Diol Derivatives Research Articles

Rapid Access to an Orthogonally Protected Lewis X Derivative: An Important Building Block for Synthesis of Lewis Antigens

Abstract A novel Lewis X derivative of 1 with an orthogonal set of protecting groups was systematically prepared. Efficient use of the protecting groups for the amino and the hydroxy groups in lactosamine enabled formation of the diol derivative at C3 and C2′. Glycosidation of 1-thio-l-fucoside donor with the diol derivative progressed preferably at the C3 hydroxy group, resulting in prior production of 1. Compound 1 is a key building block toward easy assemblies of Lewis X-related carbohydrate epitopes.

Ring of Rings

Chemistry The abstract prospect of using a circle to derive a square has intrigued scholars of geometry for centuries. Segawa et al. have now used a square to derive a circle. The arena in this case was chemistry, rather than mathematics, and the task at hand was to assemble a molecular ring composed in turn of 12 benzene rings, linked to one another at the diametrically opposed 1 and 4 positions. Previous efforts had yielded small quantities of this [12]cycloparaphenylene in a mixture of variously sized relatives bearing 9 through 18 benzenes. The key to a more efficient route was a building block linking two benzene rings at an approximate right angle through an intervening cyclohexane diol derivative. By thoroughly optimizing a catalytic nickel system, the authors succeeded in linking four such building blocks in a single reaction medium to form a square with the cyclohexane rings at the corners and two benzenes along each edge. Dehydration/aromatization of the corner rings then honed the square into the circular targeted product in sufficient yield to afford a crystal structure. Angew. Chem. Int. Ed. 50 , 10.1002/anie.201007232 (2011).

Synthesis of optically active derivatives of bicyclic chiral diols with C2 symmetry

This paper reports efficient procedures for the preparation of optically active dibromide, diazide, diamine, and unsaturated diesters derived from a chiral bicyclic diol with C2 symmetry namely (11R,12R)-9,10-dihydro-9,10-ethaneanthracene-11,12-dimethanol 3. Esterification of 3 with saturated and unsaturated carboxylic acids and acids chlorides leads to the corresponding normal-, olefinic- and acetylenic diesters in average yields of 81%. Also more efficient techniques for the preparation of starting diol 3 in higher yields as well as for a very simple separation of DCU (N,N′-dicyclohexylurea) from reactions carried out following the DCC/DMAP method are described.

Photodegradation of insecticide metofluthrin on soil, clay minerals and glass surfaces

Photodegradation of pyrethroid insecticide metofluthrin (I) [2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (EZ)-(1R,3R)-2,2-dimethyl-3-(prop-1-enyl)cyclopropanecarboxylate] on soil, clay minerals, and glass surfaces was examined using a xenon arc lamp (>290 nm). I was rapidly photodegraded via oxidation of the double bond at the prop-1-enyl moiety and cleavage of the ester linkage followed by mineralization to carbon dioxide, while photo-isomerization to other isomers was a minor route. The major photodegradates having an intact ester linkage were the caronaldehyde and carboxylic acid derivatives formed via 1,2,4-trioxolane (ozonide) and the diol derivatives formed via epoxide, which strongly suggested the involvement of ozone and hydrogen peroxide as the active oxygen species.

An achiral manganese salen catalyst encapsulated in a peptidic phosphonate homochiral solid for the enantioselective formation of diols by consecutive epoxidation and hydration reactions

An insoluble, porous, amorphous, homochiral material based on a polypeptide titanium-phosphonate scaffold with an encapsulated achiral Mn(III)-salen was prepared and characterized. Consecutive epoxidation and hydration of styrene and its derivatives by aqueous hypochlorite in THF showed the highly enantioselective (>99%) formation of styrene diol derivatives.

Identification of 20(S)-Protopanaxadiol Metabolites in Human Liver Microsomes and Human Hepatocytes

20(S)-Protopanaxadiol (PPD, 1) is one of the aglycones of the ginsenosides and has a wide range of pharmacological activities. At present, PPD has progressed to early clinical trials as an antidepressant. In this study, its fate in mixed human liver microsomes (HLMs) and human hepatocytes was examined for the first time. By using liquid chromatography-electrospray ionization ion trap mass spectrometry, 24 metabolites were found. Four metabolites were isolated, and their structures were elucidated as (20S,24S)-epoxydammarane-3,12,25-triol (2), (20S,24R)-epoxydammarane-3,12,25-triol (3), (20S,24S)-epoxydammarane-12,25-diol-3-one (4), and (20S,24R)-epoxydammarane-12,25-diol-3-one (5) based on a detailed analysis of their spectroscopic data. The predominant metabolic pathway of PPD observed was the oxidation of the 24,25-double bond to yield 24,25-epoxides, followed by hydrolysis and rearrangement to form the corresponding 24,25-vicinal diol derivatives (M6) and the 20,24-oxide form (2 and 3). Further sequential metabolites (M2-M5) were also detected through the hydroxylation and dehydrogenation of 2 and 3. All of the phase I metabolites except for M1-1 possess a hydroxyl group at C-25 of the side chain, which was newly formed by biotransformation. Two glucuronide conjugates (M7) attributed to 2 and 3 were detected in human hepatocyte incubations, and their conjugation sites were tentatively assigned to the 25-hydroxyl group. The findings of this study strongly suggested that the formation of the 25-hydroxyl group is very important for the elimination of PPD.

Chiral Amino Diol Derivatives as New Modular Organocatalysts for the Enantioselective α‐Chlorination of Cyclic β‐Keto Esters

AbstractHighly modular chiral amino diol derivatives have been used as organocatalysts in the enantioselective α‐chlorination of cyclic β‐keto esters. Optimization of the catalyst structure and the reaction conditions has allowed the synthesis of optically active α‐chlorinated products with high enantioselectivities (up to 96% ee) using inexpensive commercially available N‐chlorosuccinimide (NCS) as the chlorine source under mild conditions.

An asymmetric route to 2,3-epoxy-syn-1,4-cyclohexane diol derivatives using ring closing metathesis (RCM)

An asymmetric route for the synthesis of highly functionalized 2,3-epoxy-syn-1,4-cyclohexane diol derivatives present in some polyketide natural products has been developed. The key step involves RCM of an appropriately constructed 1,7-dienol derived from D-mannitol to cyclohexane-1,4-diol followed by its stereoselective epoxidation.

Biodegradable Main-Chain Phosphate-Caged Fluorescein Polymers for the Evaluation of Enzymatic Activity

We describe here the biodegradable polymers consisted of the tandemly linked phosphate-caged fluorescein in the main chains. The caged-fluorescein monomer with the phosphoramidite groups at both hydroxyl groups was synthesized, and the polycondensations were executed in the presence of the diol derivatives which were promised to be the reactivity-tunable linker. After oxidation and the alkaline treatment for the deprotection, less-emissive polymeric products were obtained. The resulting polymers can release fluorescein by the digestion with alkaline phosphatase. We demonstrated that the enzymatic activity of the cell lysate can be quantified from the increase of the magnitude of fluorescence emission with the synthetic polymers.

Asymmetric Synthesis of Bicyclic Diol Derivatives through Metal and Enzyme Catalysis: Application to the Formal Synthesis of Sertraline

Enzyme- and ruthenium-catalyzed dynamic kinetic asymmetric transformation (DYKAT) of bicyclic diols to their diacetates was highly enantio- and diastereoselective to give the corresponding diacetates in high yield with high enantioselectivity (99.9 % ee). The enantiomerically pure diols are accessible by simple hydrolysis (NaOH, MeOH), but an alternative enzyme-catalyzed ester cleavage was also used to give the trans-diol (R,R)-1 b in extremely high diastereomeric purity (trans/cis=99.9:0.1, >99.9 % ee). It was demonstrated that the diols can be selectively oxidized to the ketoalcohols in a ruthenium-catalyzed Oppenauer-type reaction. A formal enantioselective synthesis of sertraline from a simple racemic cis/trans diol 1 b was demonstrated.

Locked chromophores as CD and NMR probes for the helical conformation of tetraamidic macrocycles

A series of tetraamidic homochiral macrocycles have been built convergently upon the introduction in the covalent scaffold of two 1,1'-binaphthyl-2,2'-diol derivatives, joined by aromatic spacers of differing shapes and rigidity (p-phenyl, 4,4'-biphenyl, 3,3'-biphenyl) through aromatic amide functionalities, perfectly positioned to intramolecularly hydrogen bond the naphtholic oxygen acceptors of the binaphthyl units, in order to effectively lock the central chromophores in spatial proximity. The combination of several techniques, namely NMR and CD spectroscopies, and computational modeling, allows for a clear depiction of the structure and conformation of the macrocycles in solution. In the case of the shape "unstable" 3,3'-biphenyl spacer, the preferred conformation of a "wrapped" form in a relatively polar (EtOH) solvent is clearly signalled by CD spectroscopy by analyzing the changes in the shape of the induced CD signal deriving from the central, achiral chromophore absorption band. The rigid, covalent scaffold in which the two central 3,3'-biphenyl spacers are embedded raises the energetic barrier for the rotation around the aryl-aryl bonds of the spacers to a value (8.0 kcal mol(-1)) much higher than the value calculated in the case of unlocked biphenyls.

Theoretical Study of the Peripheral Disulfide Bridge Substituent Effects on the Antioxidant Properties of Naphthyridine Diol Derivatives

The effect of a peripheral disulfide bridge substituent on the phenolic O-H bond dissociation energy (BDE) and the ionization potential (IP) of naphthyridine diol has been studied by density functional theory (DFT) calculation. Compared with naphthalene diol, the substituent of a peripheral disulfide bridge group is very efficient in reducing the BDE, whereas the insertion of nitrogen atoms into the naphthalenic ring only slightly changes the BDE of O-H bond but dramatically enhances the IP. It is similar with the stereoelectronic effect of the heterocyclic ring for the well-known alpha-tocopherol antioxidant and leads to a highly delocalized spin distribution. With the incorporation of these two aspects, a potential antioxidant is expected to be more active and more stable than alpha-tocopherol.

Influence of diluent compositions on the porous structure of methacrylate derivatives of aromatic diols and divinylbenzene

Synthesis and properties of the new aromatic tetrafunctional methacrylate monomer 2,7-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene are presented. This monomer was applied for the synthesis of porous microspheres. It was copolymerized with divinylbenzene in the presence of pore-forming diluents, decan-1-ol and toluene. Influence of diluents composition on their porous structures was studied. Porous structures of the obtained microspheres in dry (from nitrogen adsorption–desorption measurements) and swollen (the inverse size exclusion chromatography method) states were compared with those synthesized from isomeric 2,3-(2-hydroxy-3-methacryloyloxypropoxy)-naphthalene and divinylbenzene.

Direct Construction of 1,3-Diaxial Diol Derivatives by C−H Hydroxylation

Direct hydroxylation of tertiary C-H bonds for construction of 1,3-diaxial diol derivatives was achieved by devising a new detachable dioxirane precursor containing a trifluoromethyl ketone moiety and ethylene tether. Oxone treatment of the ketones led to the corresponding dioxiranes, enabling hydroxy group installment into cyclohexane and steroid derivatives in a regio- and stereoselective manner through intramolecular oxygen insertion.

Synthesis of Two New Hemisynthetic Diterpenylhydroquinones from Natural Ent-Labdanes

The synthesis and structural determination of two new diterpenylhydroquinones: 2β-acetoxy-15-phenyl-(22,25-dihydroxy)-ent-labda-8(17),13(E)-diene (1) and 2β-hydroxy-15-phenyl-(22,25-dihydroxy)-ent-labda-8(17),13(E)-diene is reported (2). These compounds were obtained by coupling via Electrophilic Aromatic Substitution (EAS) of 1,4-hydroquinone with primary or tertiary allyl alcohol derivatives of the natural ent-labdanes 3 and 4. With this new method, the best results were observed when mixtures of the primary alcohol derivatives 5-6 (26% yield of compound 1) and diol derivatives 9-10 (28% yield of compound 2) were used.

An ab initio study of 5,6-disubstituted 1,3-cyclohexadienes

A computational study of 1,3-cyclohexadiene and some 5,6-disubstituted derivatives is presented. We examine the geometry, vibrational frequencies, and barrier to inversion of 1,3-cyclohexadiene, and discuss how these change with level of theory from HF to CCSD(T). We then examine these quantities at the HF and MP2 levels for various derivatives such as the alcohol, diol, dimethoxy, and a series of cyclic diol derivatives. The barrier to ring inversion correlated with the reported rate of Diels–Alder reaction, but not to the syn–anti ratio. Analysis of the photoelectron spectrum of the dienes offers no insight towards understanding the syn/anti ratio. The C s -symmetric transition structures to Diels–Alder reaction are similar for the reaction of 1,3-cyclohexadiene with both ethene and ethyne.

Synthesis and 13C NMR Spectroscopy of Model Compounds for the Microstructure Analysis of Poly(Vinyl Glycoside)s

AbstractA series of glycosylated diol and triol derivatives was synthesized in order to serve as model compounds for the analysis of the stereochemistry, regiochemistry, and defect structures of poly(vinyl glycoside)s. 13C NMR spectroscopic analysis of these compounds revealed that the attached chiral carbohydrate substituents induced a strong correlation of the chemical shifts of both the anomeric C and the α‐C atom of the aglycon with the absolute configuration of the latter. The influence of the stereoconfiguration of β‐ and γ‐C atoms as well as the regiochemistry of the aglycon on the chemical shifts of the α‐C and the anomeric C atom was also investigated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Hydrogen-bonded layered structures in two bis(tert-butyldimethylsilyloxy)-substituted cyclic diol derivatives

2,6-Bis(tert-butyldimethylsilyloxy)-9-oxabicyclo[3.3.1]nonane-3,7-diol, C(20)H(42)O(5)Si(2), (I), and 4,8-bis(tert-butyldimethylsilyloxy)-2,6-dioxatricyclo[3.3.1(3,7)]decane-1,3-diol, C(20)H(40)O(6)Si(2), (II), form layered structures that differ in the way the molecules are connected within each layer. The endocyclic O atom common to both structures plays an active role in the hydrogen-bonding network, whereas the second oxygen bridge in (II) does not participate in any interaction. This work reports the first structural analysis of two bis(tert-butyldimethylsilyloxy)-substituted cyclic diol derivatives and provides insight into the influence of small changes in the molecular structure on the supramolecular aggregation. The unbalanced hydrogen-bond acceptor/donor ratio, greater in (II) than in (I), does not result in the inclusion of water molecules in the structure.

Synthesis and mesophase behaviour of rigid rod‐like phenylthiophene‐based amphiphilic diol derivatives

Novel amphiphilic block molecules consisting of a rigid 2‐phenylthiophene or 5‐phenylbithienyl core, with a polar glycerol group attached to the phenyl ring and one or two alkyl chains attached to the thiophene ring on the other side, have been synthesised by using Ni(0) and Pd(0) catalyzed coupling reactions as key steps. The thermotropic and solvent‐induced liquid crystalline behaviour of these compounds was investigated by polarising optical microscopy and X‐ray diffraction. The influence of the length, number and position of the alkyl chains, and the length of the rigid core, on their mesophase behaviour was investigated. Compounds with one alkyl chain in the terminal 5‐position on the thiophene ring form only smectic A phases, compounds with two adjacent alkyl chains attached in the 4‐ and 5‐positions of the thiophene ring exhibit thermotropic columnar mesophases, and those with two long alkyl chains attached to the 3‐ and 5‐positions form columnar LC phases only in the presence of water. Another compound containing the longer 5‐phenylbithienyl core unit and two alkyl chains attached in lateral positions to each of the thiophene rings is not mesogenic.

ChemInform Abstract: Partial Oxidation of Alkenylsilanes with Ozone: A Novel Stereoselective Approach to the Diol and Triol Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.