Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Camphanes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2000

Why (1S)-Camphanates Are Excellent Resolving Agents for Helicen-1-ols and Why They Can Be Used to Analyze Absolute Configurations.

The questions considered in this paper are why, as agents for resolving helicenols, camphanate esters are particularly effective, and why, in all 19 examples studied, when the (1S)-camphanates of (P)- and (M)-helicen-1-ols are chromatographed on silica gel, the former has the lower R(f)(). Models are proposed for the favored conformations of the esters, and to support the models, evidence is provided from five X-ray diffraction analyses and four ROESY analyses supplemented by molecular mechanics calculations. The essential discovery is that, presumably to avoid a steric interaction between a methyl on the camphanate's bridge and the helicene skeleton, the O=CCO conformation is anti-periplanar in (M)-helicenol camphanates and syn-periplanar in (P)-helicenol camphanates. In the former, the lactone carbonyl points toward the helicene ring system, and in the latter, it points away.

Journal Article↗
PubMed2006

Characteristic motion of a camphanic acid disk on water depending on the concentration of Triton X-100.

As a simple autonomous motor, the self-motion of a camphanic acid disk on the aqueous phase with a neutral surfactant (Triton X-100) was investigated. Whereas only continuous motion was observed on water, intermittent motion (alternating between motion and rest) was observed upon addition of Triton X-100. Under the experimental conditions that gave intermittent motion, the surface tension of the aqueous phase changed periodically, synchronous with the contact angle around the camphanic acid disk. These characteristics of self-motion are discussed in relation to the surface tension depending on the concentration of camphanic acid with or without Triton X-100 as the driving force of the motion.

Journal Article↗
PubMed1991

Crystal structures of cytochrome P-450CAM complexed with camphane, thiocamphor, and adamantane: factors controlling P-450 substrate hydroxylation.

X-ray crystal structures have been determined for complexes of cytochrome P-450CAM with the substrates camphane, adamantane, and thiocamphor. Unlike the natural substrate camphor, which hydrogen bonds to Tyr96 and is metabolized to a single product, camphane, adamantane and thiocamphor do not hydrogen bond to the enzyme and all are hydroxylated at multiple positions. Evidently the lack of a substrate-enzyme hydrogen bond allows substrates greater mobility in the active site, explaining this lower regiospecificity of metabolism as well as the inability of these substrates to displace the distal ligand to the heme iron. Tyr96 is a ligand, via its carbonyl oxygen atom, to a cation that is thought to stabilize the camphor-P-450CAM complex [Poulos, T. L., Finzel, B. C., & Howard, A. J. (1987) J. Mol. Biol. 195, 687-700]. The occupancy and temperature factor of the cationic site are lower and higher, respectively, in the presence of the non-hydrogen-bonding substrates investigated here than in the presence of camphor, underscoring the relationship between cation and substrate binding. Thiocamphor gave the most unexpected orientation in the active site of any of the substrates we have investigated to date. The orientation of thiocamphor is quite different from that of camphor. That is, carbons 5 and 6, at which thiocamphor is primarily hydroxylated [Atkins, W. M., & Sligar, S. G. (1988) J. Biol. Chem. 263, 18842-18849], are positioned near Tyr96 rather than near the heme iron. Therefore, the crystallographically observed thiocamphor-P-450CAM structure may correspond to a nonproductive complex. Disordered solvent has been identified in the active site in the presence of uncoupling substrates that channel reducing equivalents away from substrate hydroxylation toward hydrogen peroxide and/or "excess" water production. A buried solvent molecule has also been identified, which may promote uncoupling by moving from an internal location to the active site in the presence of highly mobile substrates.

Adamantane↗
PubMed2004

Resolution of (S,S)-4-(2,2,4-trimethylchroman-4-yl)phenyl camphanate and its 4-chromanyl epimer by crystallization.

Dianin's compound (4-p-hydroxyphenyl-2,2,4-trimethylchroman) has been resolved by crystallization of the (S)-(-)-camphanic esters (S,S)- and (R,S)-4-(2,2,4-trimethylchroman-4-yl)phenyl 4,7,7-trimethyl-3-oxo-2-oxabicyclo[2.2.1]heptane-1-carboxylate, both C28H32O5, from 2-methoxyethanol, yielding the pure S,S diastereomer. The relative stereochemistry of both diastereomers has been determined by X-ray crystallography, from which the absolute stereochemistry could be deduced from the known configuration of the camphanate moiety. The crystallographic conformations have been analysed, including the 1:1 disorder of the R,S diastereomer.

Journal Article↗
PubMed1990

Biosynthesis of monoterpenes: stereochemistry of the coupled isomerization and cyclization of geranyl pyrophosphate to camphane and isocamphane monoterpenes.

The conversion of geranyl pyrophosphate to (+)-bornyl pyrophosphate and (+)-camphene is considered to proceed by the initial isomerization of the substrate to (-)-(3R)-linalyl pyrophosphate and the subsequent cyclization of this bound intermediate. In the case of (-)-bornyl pyrophosphate and (-)-camphene, isomerization of the substrate to the (+)-(3S)-linalyl intermediate precedes cyclization. The geranyl and linalyl precursors were shown to be mutually competitive substrates (inhibitors) of the relevant cyclization enzymes isolated from Salvia officinalis (sage) and Tanacetum vulgare (tansy) by the mixed substrate analysis method, demonstrating that isomerization and cyclization take place at the same active site. Incubation of partially purified enzyme preparations with (3R)-[1Z-3H]linalyl pyrophosphate plus [1-14C]geranyl pyrophosphate gave rise to double-labeled (+)-bornyl pyrophosphate and (+)-camphene, whereas incubation of enzyme preparations catalyzing the antipodal cyclizations with (3S)-[1Z-3H]-linalyl pyrophosphate plus [1-14C]geranyl pyrophosphate yielded double-labeled (-)-bornyl pyrophosphate and (-)-camphene. Each product was then transformed to the corresponding (+)- or (-)-camphor without change in the 3H:14C isotope ratio, and the location of the tritium label was deduced in each case by stereoselective, base-catalyzed exchange of the exo-alpha-hydrogen of the derived ketone. The finding that the 1Z-3H of the linalyl precursor was positioned at the endo-alpha-hydrogen of the corresponding camphor in all cases, coupled to the previously demonstrated retention of configuration at C1 of the geranyl substrate in these transformations, confirmed the syn-isomerization of geranyl pyrophosphate to linalyl pyrophosphate and the cyclization of the latter via the anti,endo- conformer. These relative stereochemical elements, in combination with the observed enantiospecificities of the enzymes for the linalyl intermediates, allows definition of the overall absolute stereochemistry of the coupled isomerization and cyclization of geranyl pyrophosphate to the antipodal camphane (bornane) and isocamphane monoterpenoids.

Acyclic Monoterpenes↗
PubMed2006

Self-motion of a camphanic acid disk on water with different types of surfactants.

Control of the self-motion of a camphanic acid disk on water was investigated upon the addition of different kinds of surfactants (Triton X-100 and Brij58 as neutral surfactants, cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, and sodium dodecyl sulfate (SDS) as an anionic surfactant) to the water phase. With an increase in the concentration of surfactant, continuous motion changed to no motion via intermittent motion (repetition between motion and rest), and the concentration regions of these motions were different among these surfactants. Although the concentration regions of these motions were determined by the surface tension for neutral surfactants, they were different than those for CTAB and SDS. These characteristics of self-motion are discussed in relation to the surface tension, depending on the concentration of individual surfactants, and the hydrophilic effect of the surfactants.

Bridged-Ring Compounds↗
PubMed1988

Structure and absolute configuration of (Z)-(+)-2-bromo-2-cycloundecenyl camphanate.

C21H31BrO4, Mr = 427.38, monoclinic, P2(1), a = 8.050 (1), b = 12.703 (3), c = 10.658 (1) A, beta = 102.56 (2) degrees, V = 1063.80 A3, Z = 2, Dx = 1.334 g cm-3, lambda(Cu K alpha) = 1.5418 A, mu = 28.09 cm-1, experimental temperature 296 K. F(000) = 448, R = 0.045 for 2015 unique reflections with I greater than or equal to sigma(I). The conformation of the 11-membered ring in this compound and its absolute configuration (1R) have been determined.

Camphanes↗
PubMed2004

Syntheses, structures and antimicrobial activities of water-soluble silver(I)-oxygen bonding complexes with chiral and racemic camphanic acid (Hca) ligands.

Water-soluble, relatively light-stable, chiral and achiral silver(I) complexes [[Ag(2)(ca)(2)]](n) and [[Ag(2)(ca)(2)(Hca)(2)]](n)(R- and S-Hca =(1R,4S)- and (1S,4R)-4,7,7-trimethyl-3-oxo-2-oxabicyclo[2.2.1]heptane-1-carboxylic acid, respectively) prepared from the reaction of Ag(2)O with chiral and racemic Hca in 1:2 and 1:4 molar ratios were characterized by elemental analysis, TG/DTA, FTIR, and solution ((1)H, (13)C and (109)Ag) and solid-state ((13)C) NMR spectroscopy. Crystallography revealed that unique 2(1) helical polymer and zigzag structures were formed on self-assembly of the dimeric units in the crystals of [[Ag(2)(S-ca)(2)]](n) and three [[Ag(2)(ca)(2)(Hca)(2)]](n). In the crystal of [[Ag(2)(S-ca)(2)]](n) two 2(1) helices and a loop were observed in the stair-like polymer structure, whereas zigzag and a loop were seen in the crystals of three [[Ag(2)(ca)(2)(Hca)(2)]](n). Carbon NMR spectra in the solid state and in D(2)O indicated that these polymeric structures were loosely bound and fast ligand-exchange reactions took place in aqueous solution. The complexes, [[Ag(2)(ca)(2)]](n) and [[Ag(2)(ca)(2)(Hca)(2)]](n), showed a wide spectrum of effective antimicrobial activity as anticipated for weak silver(i)-O bonding complexes. Similar antimicrobial activity of [[Ag(2)(ca)(2)]](n) and [[Ag(2)(ca)(2)(Hca)(2)]](n) against selected microorganisms suggested that ligand exchangeability played an important role as well as the coordination geometry of the silver(i) ion.

Anti-Bacterial Agents↗
PubMed1989

Structure and absolute configuration of (E)-(-)-2-cyclododecenyl camphanate.

C22H34O4, Mr = 362.51, monoclinic, P2(1), a = 7.371 (1), b = 10.571 (1), c = 13.538 (2) A, beta = 90.36 (1) degree, V = 1054.84 A3, Z = 2, Dx = 1.141 Mg m-3, lambda(Cu K alpha) = 1.5418 A, mu = 0.577 mm-1, F(000) = 396, T = 296 K, R = 0.057 for 1550 unique reflections with I greater than or equal to sigma(I). The crystal conformation of the 12-membered ring in the title compound and its absolute configuration (1R) have been determined. The ring adopts a conformation with a necessarily approximate twofold axis in the crystal but it appears to be highly flexible.

Chemical Phenomena↗