Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PROPANEDIOLS”

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 1,063 records · Page 59Linked to original sources
PubMed2006

Catalytic asymmetric dihydroxylation of 1-substituted-1-ferrocenylethenes: an enantioselective entry to chiral tertiary ferrocenylcarbinols and ferrocenylalkylamines.

The Sharpless asymmetric dihydroxylation (AD) of 1-substituted-1-ferrocenylethenes takes place with good yields and with moderate to good enantioselectivities. The resulting 1-substituted-1-ferrocenyl-1,2-ethanediols are the first alpha-chiral tertiary ferrocenylcarbinols that have been prepared in optically active form. Their absolute configuration, ascertained by Induced Circular Dichroism (ICD), shows that in all cases the ferrocenyl moiety has the highest affinity for the SW binding pocket of the AD ligands. Depending upon the reaction conditions, significant racemization takes place during a side-chain azide nucleophilic substitution on 2-ferrocenyl-1,2-propanediol.

Amines↗
PubMed1996

Synthesis, Conformational Studies, X-ray Structures, and Complexation Properties of Semirigid Macrocyclic Phosphonamides.

The semirigid phosphonamide ligands 1-5 have been synthesized from the macrocyclic precursors 6-9 by reaction with 1,3-propanediol ditosylate or 1,2-dichloroethane. For the thiophosphoryl compounds 1 and 2, and the phosphoryl derivative 5, the reactions were carried out in biphasic aqueous NaOH solutions. The phosphoryl derivatives 3 and 4 were better obtained from NaH in anhydrous tetrahydrofuran. The conformations of the hosts in solution were deduced from low-temperature NMR and NOE difference experiments. Conformational equilibria between exo and endo forms are observed for the 18-membered macrocycles 1 and 3. The exo conformer predominates in solution for the 21-membered macrocycle 2, whereas 4 exists as rapidly exchanging conformers. The X-ray crystal structures of macrocycles 1, 2, and 5 have been determined as well as the complexes 1.Hg(SCN)(2) and 5.LiNO(3). In the Hg(2+) complex the metal ion is located out of the macrocyclic cavity and is coordinated to the thiophosphoryl unit. In 5.LiNO(3)()()the Li(+) cation is located inside the macrocyclic cavity and is coordinated to a tetrahedral array of oxygen donors. Free energies of complexation (DeltaG degrees ) of the phosphorylated ligands 3-5 with alkali metal and ammonium cations were determined in CHCl(3) saturated with H(2)O by picrate extraction experiments. The -DeltaG degrees values are greatest for 4 complexing K(+) and NH(4)(+) (7.3 and 8.0 kcal/mol, respectively). The relationships between structure and binding are discussed.

Journal Article↗
PubMed1997

Superacid-Catalyzed Reductive Friedel-Crafts Reaction of Arenes Using Arenecarbaldehyde Acetals.

Reaction of 2-aryl-1,3-dioxane with arenes in the presence of a catalytic amount of trifluoromethanesulfonic acid gave the corresponding diarylmethanes in good to excellent yields. The acid-catalyzed Friedel-Crafts benzylation of arenes could altenatively be carried out using arenecarbaldehyde and 1,3-propanediol. The reaction was assumed to proceed through a redox process involving hydride shift from the cyclic acetal moiety to the benzylic carbon. The hydride shift was confirmed by the reaction with 5-ethyl-2-phenyl-4,4,6,6-tetradeuterio-1,3-dioxane, wherein more than 90% deuterium was incorporated into the benzylic carbon of the diphenylmethane. Diphenylmethyl ether Ph(2)CHOCH(2)CH(2)CH(2)OH also reacted with benzene to afford diphenylmethane under the same reaction conditions, suggesting that the ether should be the plausible intermediate that underwent the hydride shift.

Journal Article↗
PubMed1997

Preparation of Optically Active Tertiary Alcohols by Enzymatic Methods. Application to the Synthesis of Drugs and Natural Products.

By the catalysis of AK or porcine pancreas lipases, 3-iodo-2-phenyl-1,2-propanediol, 1-(hydroxymethyl)-1-phenyloxirane, 2-(iodomethyl)-4-phenyl-3-butyne-1,2-diol, 2-(iodomethyl)-4-(trimethylsilyl)-3-butyne-1,2-diol, and 5,5-dimethyl-2-(iodomethyl)-3-hexyne-1,2-diol were resolved in very high enantioselectivities (E >/= 153). The obtained enantiomerically pure or optically enriched compounds, containing an iodo atom, an oxirane moiety, or an alkynyl group, are versatile building blocks for the synthesis of chiral azido diols, sulfanyl diols, cyano diols, the side chain of a vitamin D(3) metabolite, the omega-chain of a prostaglandin analog, and an aggregation pheromone (1S,5R)-(-)-frontalin. Models based on the consideration of the importance of size, distance, and electron effect are proposed to interpret the observed stereospecificity in the enzymatic reactions. Thus, the lipase-catalyzed reactions of 1,1-disubstituted 1,2-diols occurred efficiently at the primary hydroxyl groups while the enantioselectivity was controlled by the tertiary carbinyl centers.

Journal Article↗
PubMed1998

High Catalytic Activity of Chiral Amino Alcohol Ligands Anchored to Polystyrene Resins.

Enantiomerically pure (2S,3S)-2,3-epoxy-3-phenylpropanol (3) has been anchored to Merrifield resins with different degrees of cross-linking and functionalization. The resulting epoxy-functionalized resins 4 have been submitted to completely regioselective (C-3 attack) and stereospecific ring-opening with secondary amines [piperidine (a), N-methylpiperazine (b), and cis-2,6-dimethylpiperidine (c)] in the presence of lithium perchlorate to afford (2R,3R)-3-(dialkylamino)-2-hydroxy-3-phenylpropoxy resin ethers 5a-c. The progress of these two processes has been monitored by (13)C gel-phase NMR spectroscopy. Polymer-supported amino alcohols 5a-c have been evaluated as catalytic ligands in the enantioselective addition of diethylzinc to benzaldehyde, best results being obtained with the cis-2,6-dimethylpiperidine containing ligand 5c. Analogously, (2R,3R)-3-(cis-2,6-dimethylpiperidino)-3-phenyl-1,2-propanediol (11) has been anchored to a 2-chlorotrityl chloride resin (Barlos resin) in dichloromethane in the presence of diisopropylethylamine, and the anchoring process has been also monitored by (13)C gel-phase NMR spectroscopy. The resulting resin 12 has subsequently been used as a chiral ligand in the catalytic addition at 0 degrees C of diethylzinc to a family of fourteen representative aromatic and aliphatic aldehydes 8a-n, to afford the corresponding (S)-1-substituted 1-propanols 10a-n with a mean enantiomeric excess of 92%.

Journal Article↗
PubMed2000

Synthesis and characterization of 5-substituted 1,3-diazacyclohexane derivatives

Three synthetic routes to 5-substituted 1,3-diazacyclohexane derivatives 1 are reported. The first method involves treatment of 1, 3-diaminopropan-2-ol 2 with paraformaldehyde to yield 5-hydroxy-1, 3-diazacyclohexane 3. A second method is based on the condensation of 2-bromo-2-nitro-1,3-propanediol with tert-butylamine and formaldehyde to yield 1,3-di-tert-butyl-5-bromo-5-nitro-1, 3-diazacyclohexane 22. The third method relies on the cycloalkylation of methylenebisacetamide with 3-chloro-2-chloromethyl-2-propene to provide 5-exomethylene-1, 3-diacetyl-1,3-diazacyclohexane 28. Functional group manipulations of 3, 22, and 28 provide a number of novel 1,3-diazacyclohexanes functionalized at the 5-position.

Journal Article↗
PubMed2000

New synthetic approaches to polycyclic aromatic hydrocarbons and their carcinogenic oxidized metabolites: derivatives of benzo[s]picene, benzo[rst]pentaphene, and dibenzo[b,def]chrysene.

A new synthetic approach to polycyclic aromatic compounds is described that entails in the key steps double Suzuki coupling of PAH bisboronic acid derivatives with o-bromoaryl aldehydes to furnish aryl dialdehydes that are converted to larger polycyclic aromatic ring systems by either (a) conversion to diolefins by Wittig reaction followed by photocyclization or (b) reductive cyclization with triflic acid and 1,3-propanediol. This synthetic method provides convenient access to as many as three different polycyclic aromatic ring systems from a single Suzuki coupled intermediate. It was utilized to synthesize substituted derivatives of benzo[s]picene, benzo[rst]pentaphene, dibenzo[b,def]chrysene, and 13,14-dihydro-benz[g]indeno[2,1-a]fluorene, as well as the putative carcinogenic bisdihydrodiol metabolites of benzo[s]picene, benzo[rst]pentaphene, and dibenzo[b,def]chrysene.

Benzopyrenes↗
PubMed2006

Conformational change of poly(ethylene glycol) near the critical point of isobutyric acid + water.

In solutions of isobutyric acid + water, poly(ethylene glycol) (PEG) can assume a helical conformation. [Alessi, M. L.; Norman, A. I.; Knowlton, S. E.; Ho, D. L.; Greer, S. C. Macromolecules 2005, 35, 9333-9340.] Here we report new measurements of the kinematic viscosity, nu, as a function of temperature for a solution of isobutyric acid + water at the critical composition, to which PEG (number average molecular weight = 1.01 x10(3) g/mol) was added at a concentration of 6.01 mg/mL. The data show that nu decreases near the critical point, with a maximum in nu at about 0.05 degrees C above the critical temperature, Tc. We interpret this change in nu in terms of a change in conformation of the polymer from helix to coil. This interpretation is supported by polarimetry measurements on the same mixture doped with (S)-(+)-1,2-propanediol, which indicates the loss of helicity near Tc and also a second helix-to-coil transition at about 60 degrees C.

Journal Article↗
PubMed2004

The dominant role of solvent in the sequestering of bile salts by hydrophobic cationic polymeric resins.

The binding behavior of sodium cholate, a trihydroxy hydrophobic bile salt, by a polyacrylamide resin with N,N,N-trimethylammonium dodecyl chloride (QPDA12) pendant group was determined with varying buffer conditions and in the presence of 1,2-propanediol as a solvent perturbant. Binding constants extracted from the fit of the binding isotherms to the Langmuir equation were obtained at several temperatures. The temperature dependence of the binding behavior indicated that binding, in comparison with that of the dihydroxy chenodeoxycholate, was weaker due to a smaller positive entropic change, despite a lowered enthalpic barrier. Enthalpy-entropy compensation with a compensation temperature of 285-290 K, characteristic of processes involving water, was found to encompass both the cholate and chenodeoxycholate data under a wide variety of conditions. Previous studies with sodium chenodeoxycholate determined that loss of hydrophobic hydration within the resin dominated the thermodynamics of the binding process, but the observations with sodium cholate revealed that solvent liberation about the bile salt is also a contributor.

Acrylic Resins↗
PubMed2005

Electrostatics of PEGylated micelles and liposomes containing charged and neutral lipopolymers.

The electrostatics of large unilamellar vesicles (LUVs) of various lipid compositions were determined and correlated with steric stabilization. The compositional variables studied include (a) degree of saturation, comparing the unsaturated egg phosphatidylcholine (EPC) and the fully hydrogenated soy phosphatidylcholine (HSPC) as liposome-forming lipids; (b) the effect of 40 mol % cholesterol; (c) the effect of mole % of three methyl poly(ethylene glycol) (mPEG)-lipids (the negatively charged mPEG-distearoyl phosphoethanolamine (DSPE) and two uncharged lipopolymers, mPEG-distearoyl glycerol (DSG) and mPEG-oxycarbonyl-3-amino-1,2-propanediol distearoyl ester (DS)); and (d) the negatively charged phosphatidyl glycerol (PG). The lipid phases were as follows: liquid disordered (LD) for the EPC-containing LUV, solid ordered (SO) for the HSPC-containing LUV, and liquid ordered (LO) for either of those LUV with the addition of 40 mol % cholesterol. The LUV zeta potential and electrical surface potential (psi(0)) were determined. It was found that progressive addition of mPEG(2k)-DSPE to liposomes increases negative surface potential and reduces surface pH to a similar extent as the addition of PG. However, due to the "hidden charge effect", zeta potential was more negative for liposomes containing PG than for those containing mPEG(2k)-DSPE. Replacing mPEG-DSPE with mPEG(2k)-DS or mPEG-DSG had no effect on surface pH and surface potential, and zeta potential was approximately zero. Addition of low concentrations of cationic peptides (protamine sulfate and melittin) to PG- or mPEG-DSPE-containing liposomes neutralized the liposome negative surface potential to a similar extent. However, only in liposomes containing PG, did liposome aggregation occur. Replacing the negatively charged lipopolymer mPEG-DSPE with the neutral lipopolymers mPEG-DS or mPEG-DSG eliminates or reduces such interactions. The relevance of this effect to the liposome performance in vivo is discussed.

Hydrogen-Ion Concentration↗
PubMed2005

Acetate- and thiol-capped monodisperse ruthenium nanoparticles: XPS, XAS, and HRTEM studies.

Monodisperse ruthenium nanoparticles were prepared by reduction of RuCl3 in 1,2-propanediol. The mean particle size was controlled by appropriate choice of the reduction temperature and the acetate ion concentration. Colloidal solutions in toluene were obtained by coating the metal particles with dodecanethiol. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XANES and EXAFS for the Ru K-absorption edge) were performed on particles of two different diameters, 2 and 4 nm, and in different environments, polyol/acetate or thiol. For particles stored in polyol/acetate XPS studies revealed superficial oxidation limited to one monolayer and a surface coating containing mostly acetate ions. Analysis of the EXAFS spectra showed both oxygen and ruthenium atoms around the ruthenium atoms with a Ru-Ru coordination number N smaller than the bulk value, as expected for fine particles. In the case of 2 nm acetate-capped particles N is consistent with particles made up of a metallic core and an oxidized monolayer. For 2 nm thiol-coated particles, a Ru-S bond was evidenced by XPS and XAS. For the 4 nm particles XANES and XPS studies showed that most of the ruthenium atoms are in the zerovalent state. Nevertheless, in both cases, when capped with thiol, the Ru-Ru coordination number inferred from EXAFS is much smaller than for particles of the same size stored in polyol. This is attributed to a structural disorganization of the particles by thiol chemisorption. HRTEM studies confirm the marked dependence of the structural properties of the ruthenium particles on their chemical environment; they show the acetate-coated particles to be single crystals, whereas the thiol-coated particles appear to be polycrystalline.

Journal Article↗
PubMed1998

Identification and synthesis of novel chlorinated p-anisylpropanoid metabolites from bjerkandera species

Analysis of the EtOAc extracts from the culture medium of Bjerkandera sp. BOS55 and B. fumosa revealed the presence of two novel chlorinated metabolites. Their structures were unambiguously established as erythro-1-(3',5'-dichloro-4'-methoxyphenyl)-1, 2-propanediol (2) and 1-(3'-chloro-4'-methoxyphenyl)-3-hydroxy-1-propanone (3) through synthesis of authentic samples and comparison of retention times and mass spectral data. The production of trametol (1) by Bjerkandera sp. BOS55 was also a new finding.

Journal Article↗
PubMed2000

Stereoselective synthesis of optically active alpha-hydroxy ketones and anti-1,2-diols via asymmetric transfer hydrogenation of unsymmetrically substituted 1,2-diketones.

[reaction: see text] A well-defined chiral Ru catalyst RuCl(N-(p-toluenesulfonyl)-1, 2-diphenylethylenediamine)(eta(6)-arene) effectively promotes asymmetric transfer hydrogenation of 1-aryl-1,2-propanedione with HCOOH/N(C(2)H(5))(3), leading preferentially to optically active 1-aryl-2-hydroxy-1-propanone with up to 99% ee and 89% yield at 10 degrees C. The reaction at 40 degrees C gives anti-1-aryl-1, 2-propanediol with up to 95% ee and 78% yield. This is a highly efficient procedure for the synthesis of optically active anti-diols.

Catalysis↗
PubMed2000

Asymmetric desymmetrization of 2,2',6,6'-tetrahydroxybiphenyl through annulation with enantiomerically pure bis(mesylate)

[formula: see text] 2,2',6,6'-Tetrahydroxybiphenyl undergoes a facile annulation reaction with bis(mesylate) derived from (S)-1,2-propanediol in the presence of Cs2CO3 to give the corresponding asymmetric desymmetrization product of S axial chirality with exclusive diastereoselectivity. The desymmetrization product can be utilized as a versatile chiral building block in asymmetric synthesis of axially chiral 6,6'-disubstituted 2,2'-biphenyldiols.

Journal Article↗
PubMed2001

Subtilisin-catalyzed synthesis of amino acid and peptide esters. Application in a two-step enzymatic ligation strategy.

We describe an efficient enzymatic approach to the synthesis of amino acid and peptide esters. The serine protease subtilisin Carlsberg (EC 3.4.21.62) was found to efficiently catalyze the specific formation of C(alpha)-carboxyl 3-hydroxypropyl or 4-hydroxybutyl esters of certain Boc-amino acids and peptides in high-content 1,3-propanediol or 1,4-butanediol solution, with substrate specificity parallel to that of the normal hydrolytic reaction. This approach can be coupled with kinetic-control reverse proteolysis in a two-step enzymatic peptide ligation scheme. [reaction: see text]

Amino Acids↗
PubMed2002

Synthesis of lipophilic aldehydes and study of their inhibition effect on human digestive lipases.

[reaction: see text] Novel inhibitors of human digestive lipases, aldehyde dialkyl and alkyl-acyl glycerol analogues, were developed. The inhibitors were prepared starting from 3-(benzyloxy)-1,2-propanediol. The inhibition of human pancreatic and gastric lipases by the aldehyde derivatives was studied using the monolayer technique. (1R)-1-[(Dodecyloxy)methyl]-4-oxobutyl decanoate caused a 50% decrease in HPL and HGL activities at 0.100 and 0.053 molar fractions, respectively.

Aldehydes↗
PubMed2003

Enantioselective total synthesis of (+)-leucascandrolide A macrolactone.

[reaction: see text] The enantioselective synthesis of the (+)-leucascandrolide A macrolactone has been achieved in 20 linear steps from 1,3-propanediol. The key steps in the synthesis are a reductive cleavage of bicyclic ketal 5 to establish the C15 stereogenic center and a diastereoselective aldol of the boron enolate of methyl ketone 3 to aldehyde 4 in preparation for a heteroconjugate addition for the introduction of the C3 stereocenter.

Aldehydes↗