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

2013 ◽  
Vol 9 ◽  
pp. 147-154 ◽  
Author(s):  
Francesco Airaghi ◽  
Andrea Fiorati ◽  
Giordano Lesma ◽  
Manuele Musolino ◽  
Alessandro Sacchetti ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Ring System ◽  
Peptide Ligands ◽  
Conformational Studies ◽  
H Nmr ◽  
Fused Ring ◽  
Conformational Freedom ◽  
Turn Structure ◽  
Fused Ring System ◽  
Turn Mimic

Aiming at restricting the conformational freedom of tryptophan-containing peptide ligands, we designed a THBC (tetrahydro-β-carboline)-DKP (diketopiperazine)-based peptidomimetic scaffold capable of arranging in an unusual α-turn conformation. The synthesis is based on a diastereoselective Pictet–Spengler condensation to give the THBC core, followed by an intramolecular lactamization to complete the tetracyclic THBC-DKP fused ring system. The presence of conformers bearing the intramolecular thirteen-membered hydrogen bond 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.

scholarly journals Crystal structure of ethyl 2-amino-4-(4-chlorophenyl)-4H-1-benzothieno[3,2-b]pyran-3-carboxylate

2015 ◽  
Vol 71 (8) ◽  
pp. o619-o620
Author(s):  
Mohamed Bakhouch ◽  
Asmae Mahfoud ◽  
Mohamed El Yazidi ◽  
Mohamed Saadi ◽  
Lahcen El Ammari
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Ring System ◽  
The Other ◽  
Bond Forming ◽  
Compound C ◽  
Fused Ring ◽  
The Mean ◽  
Fused Ring System ◽  
Ring Motif

The title compound, C20H16ClNO3S, is built up from three fused rings, one five- and two six-membered rings, linked to a 3-ethoxycarbonyl group and to a 4-chlorophenyl ring. The hydropyran ring has a flattened envelope conformation, with the C atom substituted by the 4-chlorophenyl ring as the flap (displaced by 0.077 (2) Å from the plane through the other atoms). The fused three-ring system is quasi-planar (r.m.s. deviation = 0.057 Å), with the largest deviation from the mean plane being 0.106 (1) Å for the C atom substituted by the 4-chlorophenyl ring. The 4-chlorophenyl ring is approximately perpendicular to the mean plane of the fused ring system, as indicated by the dihedral angle of 77.32 (6)° between their mean planes. There is an intramolecular N—H...O hydrogen bond forming anS(6) ring motif. In the crystal, molecules are linked by pairs of N—H...O hydrogen bonds, forming inversion dimers with anR22(12) ring motif. There are also short intermolecular Cl...O interactions present [3.1226 (12) Å] between neighbouring molecules.

scholarly journals Crystal structure of ethyl 2-amino-4-(4-methoxyphenyl)-4H-1-benzothieno[3,2-b]pyran-3-carboxylate

2015 ◽  
Vol 71 (5) ◽  
pp. o366-o367
Author(s):  
Mohamed Bakhouch ◽  
Abdelali Kerbal ◽  
Mohamed El Yazidi ◽  
Mohamed Saadi ◽  
Lahcen El Ammari
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Ring System ◽  
Membered Ring ◽  
Carboxylate Group ◽  
Compound C ◽  
Fused Ring ◽  
The Mean ◽  
Fused Ring System

The molecule of the title compound, C21H19NO4S, features a fused ring system whereby a five-membered ring is flanked by two six-membered rings. This is linked to an ethyl 3-carboxylate group and to a methoxybenzene group. The fused-ring system is quasi-planar, with the greatest deviation from the mean plane being 0.131 (1) Å for the methine C atom. The plane through the methoxybenzene ring is nearly perpendicular to that through the fused-ring system, as indicated by the dihedral angle of 85.72 (6)°. An intramolecular N—H...O hydrogen bond is noted. In the crystal, molecules are linked by N—H...O hydrogen bonds, forming layers that stack along theaaxis.

scholarly journals 3,4,6-Triamino-N-phenylthieno[2,3-b]pyridine-2-carboxamide

2014 ◽  
Vol 70 (7) ◽  
pp. o805-o805
Author(s):  
Shaaban K. Mohamed ◽  
Joel T. Mague ◽  
Mehmet Akkurt ◽  
Bahgat R. M. Hussein ◽  
Mustafa R. Albayati
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Phenyl Ring ◽  
Three Dimensional ◽  
Ring System ◽  
Compound C ◽  
Dimensional Network ◽  
Fused Ring ◽  
Fused Ring System

In the title compound, C14H13N5OS, the dihedral angle between the fused ring system (r.m.s. deviation = 0.028 Å) and the phenyl ring is 48.24 (4)°. The molecule features both an intramolecular N—H...O and an N—H...N hydrogen bond. In the crystal, molecules are linked by N—H...O and N—H...N hydrogen bonds, generating a three-dimensional network. A weak N—H...π interaction is also observed.

scholarly journals Crystal structure of 7,8-benzocoumarin-4-acetic acid

2015 ◽  
Vol 71 (8) ◽  
pp. o617-o618
Author(s):  
R. Ranga Swamy ◽  
Ramakrishna Gowda ◽  
K. V. Arjuna Gowda ◽  
Mahantesha Basanagouda
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Acetic Acid ◽  
Hydrogen Bonds ◽  
Torsion Angle ◽  
Ring System ◽  
Side Chain ◽  
Acceptor Atom ◽  
Fused Ring ◽  
Fused Ring System

The fused-ring system in the title compound [systematic name: 2-(2-oxo-2H-benzo[h]chromen-4-yl)acetic acid], C15H10O4, is almost planar (r.m.s. deviation = 0.031 Å) and the Car—C—C=O (ar = aromatic) torsion angle for the side chain is −134.4 (3)°. In the crystal, molecules are linked by O—H...O hydrogen bonds, generating [100]C(8) chains, where the acceptor atom is the exocyclic O atom of the fused-ring system. The packing is consolidated by a very weak C—H...O hydrogen bond to the same acceptor atom. Together, these interactions lead to undulating (001) layers in the crystal.

scholarly journals Crystal structure of 1,7,8,9-tetrachloro-4-(2-fluorobenzyl)-10,10-dimethoxy-4-azatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione

2015 ◽  
Vol 71 (1) ◽  
pp. o32-o32
Author(s):  
Jia-liang Zhong ◽  
Jia-wei Hou ◽  
Li-hong Liu ◽  
He Liu
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Title Compound ◽  
Ring System ◽  
The Other ◽  
Pyrrolidine Ring ◽  
Compound C ◽  
Fused Ring ◽  
Adjacent Molecule ◽  
Fused Ring System

In the title compound, C17H12Cl4FNO4, the configuration of the cycloalkene skeleton isendo,cis. The benzene ring is twisted by 71.01 (11)° from the attached pyrrolidine ring. In the crystal, one of the methine groups of the fused-ring system forms a weak C—H...O hydrogen bond. The other methine groups participates in a C—H...F interaction to the same adjacent molecule. Together, these generate [010] chains.

scholarly journals Crystal structure of 2-methylamino-3-nitro-4-p-tolylpyrano[3,2-c]chromen-5(4H)-one

2015 ◽  
Vol 71 (3) ◽  
pp. o158-o159
Author(s):  
J. Govindaraj ◽  
Y. AaminaNaaz ◽  
Jayabal Kamalraja ◽  
Paramasivam T. Perumal ◽  
A. SubbiahPandi
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Title Compound ◽  
Molecular Conformation ◽  
Ring System ◽  
The Other ◽  
Pyran Ring ◽  
Compound C ◽  
Fused Ring ◽  
Fused Ring System

In the racemic title compound, C20H16N2O5, the pyran ring adopts a shallow envelope conformation, with the stereogenic C atom displaced from the other atoms by 0.273 (2) Å. The dihedral angle between the fused-ring system and the pendantp-tolyl group is 87.62 (7)°. The molecular conformation is consolidated by an intramolecular N—H...O hydrogen bond, which generates anS(6) ring. In the crystal, molecules are linked by C—H...O interactions, resulting in [010] chains.

scholarly journals Ethyl 2-amino-4-(3-chlorophenyl)-5,10-dioxo-5,10-dihydro-4H-benzo[g]chromene-3-carboxylate

2009 ◽  
Vol 65 (6) ◽  
pp. o1324-o1324
Author(s):  
Xiao Hu ◽  
Song Lei ◽  
Chang-Sheng Yao
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Crystal Packing ◽  
Ring System ◽  
Membered Ring ◽  
Fused Ring ◽  
Title Molecule ◽  
Fused Ring System

The title molecule, C22H16ClNO5, was obtained by the reaction of (E)-ethyl 3-(3-chlorophenyl)-2-cyanoacrylate and 2-hydroxynaphthalene-1,4-dione catalysed by triethylamine in ethanol. In the crystal structure, the chlorobenzene ring makes a dihedral angle of 88.63 (4)° with the fused ring system. The six-membered ring formed by an intramolecular N—H...O hydrogen bond is almost planar. The crystal packing is stabilized by N—H...O hydrogen bonds.

scholarly journals Crystal structure of (3S*,4S*,4aS*,5R*,6R*,6aS*,7R*,11aS*,11bR*)-5,6-bis(benzoyloxy)-3,4a-dihydroxy-4,7,11b-trimethyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodecahydrophenanthro[3,2-b]furan-4-carboxylic acid methanol monosolvate

2015 ◽  
Vol 71 (10) ◽  
pp. o739-o740
Author(s):  
Sadaf Siddiqui ◽  
Osayemwenre Erharuyi ◽  
Abiodun Falodun ◽  
M. Iqbal Choudhary ◽  
Sammer Yousuf
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Ring System ◽  
Dihedral Angles ◽  
Compound C ◽  
Fused Ring ◽  
Phenyl Rings ◽  
The Mean ◽  
Fused Ring System

The title compound, C34H36O9·CH3OH, is a diterpenoid isolated from the roots ofCaesalpinia pulcherrima(L.) Swartz. The threetrans-fused six-membered rings are in chair, chair and half-chair conformations. The mean plane of this fused-ring system makes dihedral angles of 67.95 (15) and 83.72 (14)° with the two phenyl rings of the benzoyloxy groups. An intramolecular C—H...O hydrogen bond is observed. In the crystal, molecules are linkedviaO—H...O hydrogen bonds, forming an infinite chain along theb-axis direction.

Configurational and conformational studies on condensation products of biogenic amines with 2,5-anhydro-D-mannose

1985 ◽  
Vol 63 (11) ◽  
pp. 2915-2921 ◽  
Author(s):  
Ian M. Piper ◽  
David B. MacLean ◽  
Romolo Faggiani ◽  
Colin J. L. Lock ◽  
Walter A. Szarek
Keyword(s):  
Hydrogen Bond ◽  
Intermolecular Hydrogen Bond ◽  
Direct Methods ◽  
Conformational Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Twist Conformation ◽  
Cell Dimensions ◽  
Internal Hydrogen Bond

The products of a Pictet–Spengler condensation of tryptamine and of histamine with 2,5-anhydro-D-mannose have been studied by X-ray crystallography to establish their absolute configuration. 1(S)-(α-D-Arabinofuranosyl)-1,2,3,4-tetrahydro-β-carboline (1), C16H20N20O4, is monoclinic, P21 (No. 4), with cell dimensions a = 13.091(4), b = 5.365(1), c = 11.323(3) Å, β = 115.78(2)°, and Z = 2. 4-(α-D-Arabinofuranosyl)imidazo[4,5-c]-4,5,6,7-tetrahydropyridine (3), C11H17N3O4, is orthorhombic, P212121 (No. 19), with cell dimensions a = 8.118(2), b = 13.715(4), c = 10.963(3) Å, and Z = 4. The structures were determined by direct methods and refined to R1 = 0.0514, R2 = 0.0642 for 3210 reflections in the case of 1, and to R1 = 0.0312, R2 = 0.0335 for 1569 reflections in the case of 3. Bond lengths and angles within both molecules are normal and agree well with those observed in related structures. In 3 the base and sugar adopt a syn arrangement, which is maintained by an internal hydrogen bond between O(2′) and N(3). The sugar adopts a normal 2T3 twist conformation. The sugar has the opposite anti arrangement in the β-carboline 1 and the conformation of the sugar is unusual; it is close to an envelope conformation with O(4′) being the atom out of the plane. This conformation is caused by a strong intermolecular hydrogen bond from O(5′) in a symmetry-related molecule to O(4′). Both compounds are held together in the crystal by extensive hydrogen-bonding networks. The conformations of the compounds in solution have been investigated by 1H nmr spectroscopy, and the results obtained were compared with those obtained by X-ray crystallography for 1 and 3.

scholarly journals NEW ROUTES TO 1,2-DIAZOLES WITH A FUSED RING SYSTEM BY REDUCTIVE AND OXIDATIVE CYCLIZATIONS

1974 ◽  
Vol 3 (9) ◽  
pp. 951-954 ◽  
Author(s):  
Joung Hee Lee ◽  
Akira Matsumoto ◽  
Masayuki Yoshida ◽  
Osamu Simamura
Keyword(s):  
Ring System ◽  
Oxidative Cyclizations ◽  
Fused Ring ◽  
Fused Ring System
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