Hitting the right target: Differentiation between two keto moieties was accomplished by a regio- and enantioselective bioamination employing ω-transaminases. Using 1,5-diketones as substrates gave access to the optically pure 2,6-disubstituted piperidine scaffold. The approach allowed the shortest synthesis of the alkaloid dihydropinidine, as well as its enantiomer, through the choice ...

An unusual dinuclear chiral iron complex has been synthesized and effectively utilized in the asymmetric hydrophosphorylation of aldehydes to synthesize optically active α-hydroxy phosphonates with excellent yield and good enantioselectivity.

Just a spoonful of sugar! A new synthetic strategy involving the use of deoxygenative olefination reaction as the key step was developed for the preparation of deoxy and iminosugars in their optically active form. This strategy has been proven successful by the use of a pentose, hexose, heptose, and disaccharide ...

Catalytic asymmetric sulfenylation of unprotected 3-substituted oxindoles has been developed via cooperative catalysis of a chiral N,N'-dioxide-Sc(OTf)(3) complex and a Brønsted base. Utilizing readily available N-(phenylthio)phthalimide as the sulfur source, a wide range of optically active 3-phenylthiooxindoles were obtained in excellent yields with excellent enantioselectivities under mild reaction conditions.

Treatment of an optically pure tartaric acid-derived diiodide and various secondary phosphine oxides with LHMDS provides the corresponding aryl group-modified DIOP dioxides (Ar-DIOPOs). The activities of Ar-DIOPOs as Lewis base catalysts were investigated for several asymmetric transformations using chlorosilane reagents. The p-tolyl-substituted DIOPO (p-tolyl-DIOPO) was most effective for the reductive ...

With certain amounts of sodium tert-butoxide and tert-butanol as additives, catalytic amounts of an inexpensive and easy-to-handle copper source Cu(OAc)(2) ⋅H(2) O, a commercially available and air-stable non-racemic dipyridylphosphine ligand, as well as the stoichiometric desirable hydride donor polymethylhydrosiloxane (PMHS), formed a versatile in situ catalyst system for the enantioselective ...

An optically active tetrahydroquinoline intermediate () was prepared in 8 steps from monoprotected ethylene glycol, using a Pd-catalysed aza-Michael reaction to induce chirality. This can be transformed into three Galipea alkaloids (angustureine, galipeine and cuspareine). The proximity of a benzyloxy group is found to exert profound effects in several steps ...

A highly enantioselective Biginelli reaction promoted by chiral spirocyclic SPINOL-phosphoric acids has been developed. Under the optimized conditions with 5 mol% catalyst loading, a wide range of optically active dihydropyrimidinethiones (DHPMs) were obtained in high yields (up to 98%) with good to excellent enantioselectivities (up to 99% ee). The synthetic ...

A catalytic asymmetric N-nitroso aldol reaction of γ,δ-didehydro-δ-lactones with nitrosoarenes was achieved using chiral tin dibromide as the chiral precatalyst and sodium ethoxide as the base precatalyst in the presence of ethanol. Optically active α-hydroxyamino ketones with up to 99% ee were regioselectively obtained in moderate to high yields from ...

β-Isocupreidine () catalyzed asymmetric [4 + 2] cycloaddition of β,γ-unsaturated α-ketoesters with allenic esters afforded ester-substituted functionalized dihydropyran derivatives in high yields along with high enantioselectivities under mild conditions.

Optically active ent-calystegine B4 was prepared in 13 steps from commercially available chiral l-dimethyl tartrate. The synthesis was achieved by the Michael addition and the aldol reaction of nitromethane to form cycloheptanone in a stereoselective manner. Reduction of the nitro group in the presence of Boc(2)O accomplished an efficient conversion ...

An organocatalytic construction of optically enriched substituted pyran derivatives via amine-catalyzed Michael addition and subsequent enolization/cyclisation has been described starting from electronically poor alkenes. Functionalized pyrans were obtained in high enantioselectivities (up to 96%) and good yields (up to 90%) having three contiguous chiral centers.

[6]-Azaosmahelicenes, the first d(4)-heterometallahelicenes, have been synthesised and fully characterised. Their optical properties (UV-Vis absorption and luminescence) are reported.

A stereoselective [3+2] cycloaddition of isocyanoesters to methyleneindolinones catalyzed by a quinine-based thiourea-tertiary amine has been successfully developed. Just by tuning the protecting groups on substrates, a variety of optically enriched 3,3'-pyrrolidinyl spirooxindole diastereomers could be obtained in excellent enantioselectivities (up to 99% ee).

Amide nucleophiles on demand: Rationally designed pyrazoleamides function as Michael donors in urea-catalyzed asymmetric Michael reactions with excellent chemical and optical yields. The pyrazoleamide group performs as an ester equivalent, a directing group, an activating group, and functions as a good leaving group in further transformations of the product.

A series of multifunctional catalysts with two chiral diaminocyclohexane units were developed and successfully applied in the asymmetric oxa-Michael-aza-Henry cascade reaction of salicylaldimines with nitroolefins. This approach provides a simple and efficient entry to polysubstituted chiral 4-aminobenzopyrans with three consecutive stereocenters and in high yield (up to 97%) with excellent ...

Highly useful optically active 1-(1-alkynyl)cyclopropyl ketones can be efficiently obtained by the kinetic resolution of the easily available racemic ones under the catalysis of the chiral gold(i) species. Reaction scope and synthetic applications are also investigated.

An efficient synthetic route to optically pure norcantharidin analogue NCA-01, a highly selective inhibitor of protein phosphatase 2B (PP2B; calcineurin), has been developed. The absolute stereochemistry of the enantiomers was determined by X-ray crystallographic analysis. Optically pure NCA derivatives that had various substituents at the C1 position were synthesized in ...

Non-naturally enantioenriched cis-β-thio-α-amino acid derivatives were synthesized through one pot, cascade thio-Michael/ring opening reaction of aromatic thiols with (Z)-olefinic azlactones in good yields with high levels of diastereoselectivities and enantioselectivities, which was catalyzed by a chiral bifunctional thiourea-tertiary amine catalyst.

Optically active 1,3-bridged cyclobutanes 10 of the bicyclo[3.1.1]heptane ring system and 1,2-bridged cyclobutanes 11 of the bicyclo[3.2.0]heptane ring system were produced by UV irradiation of alpha,beta,gamma,delta-unsaturated esters 9a and 9c-f. The preference of endo-stereochemistry at C-6 bridged head was observed in cross-adducts 10. On the other hand, irradiation of conjugated ...

2-Benzazepines, which are potentially good candidates for new drug therapies to treat skin wounds, were readily prepared from substituted cinnamylamide via an intramolecular Friedel-Crafts reaction. With few steps and effective reactions, the procedure enables a rapid derivatization of 2-benzazepines. Moreover, optically active 4-substituted-2-benzazepines were prepared from chiral α-substituted cinnamylamides, which ...

Enantioselective mono-fluorination of α-keto esters was achieved using a mildly basic palladium μ-hydroxo complex as catalyst. Subsequent one-pot reduction afforded optically active β-fluoro-α-hydroxy esters. These compounds were then converted into β-fluoro-α-amino esters, which are potentially useful in medicinal chemistry research.

(±)-3,4-Methylenedioxymethamphetamine (MDMA, also known as "ecstasy") is a psychoactive drug with selective neurotoxic potential toward brain serotonin (5-HT) neurons. One hypothesis holds that MDMA neurotoxicity may at least partially be a consequence of its metabolism. In most species (including primates), O-demethylenated MDMA metabolites such as N-methyl-α-methyldopamine (HHMA) have been postulated ...

A six-step synthesis of (+/-)-7-hydroxylycopodine that proceeds in 5% overall yield has been achieved. The key step is a Prins reaction in 60% sulfuric acid that gave the key tricyclic intermediate with complete control of the ring fusion stereochemistry. A one-pot procedure orthogonally protected the primary alcohol as an acetate ...

The catalytic asymmetric aziridination of imines and diazo compounds (AZ reaction) mediated by boroxinate catalysts derived from the VANOL and VAPOL ligands was investigated with chiral imines derived from five different chiral, disubstituted, methyl amines. The strongest matched and mismatched reactions with the two enantiomers of the catalyst were noted ...

Asymmetric nucleophilic monofluoroalkylation of a broad range of aldehydes with an α-fluoro-γ-sulfinylbenzyl carbanion takes place with complete control of the facial selectivity at the carbanion and good to high anti-diastereoselectivity to give easily separable mixtures of two optically pure 1,2-fluorohydrin derivatives (up to 24:1 anti/syn). Separation and removal of the ...

A series of twenty optically pure 3,4-dihydro-5H-pyrido[1',2':1,2]imidazo[4,5-d][1,3]diazepin-5-ones which form a new family of azaheterocycle-fused [1,3]-diazepines were synthesized in four steps with 17-66% overall yields. The key step consists in a selective C-acylation reaction of easily accessible 2-amino-imidazo[1,2-a]pyridine at C-3.

Poly(butylene succinate) (PBS)/graphene oxide (GO) nanocomposites were facilely prepared via in situ polymerization. The properties of the nanocomposites were studied using FTIR, XRD, 1HNMR, and the state of dispersion of GO in the PBS matrix was examined by SEM. The crystallization and melting behavior of the PBS matrix in the ...

A new synthetic route to optically active unsaturated γ- and δ-lactones has been demonstrated via asymmetric allylic carboxylation with a planar-chiral Cp'Ru catalyst and ring-closing metathesis reaction with a Grubbs II catalyst, and successfully applied to the enantioselective synthesis of (R)-(-)-massoialactone.

Macroscopic graphene fibers with strength comparable to carbon nanotube yarns have been fabricated with a facile dimensionally-confined hydrothermal strategy from low-cost, aqueous graphite oxide suspensions, which is shapable, weavable, and has a density of less than 1/7 conventional carbon fibers. In combination with the easy in situ and post-synthesis functionalization, ...

Intramolecular conjugate displacement (ICD), the process illustrated in Scheme 1, has been applied to the Morita-Baylis-Hillman adducts formed from (5S)-5-(l-menthyloxy)-2(5H)-furanone and aldehydes that carry a protected beta- or gamma-amino group. DIBAL-H reduction of the resulting ICD products releases optically pure six- or seven-membered cyclic amines having a stereogenic center alpha ...

A zinc-mediated addition of methyl and terminal alkynes to chiral N-tert-butanesulfinyl ketimines for the preparation of optical quaternary 3-amino oxindoles was reported. In general, the operationally simple reaction affords the desired products in high yields and good to excellent diastereoselectivities. Subsequent convenient cleavage of sulfinyl protecting group under mild conditions ...

An enantioselective synthesis of γ-nitroesters by a one-pot asymmetric Michael addition/oxidative esterification of α,β-unsaturated aldehydes is presented. The procedure is based on merging the enantioselective organocatalytic nitroalkane addition with an N-bromosuccinimide-based oxidation. The γ-nitroesters are obtained in good yields and enantioselectivities, and the method provides an attractive entry to optically ...

To facilitate precatalyst recovery and reuse, we have developed a fluorous, oxime-based palladacycle 1 and demonstrated that it is a very efficient and versatile precatalyst for a wide range of carbon-carbon bond formation reactions (Suzuki-Miyaura, Sonogashira, Stille, Heck, Glaser-type, and Kumada) in either aqueous or organic medium under microwave irradiation. ...

Allylic gem-dichlorides undergo regio- and enanantioselective (er up to 99:1) copper-catalyzed allylic alkylation with Grignard reagents affording chiral Z-vinyl chlorides. This highly versatile class of synthons can be subjected to Suzuki cross coupling affording optically active Z-alkenes and 1,3-cis,trans dienes.

A straightforward functionalization of d-pentoses is reported, which affords homoallylaminopolyols in two steps and uses ion exchange chromatography as the only purification operation. The key indium-mediated allylation is effected on unprotected glycosylamines and occurs with good to excellent syn stereoselection. Validation of the synthetic utility of the method was exemplified ...

An efficient and practical synthesis of optically pure β-pyrazole-substituted alcohols was achieved from an asymmetric ring-opening reaction of meso-epoxides with pyrazole derivatives as the nucleophile. In the presence of 1 mol % of N,N'-dioxide-Sc(OTf)(3) complex, excellent enantioselectivity and yields were obtained from meso-epoxides. The process could also be used for the mixture ...

CuBr and ZnI(2) have been developed as catalysts or subcatalysts for the efficient asymmetric synthesis of axially chiral allenols with up to 97% ee from readily available propargylic alcohols, aliphatic or aromatic aldehyde, pyrrolidine, and commerically available ligands. The alcohol unit in the terminal alkynes plays a very important role ...

Chiral SPINOL-phosphoric acids are highly enantioselective catalysts for the asymmetric Pictet-Spengler reaction of N(b) -α-naphthylmethyl tryptamines with a series of aliphatic and aromatic aldehydes, affording optically active tetrahydro-β-carbolines in excellent yields and ee values. The current protocol has been applied in the asymmetric total synthesis of (-)-harmicine.

A simple high-yield three-steps route to optically active 4-hydroxymethyl-3-(1H-indolyl)oxazolidin-2-ones from (S)-glycidol is described. The key intermediates (R)-oxiran-2-ylmethyl 1H-indol-4/-5-ylcarbamates are obtained in high yields from (S)-glycidol. These are readily transformed to oxazolidin-2-ones, very interesting building blocks in drug synthesis. Chirality, 2012. © 2012 Wiley Periodicals, Inc.

A series of functionalized diaza- and tetraazatetracenes was synthesized, either by condensation of an aromatic diamine with an ortho-quinone/diethyloxalate followed by chlorination with POCl(3) to give diazatetracenes or by palladium-catalyzed coupling of a phenylenediamine with various 2,3-dichloroquinoxalines to give tetraazatetracenes (after oxidation with MnO(2) ). Representative examples included halogenated and ...

The preparation of optically pure quaternary piperidines, both fluorinated and non-fluorinated, has been achieved from a chiral imino lactone derived from (R)-phenylglycinol. In the case of the fluorinated derivatives, the addition of (trifluoromethyl)trimethylsilane (TMSCF(3) ) followed by iodoamination and migration of the CF(3) group allowed access to four derivatives of ...

Asymmetric aldol reactions catalyzed by a novel polystyrene-immobilized proline derivative occur in short reaction times with excellent diastereo- and enantioselectivity. The catalyst can be recovered by simple filtration and shows very high reusability. The high activity depicted by the supported catalyst and its chemical and mechanical stability have allowed its ...

ZnO tetrapods (ZnO-Ts) were synthesized in a vertical flow reactor by gas phase oxidation of Zn vapor in an air atmosphere. The morphology of the product was varied from nearly spherical nanoparticles to ZnO-Ts, together with the partial pressure of Zn and reaction temperature. MgO introduced during synthesis, increased the ...

Merging three in one by a three-component organocatalytic asymmetric reaction of imines, α-bromoesters, or ketone with α,β-unsaturated aldehydes provides optically active pyrrolo-isoquinolines-an important class of molecules in life science. The reaction proceeds with excellent enantioselectivity and a number of transformations of the products obtained demonstrated the potential of the new ...

This Communication reports optically active helical substituted polyacetylenes which solely catalyzed asymmetric Aldol reaction between cyclohexanone and p-nitrobenzaldehyde; more importantly the helical structures are found to play crucial roles in the asymmetric catalysis, with a remarkable yield and ee (both up to 80%). A synergic effect is observed between the ...

Porophyllum tagetoides is an annual warm-weather herb that has an intense typical smell. Its leaves are commonly used in soup preparation and traditional medicine for treatment of inflammatory diseases. Its volatile compounds and antioxidant properties were evaluated in crude, aqueous and ethanol leaf extract and an oil emulsion using different ...

The total synthesis of the putative structure of stagonolide D has been completed. The relative and absolute configuration of stagonolide D was established by synthesizing its optical antipode. The adopted strategy involves the construction of the central macrolide employing ring-closing metathesis (RCM) followed by selective protecting group manipulations and a ...

Highly selective: The title reaction is achieved with high enantiomeric and geometric control and thermodynamically unstable (Z)-enone derivatives are obtained as the major products. The procedure tolerates a wide range of substrates to generate optically active pyrazolones with vinyl-substituted quaternary stereocenters.

Chiral oxazolines: A synthetic method to prepare optically active oxazolines through a copper-catalyzed asymmetric desymmetrization of 1,3-diols has been successfully developed. This reaction system tolerated a diverse range of substrates to give the desired oxazoline derivatives in good to excellent yields with high enantioselectivities.