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A recently devised method for the Synthesis of 2,3-dihydro-10bH-oxazolol[2,3-a]isoquinolines from ortho-lithiated phenyloxazolinyloxiranes is being discussed.

A combination of the growth probability method and several three-dimensional (3D) nucleation simulations is used to study the formation of polymorphs, wherein the nucleus size acts as a function of the driving force for crystallization. The study has found application in a large number of fields that includes a yellow isoxazolone dye, paracetamol and L-glutamic acid, as they show dominant nucleation of their stable form at all driving forces.

The isomerization and decomposition of 1,2-benzisoxazole are analyzed behind reflected shock waves in a pressurized driver, single-pulse shock tube. The rate constants are estimated on the basis of the potential energy surfaces by using transition-state theory and are compared to the experimental results obtained by the single-pulse shock-tube method.

The formation and the reactivity of three selected sulfur-centered radicals formed from mercaptobenzoxazole, mercaptobenzimidazole and mercaptobenzothiazole toward double bonds are examined using laser LFP and quantum mechanical calculations. The polar effects are the key factors governing the addition reaction, whereas the back-fragmentation reaction is governed by enthalpy effects.

Synthesis of three regioisomers of aromatic-substituted phosphinyl-oxazolinyl-[2,2]paracyclophanes, pseudo-geminal, pseudo-ortho and ortho is conducted. It is demonstrated that all aromatic-substituted isomers relevant for use as chelating ligands for asymmetric catalysis are accessible.

The stereochemical outcome of the alkylation of a variety of phenyglycinol-derived oxazolopiperidone lactams is studied. The synthetic utility of the alkylation reactions is illustrated with the synthesis of cis and trans 3,5-disubstituted, 2,5-disubstituted and 2,3,5-trisubstituted enantiopure piperidines and the indole alkaloids 20R- and 20S-dihydrocleavamine.

The described chemistry provides entries into the halipeptin family of compounds including the naturally occurring halipeptins A and D, and their analogues. By rendering these materials available, as well as their oxazoline analogues 5d(super 3) and 6d(super 3), chemical synthesis allowed their biological evaluation in cytotoxicity and inflammation assays.

The stereoselective syntheses of beta-trifluoromethyl-beta-amino ester, beta lactams and beta-amino ketones starting from an oxazolidine derived from trifluoroacetaldehyde hemiacetal and (R)-phenylglycinol are reported. The diastereoselectivity of the reported Reformatsky and Mannich-type reactions from 2-trifluoromethyl-1,3-oxazolidines are varied.

Three sets of oligomers containing the 4-carboxy-5-methyloxazolidin-2-one (Oxd) moiety were synthesized in a study with the aim of checking whether these molecules are able to fold in ordered structures. A deeper insight into the CD spectra reveals that the secondary structure adopted by one set of oligomers is a beta-bend ribbon spiral, which is a subtype of the 3(sub 10)-helix.

Three enantiomers of cyclohexane-linked bis-oxazoline that were synthesized in one-pot reactions by using the corresponding diacids and L-phenylglycinol as starting materials and were applied in the asymmetric aziridination of chalcones were discussed. The results show that the enantioselectivity is not substituent-dependent with respect to chalcones.

A study is conducted which highlights the use of diazocarbonyl chemistry in the synthesis of oxazoles many of which are relatively complex. Successful synthesis of a range of oxazoles and indole bis-oxazoles related to diazonamide A is achieved using diazocarbonyl methodology.

A phenylglycinol-derived tripodal oxazoline with C1-symmetry (C1-PhBTO) is synthesized, and its enantioselective recognition behavior toward alpha-chiral primary organoammonium ions is studied. The C1-symmetric receptors, particularly (C1-PhBTO), interact with the guests in a 2:1 host-guest complex mode in a stark contrast to its C3-symmetric analogues as indicated by the binding studies.

A highly convergent and efficient total synthesis of the potent antitumor polyketide (-)-callystatin A is described. The synthesis required 19 steps from N-propionyl oxazolidinone and produced the desired product in 3.5% overall yield.

Macrolides have been modified to a large extent by structural and functional variants to expand their spectrum of activity and overcome resistance. Ketolides are new generation 14-membered ring macrolides derived by chemical modification of the readily available erythromycin A. We have designed and synthesized bicyclic oxazolidinone-[delta]-lactones to mimic the "left segment" periphery of ketolides. Key words: macrolide, ketolide, 50S r-RNA, segment mimetics. Des macrolides ont ete beaucoup modifies par des variations de structure et de fonction afin d'elargir leur spectre d'activite et pour vaincre la resistance. Les cetolides correspondent a une nouvelle generation de macrolides a quatorze chainons qui derivent de modifications chimiques de l'erythromycine A qui est facilement accessible. Pour imiter le segment de gauche de la peripherie des cetolides, de nouvelles [delta]-lactones bicycliques de l'oxazolidinone ont ete developpees et synthetisees. Mots cles : macrolide, cetolide, 50S r-ARN, imitation d'un segment. [Traduit par la Redaction]

Cobalt oxazoline palladacycles (COP) having acetylacetonate and hexafluroacetylacetonate ligands were prepared as catalysts for the asymmetric rearrangement of allytic trichloroacetimidates. The yields and enantioselectives in CH2Cl2 were slightly inferior to those realized with COP-Cl.

A novel hetero-pinacol-based macrocyclization cascade sequence is developed and the advanced compound bearing both of the 12-membered rings of the target module is noticed. The preliminary biological studies with intermediates and simplified analogues obtained via developed sequences are described.

A concise, enantiospecific synthesis of the antitubercular marine natural product pseudopteroxazole, which was earlier assigned the structure of pseudopteroxazole, is described using S-(-)-limonene. The synthesis helps in demonstrating the presence of a biomimetic cyclization, which provides a basis for understanding the origin of the stereochemical diversity of the pseudopterosin family and the formation of the natural diastereomeric structures.

The use of metal coordination has allowed the preparation of polycatenar oxazoline complexes that show columnar mesophases with a helical organization within the column. A significant example of a successful combination of coordination chemistry and liquid crystal self-organization processes to achieve and control supramolecular helical architectures.

The potential of iridium complexes of the N-heterocyclic carbene oxazoline ligands in asymmetric hydrogenations of arylalkenes is examined. Pressure dependence studies disclosed that many reactions performed with high conversions and optimal enantioselectivities in approximately 2h when only 1 bar of hydrogen was used.

Methylation of oxazoles at the 4 and 5 position was achieved after regioselective C-2 silyl protection. Removal of the protecting group was then accomplished under mild conditions allowing for a straightforward preparation of C-5 monosubstituted and C-4,5 disubstituted oxazoles.

A novel synthetic method for the ring closure to fused heterocyclic bicycles such as pyrrolo [1,2-c]oxazole-1-ones, oxazolo[3,4-a]indol-1-ones, pyrrolo[1,2-c]imidazoles, and imidazo[1,5-a]indoles, by a simple one step procedure is reported. It is found that the novel bicycle was formed in low yield when compound was treated with a stoichiometric amount of triethylamine or guanidine hydrochloride in refluxing acetone.

One-pot synthesis of 2-aminobenzoxazoles by using commercially available tetramethyl orthocarbonate or 1,1-dichlorodiphenoxymethane, an amine, and an optionally substituted 2-aminophenol is described. The scope of the reactions conducted under mild conditions which provided 2-aminobenzoxazoles in modest to excellent yields was examined by using a variety of amines and substituted 2-aminophenols.

Enantioselective cyclization of E- and Z-configured allylic bis-trichloroacetimidates to highly enantioenriched 2-trichloromethyl-4-vinyloxazoline in presence of cationic Pd(II) catalysts generated from chiral biphenyl diphosphine complexes or from COP-Cl is described. The process is an excellent example for olefin amination in high yield and enantioselectivity with trichloroacetimidate as the N-nucleophile to provide an easy-to-deprotect enantioenriched vinylglycinol derivative in presence of cationic palladium(II) complex.

The studies about the photoinduced reactions of the 1,2-dicarbonyl compounds phenanthrenequinone (PQ), 1-acetylisatin (IS) and benzil (BZ) with the oxazoles are discussed. Regio- and diastereoselectivity in the [2 + 2] and [4 + 4] cycloadditions based on the thermodynamic stability of the relevant triplet diradical intermediates and the conformations of these diradicals suitable for the intersystem crossing process are also discussed.

Dihydrobenzisoxazoles are prepared by the [3+2] cycloaddition of oxaziridines and arynes, where the reaction has involved a cleavage of the C-O bond of the oxaziridine. The halogen-substituted dihydrobenzisoxazoles are elaborated to more complex products by using palladium-catalyzed crossing-coupling processes.

A highly efficient and convenient strategy is described that has allowed rapid construction of unique optically active spiro[oxazoline-3,3' -oxindole]s through the organocatalyzed asymmetric synthesis of spirocyclic thiocarbamates via an aldol reaction. The evaluation of the spirooxazolines using a model of acute neuroinflammation has shown antipyretic activity and has provided an opportunity to discover new antipyretic agents.

The catalytic enantioselective [S.sub.N]2' displacement of (Z)-allylic trichloroacetimidates catalyzed by the palladium(II) complex [[COP-OAc].sub.2] is used for the asymmetric synthesis of chiral branched allylic esters and the nature of the catalytic mechanism and its rate- and enantiodetermining steps are analyzed. The results are consistent with a novel mechanism in which chelation of the imidate nitrogen to form a cationic palladium(II) intermediate has activated the alkene by external carboxylate in the enantiodetermining step.

A convenient synthesis of [beta]-hydroxynitriles from enantiomerically enriched 3-unsubstituted 2-isoxazolines is described by using a base-catalyzed ring-opening reaction taking place without loss of enantiopurity. The ring-opening along with organocatalytic enantioselective synthesis of 3-unsubstituted 2-isoxazolines has enabled a short 2-step synthesis of [beta]-hydroxynitriles from [alpha],[beta]-unsaturated aldehydes in high enantiomeric purity.

NMR techniques including saturation transfer difference (STD) NMR and Hadamard-encoded nuclear Overhauser effect measurements are applied to develop a convenient approach for the high-throughput screening of dendrimer-binding drugs. The screening results for insoluble drugs showed that phenylbutazone and sulfamethoxazole prefer to localize in the interior pockets of dendrimer, while mycophenolic acid mostly binds on the dendrimer surface and noncharged insoluble drugs like trimethoprim and primidone does not interact with dendrimers.

The thermally promoted cycloaddition between alkynyliodides and nitrile oxides is described. The process has given excellent regioselectivity with respect to both the iodoalkynes and chloro-oximes and functionalization of the iodoisoxazole motifs is achieved via Suzuki cross-coupling.

4-Bis(methylthio)methylene-2-phenyloxazol-5-one is a versatile template for preparing various 2-phenyl-3,4-substituted oxazoles via nucleophilic ring-opening of oxazolone with various oxygen, nitrogen and carbon nucleophiles and subsequent 5-endo cyclization of the resulting acyclic adducts in the presence of silver carbonate.

The total synthesis of the cytotoxic marine macrolide enigmazole A is described. The sensitive, densely functionalized 2,4-disubstituted oxazole fragment is constructed by using an efficient Negishi-type coupling of an oxazol-2-ylzinc reagent formed directly from the parent ethyl 2-iodooxazole-4-carboxylate by zinc insertion.

The article presents a new direct asymmetric aldol reaction, which uses the chiral bicyclic guanidines as catalysts for the conversion of the 5H-oxazol-4-one complexes. The reaction is shown to be extremely enantioselective and smooth.

The synthesis of 2-oxazolidinones, 2-oxazinones, and cyclic ureas was carried out by using carbon dioxide as a convenient carbonylating agent. The developed method could also be applied for the synthesis of cyclic ureas up to 7-membered rings from the corresponding diamines.

The scope and limitations and the mechanistic aspects of the newly discovered reaction of tetranitromethane (TNM) with electrophilic alkenes in the presence of triethylamine to yield substituted 3-nitroisoxazoles is discussed. The heterocyclization reaction involved a variety of [alpha],[beta]-unsaturated aldehydes, ketones, esters, amides, phosphonates, and nitro and sulfur compounds and gave a wide range of functionalized 3-nitroisoxazoles.

Several experiments are used for examining the acidities of hydrogenation mixtures formed by using the iridium-oxazoline complexes. Simple tests with pH indicators have provided visual evidence that phosphine-based catalyst precursors give more acidic reaction mixtures than the corresponding N-heterocyclic carbene ones and also carbene-for-phosphine ligand substitutions might affect the outcome of catalytic reactions by modifying the acidities of the metal hydrides formed.

N-Sulfonyl oxaziridines have reacted with a broad range of olefins in the presence of iron salts to produce 1,3-oxazolidines. Regioisomeric form of 1,2-aminoalcohols is obtained from the reaction of oxaziridines with olefins, and the sense of regioselectivity is controlled by the appropriate choice of inexpensive, nontoxic, first-row transition-metal catalyst.

An efficient and regioselective protocol is developed for preparing 5-hydroxy-2-isoxazolines, which is versatile synthons for isoxazles, [beta]-hydroxy oximes and [gamma]-amino alcohols. [beta]-Lactams embedded in the skeletons of bioactive natural products are prepared in two steps from [beta]-hydroxy oximes, which has provided a new strategy for the synthesis of this kind of compounds.

Unsaturated acyl phosphonates are shown as excellent hydrogen-bond acceptors in enantioselective organocatalysis. The experimental results are used for discussing the mechanisms for the different reactions, including the approach of the oxazolones, indoles, and 1,3-dicarbonyl compounds to the acyl phosphonate coordinated to the catalyst and the role of the catalyst for the reaction course of the nucleophiles.

The Os[O.sub4]-mediated dihydroxylation of meso-tetraphenylporphyrin N-oxide to obtain two regioisomeric chlorin N-oxides is reported. The crystal structure of a free base porpholactone N-oxide carrying the N-oxide on the oxazolone moiety is also reported.

N-Acetylglucosamine [beta]-O-linked to serine and threonine residues of nucleocytoplasmic proteins (O-GlcNAc) is linked to neurodegeneration, cellular stress response, and transcriptional regulation. The reaction coordinate is defined by using chemical approaches and both Michaelis complex and the oxazoline intermediate are observed.

A direct ruthenium-catalyzed radical chloroalkylation method was developed for N-acyl oxazolidinones capitalizing on valence tautomerism of titanium enolates. The chloroalkylation method provided a pathway for the enantioselective total synthesis of trichloroleucine-derived marine natural product neodysidenin.

Dirhodium tetraaacetate catalyzed reaction of [alpha]-diazo-[beta]-keto-carboxylates and phoshonates with arenecarboxamides has produced 2-aryloxazole-4-carboxylates and 4-phosphonates by carbene N-H insertion and cyclodehydration. The analogous reactions of thiocarboxamides have given the corresponding thiazole-5-carboxylates, -phosphonates and -sulfones.