ChemInform Abstract: EVIDENCE IN SUPPORT OF TETRAOXASPIROPHOSPHORANE INTERMEDIATES WITH A SIX-MEMBERED RING AND A PHOSPHORUS-HYDROGEN BOND IN INTRAMOLECULAR TRANSESTERIFICATION REACTIONS

1985 ◽  
Vol 16 (43) ◽  
Author(s):  
J. J. C. VAN LIER ◽  
R. J. M. HERMANS ◽  
H. M. BUCK
Keyword(s):  
Hydrogen Bond ◽  
Membered Ring

scholarly journals 14,15-Didehydrohellebrigenin

2012 ◽  
Vol 68 (6) ◽  
pp. o1614-o1615
Author(s):  
Tong Yu ◽  
Hai-Yan Tian ◽  
Xiao-Feng Yuan ◽  
Shu-Zhi Hu ◽  
Ren-Wang Jiang
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Lactone Ring ◽  
Three Dimensional ◽  
Membered Ring ◽  
Envelope Conformation ◽  
Compound C ◽  
Dimensional Network ◽  
Hydroxy Groups

The title compound, C24H30O5, is the didehydro product of the steroid hellebrigenin (systematic name: 3β,5,14-trihydroxy-19-oxo-5β-bufa-20,22-dienolide). It consists of three cyclohexane rings (A, B and C), a five-membered ring (D) and a six-membered lactone ring (E). The stereochemistry of the ring junctions are A/B cis, B/C trans and C/D cis. Cyclohexane rings A, B and C have normal chair conformations. The five-membered ring D with the C=C bond adopts an envelope conformation. Lactone ring E is essentially planar with a mean derivation of 0.006 (4) Å and is β-oriented at the C atom of ring D to which it is attached. There is an O—H...O hydrogen bond in the molecule involving the hydroxy groups. In the crystal, O—H...O hydrogen bonds link the molecules into chains propagating along [010]. The chains are linked by C—H...O contacts into a three-dimensional network.

Left-Handed Helix of Three-Membered Ring Amino Acid Homopeptide Interrupted by an N–H···Ethereal O-Type Hydrogen Bond

2018 ◽  
Vol 20 (24) ◽  
pp. 7830-7834 ◽  
Author(s):  
Yurie Koba ◽  
Atsushi Ueda ◽  
Makoto Oba ◽  
Mitsunobu Doi ◽  
Takuma Kato ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Amino Acid ◽  
Membered Ring ◽  
Left Handed ◽  
Type Hydrogen Bond

scholarly journals 2-Oxo-2H-chromen-7-yl 4-methylbenzoate

IUCrData ◽  
2018 ◽  
Vol 3 (7) ◽  
Author(s):  
Abdoulaye Djandé ◽  
Akoun Abou ◽  
Félix Kini ◽  
Konan René Kambo ◽  
Michel Giorgi
Keyword(s):  
Hydrogen Bond ◽  
Title Compound ◽  
Acute Angle ◽  
Membered Ring ◽  
Hirshfeld Surface ◽  
Supramolecular Interactions ◽  
Stacking Interactions ◽  
Weak Hydrogen Bond ◽  
Compound C ◽  
Benzene Rings

In the title compound, C17H12O4, the benzoate ring is oriented at an acute angle of 60.14 (13)° relative to the coumarin plane (r.m.s. deviation = 0.006 Å). This conformation is stabilized by an intramolecular C—H...O weak hydrogen bond, which forms a five-membered ring. Also present are π–π stacking interactions between neighbouring pyrone and benzene rings [centroid-to-centroid distances in the range 3.6286 (1)–3.6459 (1) Å] and C=O...π interactions [O...centroid distances in the range 3.2938 (1)–3.6132 (1) Å]. Hirshfeld surface analysis has been used to confirm and quantify the supramolecular interactions.

Polysulfonylamine, CXXVI [1] Wasserstoffbrücken in kristallinen Onium-dimesylamiden: Ein robustes Achtring-Synthon in Koexistenz mit einem dritten Wasserstoffbrückenmotiv - Cyclodimere, Ketten, supramolekulare Bindungsisomere und ein fünffach verwobenes dreidimensionales (C-H ∙∙∙ O - Netzwerk / Polysulfonylamines, CXXVI [1] Hydrogen Bonding in Crystalline Onium Dimesylamides: A Robust Eight- Membered Ring Synthon in Coexistence with a Third Hydrogen Bonding Motif - Cyclodimers, Chains, Supramolecular Linkage Isomers, and a Quintuply Interwoven Three-Dimensional C - H ∙∙∙ O Network

2000 ◽  
Vol 55 (8) ◽  
pp. 738-752 ◽  
Author(s):  
Oliver Moers ◽  
Karna Wijaya ◽  
Ilona Lange ◽  
Armand Blaschette ◽  
Peter G. Jones
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Crystal Engineering ◽  
Ion Pairs ◽  
Three Dimensional ◽  
Membered Ring ◽  
Monoclinic Space Group ◽  
Hydrogen Bond Donor ◽  
Linkage Isomers ◽  
Ionic Solids

As an exercise in crystal engineering, low-temperature X-ray structures were determined for six rationally designed ionic solids of general formula BH+(MeSO2)2N−, where BH+ is 2-aminopyridinium (2, monoclinic, space group P21/c, Z = 4), 2-aminopyrimidinium (3, orthorhombic, Pbca, Z = 8), 2-aminothiazolium (4, orthorhombic, Pbcn, Z = 8), 2-amino-6-methylpyridinium (5, solvated with 0.5 H20, monoclinic, C2/c, Z = 8), 2-amino-1,3,4-thiadiazolium (6, triclinic, P1̄, Z = 2), or 2-amino-4,6-dimethylpyrimidinium (7, orthorhombic. Fdd2, Z = 16). The onium cations in question exhibit a trifunctional hydrogen-bond donor sequence H − N (H*)-C (sp2) − N − H , which is complementary to an O − S (sp3)−N fragment of the anion and simultaneously expected to form a third hydrogen bond via the exocyclic N − H* donor. Consequently, all the crystal packings contain cation-anion pairs assembled by an N − H ∙∙∙ N and an N −H ∙∙∙ O hydrogen bond, these substructures being mutually associated through an N − H* ∙∙∙ O bond. For the robust eight-membered ring synthon within the ion pairs [graph set N2 = R22(8), antidromic], two supramolecular isomers were observed: In 2 and 3, N − H ∙∙∙ N originates from the ring NH donor and N − H ∙∙∙ O from the exocyclic amino group, whereas in 4-7 these connectivities are reversed. The third hydrogen bond, N − H*∙∙∙ O , leads either to chains of ion pairs (generated by a 21 transformation in 2-4 or by a glide plane in 5) or to cyclic dimers of ion pairs (Ci symmetric in 6, C2-symmetric in 7). The overall variety of motifs observed in a small number of structures reflects the limits imposed on the prediction of hydrogen bonding patterns. Owing to the excess of potential acceptors over traditional hydrogen-bond donors, several of the structures display prominent non-classical secondary bonding. Thus, the cyclodimeric units of 6 are associated into strands through short antiparallel O ∙∙∙ S(cation) interactions. In the hemihydrate 5, two independent C-H(cation) ∙∙∙ O bonds generate a second antidromic R22(8) pattern, leading to sheets composed of N − H ∙∙∙ N/O connected catemers; the water molecules are alternately sandwiched between and O - H ∙∙∙ O bonded to the sheets to form bilayers, which are cross-linked by a third C − H (cation ) ∙∙∙ O contact. The roof-shaped cyclodimers occurring in 7 occupy the polar C2 axes parallel to z and build up hollow Car− H ∙∙∙ O bonded tetrahedral lattices; in order to fill their large empty cavities, five translationally equivalent lattices mutually interpenetrate.

Similar molecular constitutions but different conformations and different supramolecular assemblies in two related fused tetracyclic benzo[b]pyrimido[5,4-f]azepine derivatives

2016 ◽  
Vol 72 (1) ◽  
pp. 52-56 ◽  
Author(s):  
Lina M. Acosta Quintero ◽  
Isidro Burgos ◽  
Alirio Palma ◽  
Justo Cobo ◽  
Christopher Glidewell
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Heterocyclic Compounds ◽  
Pyridine Ring ◽  
Membered Ring ◽  
Methyl Substituent ◽  
Π Interactions ◽  
Π Stacking Interaction ◽  
And Inversion ◽  
Axial Site

A simple and effective two-step approach to tricyclic pyrimidine-fused benzazepines has been adapted to give the tetracyclic analogues. In (RS)-8-chloro-6-methyl-1,2,6,7-tetrahydropyrimido[5′,4′:6,7]azepino[3,2,1-hi]indole, C15H14ClN3, (I), the five-membered ring adopts an envelope conformation, as does the reduced pyridine ring in (RS)-9-chloro-7-methyl-2,3,7,8-tetrahydro-1H-pyrimido[5′,4′:6,7]azepino[3,2,1-ij]quinoline, C16H16ClN3, (II). However, the seven-membered rings in (I) and (II) adopt very different conformations, with the result that the methyl substituent occupies a quasi-axial site in (I) but a quasi-equatorial site in (II). The molecules of (I) are linked by C—H...N hydrogen bonds to formC(5) chains and inversion-related pairs of chains are linked by a π–π stacking interaction. A combination of a C—H...π hydrogen bond and two C—Cl...π interactions links the molecules of (II) into complex sheets. Comparisons are made with some similar fused heterocyclic compounds.

scholarly journals Zur Kristallchemie ungeladener Phosphazen-Basen, I [1] Strukturen zweier Hydrate und eines Acetats von Tris(dimethylamino)methyliminophosphoran / Crystal Chemistry of Uncharged Phosphazene Bases, I [1] Structures of Two Hydrates and an Acetate of Tris(dimethylamino) methyliminophosphorane

1996 ◽  
Vol 51 (10) ◽  
pp. 1369-1374 ◽  
Author(s):  
Frank Hartmann ◽  
Dietrich Mootz ◽  
Reinhard Schwesinger
Keyword(s):  
Hydrogen Bond ◽  
Base Cation ◽  
Ion Pair ◽  
Membered Ring ◽  
Water Molecules ◽  
Formula Unit ◽  
Acid Anion ◽  
Great Strength ◽  
Centrosymmetric Dimer ◽  
Additional Water

Two hydrates and an acetate of the uncharged, very strong phosphazene base tris(dimethylamino)methyliminophosphorane, (Me2N)3P=NMe (for short Me-P1), have been characterized by their crystal structures. A monohydrate, Me-P1 · H2O , mp. 3°C, is monoclinic with space group P21/n and Z = 4 formula units per unit cell of dimensions a = 8.585, b = 11.107, c = 13.083 Å, and β = 97.76° at -30°C. Another hydrate, Me-P1 · 1.75 H2O, mp. - 11°C. is triclinic with P1̅, Z = 4, a = 7.924, b = 11.768, c = 14.257 Å, α = 89.70°,β = 86.30°, and 7 = 86.54° at -100°C. An acetate, Me-P1 · CH3COOH, mp. 88°C, is also triclinic with P1̅, Z = 2, a = 7.558, b = 8.193, c = 11.431 A, a = 93.60°, β = 96.52°, and γ = 92.12° at-100°C. In the hydrate Me-P1 · H2O , a centrosymmetric dimer of the formula unit is formed by O-H···N hydrogen bonds arranged in a four-membered ring. In the hydrate Me-P1 · 1.75 H2O , two rings of this kind are linked by additional water molecules into an infinite chain each. Both hydrate structures are those of molecular adducts, in spite of the great strength of the base. By contrast, the structure of the acetate Me-P1 · CH3COOH is clearly ionic, with an ion pair being formed by a bifurcated (three-center) hydrogen bond N-H(···O)2 from the protonated N atom of the base cation to both O atoms of one and the same acid anion.

scholarly journals 1-Phenyl-3H-2,3-benzodiazepin-4(5H)-one

2012 ◽  
Vol 68 (8) ◽  
pp. o2443-o2443
Author(s):  
Ballo Daouda ◽  
Frédéric Bihel ◽  
Mouhamadou Lamine Doumbia ◽  
El Mokhtar Essassi ◽  
Seik Weng Ng
Keyword(s):  
Hydrogen Bond ◽  
Double Bond ◽  
Title Compound ◽  
Membered Ring ◽  
Unit Cell ◽  
Orthorhombic Unit Cell ◽  
Compound C

The seven-membered ring in the title compound, C15H12N2O, adopts a boat-shaped conformation (with the methylene C atom as the prow and the double-bond C=N pair of atoms as the stern). In the crystal, adjacent molecules are linked by an N—H...O hydrogen bond to generate helical chains running along theaaxis of the orthorhombic unit cell.

scholarly journals Crystal structure of ethyl (4R)-2-amino-7-hydroxy-4-phenyl-4H-chromene-3-carboxylate

2015 ◽  
Vol 71 (7) ◽  
pp. o519-o520
Author(s):  
Joel T. Mague ◽  
Shaaban K. Mohamed ◽  
Mehmet Akkurt ◽  
Sabry H. H. Younes ◽  
Mustafa R. Albayati
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Phenyl Ring ◽  
Membered Ring ◽  
Two Dimensional ◽  
Crystal Stability ◽  
Compound C ◽  
Dimensional Network

In the title compound, C18H17NO4, the dihedral angle between the phenyl ring and the fused six-membered ring is 77.65 (4)°. The conformation of the molecule is determined in part by an intramolecular N—H...O hydrogen bond between the amino H atom and the carbonyl O atom, forming anS(6) motif. In the crystal, molecules are linked into N—H...O hydrogen-bonded inversion dimers which are then connected into chains along [001], forming a two-dimensional network parallel to (100)viaO—H...O hydrogen bonds. C—H...O interactions further contribute to the crystal stability. The ethyl group is disordered over two sets of sites in a 0.801 (5):0.199 (5) ratio.

scholarly journals Relative substituent orientation in the structure ofcis-3-chloro-1,3-dimethyl-N-(4-nitrophenyl)-2-oxocyclopentane-1-carboxamide

2014 ◽  
Vol 70 (9) ◽  
pp. 121-123
Author(s):  
Matthias Zeller ◽  
Jonas Warneke ◽  
Vladimir Azov
Keyword(s):  
Hydrogen Bond ◽  
Crystal Packing ◽  
Membered Ring ◽  
Amide Group ◽  
Aromatic Rings ◽  
Methyl Group ◽  
Compound C ◽  
The Mean ◽  
Graph Set ◽  
Intramolecular Hydrogen

The structure of the title compound, C14H15ClN2O4, prepared by reaction of a methacryloyl dimer with nitroaniline, was determined to establish the relative substituent orientation on the cyclopentanone ring. In agreement with an earlier proposed reaction mechanism, the amide group and the methyl group adjacent to the chloro substituent adopt equatorial positions and relativecisorientation, whereas the Cl substituent itself and the methyl group adjacent to the amide have axial orientations relative to the mean plane of the five-membered ring. The conformation of the molecule is stabilized by one classical N—H...O (2.18 Å) and one non-classical C—H...O (2.23 Å) hydrogen bond, each possessing anS(6) graph-set motif. The crystal packing is defined by several non-classical intramolecular hydrogen bonds, as well as by partial stacking of the aromatic rings.

scholarly journals 4-{[Bis(2-hydroxyethyl)amino]methyl}-6-methoxy-2H-chromen-2-one

2012 ◽  
Vol 68 (8) ◽  
pp. o2413-o2414
Author(s):  
Reshma Naik ◽  
Ravish Sankolli ◽  
G. N. Anil Kumar ◽  
T. N. Guru Row ◽  
Manohar V. Kulkarni
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Membered Ring ◽  
Side Chains ◽  
Stacking Interactions ◽  
Compound C ◽  
Π Stacking ◽  
Centroid Distance

In the title compound, C15H19NO5, an intramolecular O—H...O hydrogen bond links the hydroxyethyl side chains, forming a seven-membered ring. In the crystal, molecules are linked into chainsviaO—H...O hydrogen bonds along thebaxis. Further, molecules are linked by weak intermolecular C—H...O and π–π stacking interactions [centroid–centroid distance = 3.707 (4) Å].

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