurbitine was important for the control of the helical structures and helical screw sense of its homopeptides.

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confidence: 88%

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confidence: 99%

Synthesis of (S)-(−)-Cucurbitine and Conformation of Its Homopeptides

et al. 2021

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“…From this point of view, the introduction of allyl tethered cis -4-hydroxy- l -proline or ( R )-α-allyl-proline can be suitable for this purpose. Secondary structures, as well as helical screw directions, can be controlled by introducing 1-aminocycloalkane-1-carboxylic acid in homopeptides [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ] and heteropeptides [ 41 , 42 , 43 ], and these constrained peptides catalyze asymmetric 1,4-addition reactions [ 44 , 45 , 46 ]. Therefore, poly l -leucine-incorporating 1-aminocyclopentane-1-carboxylic acid was used as an α-helix-inducing motif.…”

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confidence: 99%

Design and Synthesis of Helical N-Terminal l-Prolyl Oligopeptides Possessing Hydrocarbon Stapling

et al. 2020

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We designed and synthesized helical short oligopeptides with an l-proline on the N-terminus and hydrocarbon stapling on the side chain. Side-chain stapling is a frequently used method for the development of biologically active peptides. Side-chain stapling can stabilize the secondary structures of peptides, and, therefore, stapled peptides may be applicable to peptide-based organocatalysts. Olefin-tethered cis-4-hydroxy-l-proline 1 and l-serine 2 and 8, and (R)-α-allyl-proline 18 were used as cross-linking motifs and incorporated into helical peptide sequences. The Z- and E-selectivities were observed for the ring-closing metathesis reactions of peptides 3 and 11 (i,i+1 series), respectively, while no E/Z-selectivity was observed for that of 19 (i,i+3 series). The stapled peptide B’ catalyzed the Michael addition reaction of 1-methylindole to α,β-unsaturated aldehyde, which was seven times faster than that of unstapled peptide B. Furthermore, the high catalytic activity was retained even at lower catalyst loadings (5 mol %) and lower temperatures (0 °C). The circular dichroism spectra of stapled peptide B’ showed a right-handed helix with a higher intensity than that of unstapled peptide B. These results indicate that the introduction of side-chain stapling is beneficial for enhancing the catalytic activity of short oligopeptide catalysts.

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Synthesis of Chiral α‐Trifluoromethyl α,α‐Disubstituted α‐Amino Acids and Conformational Analysis of L‐Leu‐Based Peptides with (R)‐ or (S)‐α‐Trifluoromethylalanine

et al. 2020

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Various racemic α‐trifluoromethyl α,α‐disubstituted α‐amino acids were synthesized by the reaction of methyl 3,3,3‐trifluoropyruvate imines with Grignard reagents. The optical resolution of racemates using (R)‐1,1’‐bi‐2‐naphthol {(R)‐BINOL} esters gave optically active α‐trifluoromethylated α,α‐disubstituted α‐amino acids, such as α‐trifluoromethylalanine (αCF3Ala), α‐trifluoromethylleucine (αCF3Leu), and α‐trifluoromethylphenylalanine (αCF3Phe). The optically active (R)‐ or (S)‐αCF3Ala was incorporated into the L–Leu‐based pentapeptides, and their preferred conformation in solution and in the crystal state was studied by Fourier transform infrared (FT‐IR) absorption, nuclear Overhauser effect spectroscopy (NOESY) NMR, and circular dichroism (CD) spectra, as well as X‐ray crystallographic analysis. Both L–Leu‐based peptides with (R)‐ or (S)‐αCF3Ala formed right‐handed 310‐helical structures. Both peptide‐backbones at the N‐terminal residues 1–3 were very similar, but the φ and ψ torsion angles of residues 4 and 5 between peptides with (R)‐ or (S)‐ αCF3Ala were different.

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Helical l–Leu‐Based Peptides Having Chiral Five‐Membered Carbocyclic Ring Amino Acids with an Ethylene Acetal Moiety

Cited by 5 publications

References 38 publications

Synthesis of (S)-(−)-Cucurbitine and Conformation of Its Homopeptides

Synthesis of (S)-(−)-Cucurbitine and Conformation of Its Homopeptides

Design and Synthesis of Helical N-Terminal l-Prolyl Oligopeptides Possessing Hydrocarbon Stapling

Synthesis of Chiral α‐Trifluoromethyl α,α‐Disubstituted α‐Amino Acids and Conformational Analysis of L‐Leu‐Based Peptides with (R)‐ or (S)‐α‐Trifluoromethylalanine

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