The synthesis of 5-hydroxy chromenes

1985 ◽  
Vol 63 (10) ◽  
pp. 2589-2596 ◽  
Author(s):  
J. W. ApSimon ◽  
L. W. Herman ◽  
C. Huber
Keyword(s):  
Hydrogen Bond ◽  
Oxygen Atom ◽  
Intramolecular Hydrogen Bond ◽  
Hydroxyl Group ◽  
X Ray ◽  
Type Reaction ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond

The synthesis of 2,2-dimethyl-5-hydroxychromene (1d) is described. The synthesis of the analogous 5,7-dihydroxy derivatives, using similar conditions, yields the adduct 9 derived via a Bucherer type reaction. X-ray analysis of 9 demonstrated that a pyrrolidine group was in the 7-position, and that the 5-hydroxyl group was involved in a strong intramolecular hydrogen bond to the 4-keto oxygen atom.

(1′R,3S)-2-Oxo-1-(1′-phenylethyl)piperidine-3-carboxylic acid: a case of a very strong intramolecular hydrogen bond

2004 ◽  
Vol 60 (11) ◽  
pp. o2110-o2112
Author(s):  
Ana-María Lumbreras-García ◽  
Alberto Galindo-Guzmán ◽  
Dino Gnecco ◽  
Joel-Luis Terán ◽  
Sylvain Bernès
Keyword(s):  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Intramolecular Hydrogen Bond ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond

scholarly journals Complexation of Cu(BF4)2 with 3-hydroxyflavone in acetonitrile: quantum chemical calculation

2018 ◽  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Atom ◽  
Intramolecular Hydrogen Bond ◽  
Quantum Chemical ◽  
Phenyl Ring ◽  
Fluorine Atom ◽  
Quantum Chemical Study ◽  
Hydroxyl Group ◽  
Chemical Calculation ◽  
Intramolecular Hydrogen

In the article the results of the quantum chemical study of copper (II) solvato-complexes with acetonitrile (AN), tetrafluoroborate anion (BF4–) and 3-hydroxyflavone (flv) of the composition [Cu(AN)6]2+, [Cu(BF4)(AN)5]+, [Cu(flv)(AN)5]2+, [Cu(flv)(BF4)(AN)4]+ are presented. Calculations were done using density function theory (DFT) on the M06-2X/6-311++G(d,p) level of theory. Obtained results were interpreted in terms of complexes geometry and topology of electron density distribution using non-covalent interactions (NCI) approach. It was shown that flv molecule is a monodentate ligand in copper (II) complexes and coordinates central atom via carbonyl oxygen. Intramolecular hydrogen bond that exists in an isolated flv molecule was found to be broken upon [Cu(flv)(AN)5]2+ complex formation. In [Cu(flv)(AN)5]2+ complex, a significant rotation of phenyl ring over the planar chromone fragment was spotted as a consequence of intramolecular hydrogen bond breaking. Upon inclusion of BF4– anion to the first solvation shell of Cu2+, an intracomplex hydrogen bond was formed between hydrogen atom of hydroxyl group of flv molecule and the closest fluorine atom of BF4– anion. NCI analysis had shown that a hydrogen bond between hydrogen atom of hydroxyl group of flv molecule and the closest fluorine atom of BF4– anion is significantly stronger than intramolecular hydrogen bond in an isolated flv molecule. In addition, flexible phenyl ring of flv molecule in [Cu(flv)(BF4)(AN)4]+ complex was found to be internally stabilized by the weak van der Waals attraction between oxygen atoms of chromone ring and phenyl hydrogens. These evidences led to a conclusion that [Cu(flv)(BF4)(AN)4]+ complex is more stable, comparing to the in [Cu(flv)(AN)5]2+ complex.

scholarly journals Synthesis of a Conformationally Stable Atropisomeric Pair of Biphenyl Scaffold Containing Additional Stereogenic Centers

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 643 ◽  
Author(s):  
Chi-Tung Yeung ◽  
Wesley Chan ◽  
Wai-Sum Lo ◽  
Ga-Lai Law ◽  
Wing-Tak Wong
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Bond Formation ◽  
Aldol Reaction ◽  
Spatial Arrangement ◽  
Hydroxyl Groups ◽  
Hydrogen Bond Formation ◽  
X Ray ◽  
Stereogenic Centers ◽  
Intramolecular Hydrogen

The synthesis of a new CF3-containing stereogenic atropisomeric pair of ortho-disubstituted biphenyl scaffold is presented. The atropisomers are surprisingly conformationally stable for isolation. X-ray structures show that their stability comes from an intramolecular hydrogen bond formation from their two hydroxyl groups and renders the spatial arrangement of their peripheral CF3 and CH3 groups very different. The synthesized stereogenic scaffold proved to be effective in catalyzing the asymmetric N-nitroso aldol reaction of enamine and nitrosobenzene. Compared to similar scaffolds without CF3 groups, one of our atropisomer exhibits an increase in enantioselectivity in this reaction.

Aromatic amides. IX. Temperature effects on the N.M.R. spectra of substituted acetanilides

1974 ◽  
Vol 27 (12) ◽  
pp. 2617 ◽  
Author(s):  
ID Rae
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shift ◽  
Benzene Ring ◽  
Intramolecular Hydrogen Bond ◽  
Temperature Effects ◽  
Dimethyl Sulphoxide ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond ◽  
Ortho Substituent

N.m.r. spectra have been measured for several anilides in dimethyl sulphoxide solution for temperatures in the range 40-140�. The change of the N-H chemical shift with temperature depends on the nature of the ortho substituent on the benzene ring, being least when a strong intramolecular hydrogen bond is possible between the amide N-H and the ortho substituent. For 2?-nitroanilides, the 6?- proton becomes increasingly deshielded as the temperature is raised.

Temperature dependence of chemical shifts of protons in hydrogen bonds. Experimental evidence on an intramolecular hydrogen bond

1968 ◽  
Vol 46 (17) ◽  
pp. 2865-2868 ◽  
Author(s):  
T. Schaefer ◽  
G. Kotowycz
Keyword(s):  
Hydrogen Bond ◽  
Carbon Tetrachloride ◽  
Chemical Shift ◽  
Hydrogen Bonds ◽  
Temperature Dependence ◽  
Intramolecular Hydrogen Bond ◽  
Chemical Shifts ◽  
Hydroxyl Proton ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond

A temperature dependence of the chemical shift of the hydroxyl proton in the strong intramolecular hydrogen bond in 3,5-dichlorosalicylaldehyde is observed in carbon tetrachloride and benzene-d6 solutions. Its magnitude of 0.25 to 0.30 × 10−2 p.p.m. per ° C over a range of 100 °C is in agreement with the model described by Muller and Reiter (1).

Heterocyclic Tautomerism. The Solution and Crystal Structures of 1-(4',6'-Dimethylpyrimidin-2'-yl)-3-methylpyrazol-5-ol

1984 ◽  
Vol 37 (2) ◽  
pp. 459 ◽  
Author(s):  
PJ Steel ◽  
AR Whyte
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Crystal Structures ◽  
Intramolecular Hydrogen Bond ◽  
Title Compound ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond

Both in the solid state and in solution, the title compound is shown to exist as the OH tautomer (3), which is stabilized by a strong intramolecular hydrogen bond. Crystals of the pyrazol-5-ol (3) are monoclinic: P 21/c, a 9.692(5), b 7.371(5), c 15.345(8) �, β 106.07(4)�, Z 4; the structure was refined to R 0.072 and Rw 0.062.

scholarly journals The stereochemical structure of disodium dl-glycerol 3-phosphate hexahydrate, the d isomer of which is an inhibitor of triose phosphate isomerase

1972 ◽  
Vol 130 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Ruth H. Fenn ◽  
Geoffrey E. Marshall
Keyword(s):  
Complex System ◽  
Aqueous Solution ◽  
Hydrogen Bond ◽  
Hydroxyl Group ◽  
Ester Bond ◽  
Stereochemical Structure ◽  
X Ray ◽  
Structure Factors ◽  
Lending Library ◽  
Intramolecular Hydrogen

The stereochemistry of dl-glycerol 3-phosphate was studied by X-ray-crystallographic techniques. All the bond lengths and angles are within normally accepted limits except the ester bond, which is one of the largest yet noted, being 0.1637nm. The conformation of the molecule is such that an intramolecular hydrogen bond is formed between the hydroxyl group on the β-carbon atom and the phosphate group. The crystal, which was grown by alcohol diffusion into an aqueous solution, is held together by sodium co-ordination and a complex system of hydrogen bonds. A table of the observed and calculated structure factors, ǀFobs.ǀ and Fcalc., has been deposited as Supplementary Publication 50010 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1972) 126, 5.

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