Sugar-derived oxazolone pseudotetrapeptide as γ-turn inducer and anion-selective transporter

• Sachin S. Burade,
• Sushil V. Pawar,
• Tanmoy Saha,
• Navanath Kumbhar,
• Amol S. Kotmale,
• Manzoor Ahmad,
• Pinaki Talukdar and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2019, 15, 2419–2427, doi:10.3762/bjoc.15.234

• stereochemically stable quaternary carbon center [1]. For example, TAA-derived peptides containing a cyclopropane ring and ʟ/ᴅ-dimethyl tartrate showed an α-turn and form 310-helical conformations in higher oligomers [2][3][4]. While, TAA-derived peptides having a tetrahydrofuran ring demonstrated a β-turn type

• -Trp-Lys-Thy-OH) to get a glycopeptide which acts as an α-turn inducer [12]. Over the last several years, synthetic peptides are known to play a significant role in the design of artificial ion transport systems [13][14][15][16]. Recently, our group has synthesized fluorinated acyclic and cyclic

The diketopiperazine-fused tetrahydro-β-carboline scaffold as a model peptidomimetic with an unusual α-turn secondary structure

• Francesco Airaghi,
• Andrea Fiorati,
• Giordano Lesma,
• Manuele Musolino,
• Alessandro Sacchetti and
• Alessandra Silvani

Beilstein J. Org. Chem. 2013, 9, 147–154, doi:10.3762/bjoc.9.17

• that characterizes the α-turn structure is confirmed by 1H NMR conformational studies. To the best of our knowledge, this scaffold represents one of the rare examples of a designed constrained α-turn mimic. Keywords: α-turn; conformational analysis; diketopiperazine; peptidomimetics; tetrahydro-β

• proteins can also occur thanks to less common substructures, for example involving five amino acids residues, such as the case of the α-turns. Even if a very large majority of α-turn segments form a part of regular α-helices, isolated α-turns have been reported [35], which are stabilized by a 5→1 hydrogen

• -HIV compounds [38]. Other examples of α-turn conformations are described in synthetic peptidomimetics [36][39][40][41][42]. Despite the growing interest in this kind of reverse turn and the need for all kinds of conformationally constrained mimics as tools for medicinal chemistry, the development of