A new cytotoxic and antiviral cyclic tetrapeptide, asperterrestide (1), a alkaloid, terremide C (2), aromatic butenolide, aspernolide E (3), together with 10 known compounds were isolated from the fermentation broth of marine-derived fungus Aspergillus terreus SCSGAF0162. Their structures elucidated by spectroscopic analysis, absolute configuration 1 was determined Mosher ester technique analysis acid hydrolysates using chiral-phase HPLC column. Compound contains rare 3-OH-N-CH3-Phe residue...

Ring-opening polymerization of O-carboxyanhydrides (OCAs) can furnish polyesters with a diversity functional groups that are traditionally hard to harvest by lactones. Typical ring-opening catalysts subject unavoidable racemization most OCA monomers, which hampers the synthesis highly isotactic crystalline polymers. Here, we describe an effective bifunctional single-molecule organocatalysis for selective OCAs without epimerization. The close vicinity both activating in same molecule...

Abstract Catalytic asymmetric synthesis of helically chiral molecules has remained an outstanding challenge and witnessed fairly limited progress in the past decades. Current methods to construct such compounds almost entirely rely on catalytic enantiocontrolled fused-ring system extension. Herein, we report a direct terminal peri -functionalization strategy, which allows for efficient assembling 1,12-disubstituted [4]carbohelicenes via organocatalyzed enantioselective amination reaction...

Lewis acid-catalyzed cycloaddition between bicyclo[1.1.0]butanes (BCBs) and unsaturated substrates has recently been demonstrated to be a powerful strategy for synthesizing bicyclo[2.1.1]hexanes. However, their reaction mechanisms remain elusive. This computational work explored the developed TMSOTf-catalyzed of BCB ketone ketene determined rate-determining step as activation ketone. Contrary previous proposal enolate active species, this instead identified catalytically species partially...

Eight new chromones, engyodontiumones A–H (1–8), and three phenol derivatives (9–11) together with eight known polyketides (12–19) were isolated from the deep-sea-derived fungus Engyodontium album DFFSCS021. Their structures identified by extensive spectroscopic analysis. Compounds 8 16 showed significant selective cytotoxicity against human histiocytic lymphoma U937 cell line IC50 values of 4.9 8.8 μM, respectively. In addition, this is first time to report that 8, 15 had mild antibacterial...

Homogeneous catalysis and biocatalysis have been widely applied in synthetic, medicinal, energy chemistry as well synthetic biology. Driven by developments of new computational methods better computer hardware, has become an essentially indispensable mechanistic "instrument" to help understand structures decipher reaction mechanisms catalysis. In addition, synergy between experimental deepens our understanding, which further promotes the rational design catalysts. this Account, we summarize...

The design and synthesis of metal–organic frameworks (MOFs) for direct use as electrode materials are crucial enhancing the electrocatalytic oxygen evolution reaction (OER). Herein, ultrathin MIL-53(Fe) nanosheet arrays with enriched coordinatively unsaturated metal sites (denoted MIL-53(Fe)/NF-B0.2-2) obtained under inhibition modulation benzoic acid (BA) ligands via a substitution-suppression process. results confirm that this unique structure effectively increases electrochemical active...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAsymmetric hydrogenation of cycloalkanones catalyzed by BINAP-iridium(I)-aminophosphine systemsXiaoyong Zhang, Takanao Taketomi, Takashi Yoshizumi, Hidenori Kumobayashi, Susumu Akutagawa, Kazushi Mashima, and Hidemasa TakayaCite this: J. Am. Chem. Soc. 1993, 115, 8, 3318–3319Publication Date (Print):April 1, 1993Publication History Published online1 May 2002Published inissue 1 April...

A readily available ruthenium(II) catalyst was developed for the catalytic hydrogenation of aldehydes with a TON (turnover number) up to 340000. It can be performed without base and solvent, showing highly industrial potential. High chemoselectivity achieved in presence alkenyl ketone groups. Further application this protocol glucose reduction showed good efficiency. Theoretical studies revealed that rate-determining step is step, not carboxylate-assisted H2 activation step.

Abstract Anion‐binding can regulate anion transport in chloride channels through dynamic non‐covalent interactions, which gives insights into the designing of new organocatalytic transformations but is surprisingly unexplored polymerization catalysis. Herein, we describe an effective unimolecular anion‐binding organocatalysis where 4‐(dimethylamino)pyridine anchored to a thiourea for ring‐opening O ‐carboxyanhydrides (OCAs) furnish highly isotactic poly(phenyllactic acid) (Ph‐PLA) with...

Abstract Hetero-Diels-Alder (HDA) reaction is an important synthetic method for many natural products. An iron(III) catalyst was developed to catalyze the challenging HDA of unactivated aldehydes and dienes with high selectivity. Here we report extensive density-functional theory (DFT) calculations molecular dynamics simulations that show effects iron (including its coordinate mode and/or spin state) on this reaction: considerably enhancing dynamically stepwise process, broadening entrance...

A highly selective ruthenium-catalyzed C–H activation/annulation through a pathway involving N–O bond cleavage prior to alkyne insertion is developed.

A palladium-catalyzed reaction of N-propargyl oxazolidines with alkenes for the synthesis indolizidines has been developed. Through a sequential 6-exo-dig cyclization/proton transfer/[3+2] cycloaddition/cycloreversion/aromatization process, series fused polycyclic indolizines are obtained in moderate to good yields high functional group tolerance. Experimental and theoretical studies suggest that [3+2] cycloaddition/cycloreversion oxazolidine ring probably involves C-C C-O bond cleavage,...

Three pairs of new axially dissymmetric bisphosphane ligands, (R)-(–)- and (S)-(+)-2,2′-bis(dicyclohexylphosphanyl)-1,1′-binaphthyl [(R)-(–)-and (S)-(+)-Cy-BINAP, (R)-(–)-and (S)-(+)2], (R)-(+)- (S)-(–)-2,2′-bis(diphenylphosphanyl)-5,5′,6, 6′,7,7′,8,8′-octahydro-1,1′-binaphthyl [(R)-(+)- (S)-(–)-H8-BINAP, (S)-(–)-3], (S)-(+)2,2′-bis(dicyclohexylphosphanyl)-5,5′,6,6′,7,7′, 8,8′-octahydro-1,1′-binaphthyl [(R)-(–)- (S)(+)-Cy-H8-BINAP, (S)-(+)-4], have been synthesized. The absolute...

Asymmetric hydrogenation of a series α,β-unsaturated carboxylic acids catalyzed by the H8-BINAP-Ru(II) complexes, Ru(OCOCH3)2[(S)-H8-binap] and [RuI((R)-H8-binap)(p-cymene)]I [H8-BINAP = 2,2′-bis(diphenylphosphino)-5,5′,6,6′,7,7′,8,8′- octahydro-1,1′-binaphthyl], affords corresponding saturated in excellent enantioselectivities (86-97%). This reaction has also been applied to synthesis (S)-ibuprofen 97% ee.

In this work, the preparation, characterization and removal capabilities of a novel biomass derived BC its BCN nanocomposites are described. Possessing hierarchically porous structures, extremely large surface areas special chemical bonds, nanosheets have demonstrated advantages in terms their adsorption photocatalytic activities. The activities as-prepared catalysts were evaluated by degradation RhB. best results exhibited 97% 95% decomposition RhB which obtained using BCN-40 within 120 min...

Recently, a lactate racemase was discovered as new Ni-dependent enzyme with unique tethered NAD-like cofactor. We report the first computational study aimed at deciphering previously unclear role of Ni-tethered cofactor in reactions racemase. Our calculations revealed that increases dehydrogenation barriers. The formation metastable NADH-like pyruvate intermediate and two nearby histidine bases are proposed key factors racemization reaction. Such destabilization intermediates by is uncommon...

Practical and simple catalytic enantioselective hydrogenation reactions to synthesize N-unprotected β-amino esters have been developed: (1) asymmetric of β-enamine ester (2) direct reductive amination β-keto using ammonium salts. A Ru–DM-SEGPHOS complex was used as the catalyst in both cases gave high enantioselectivity, reactivity, wide substrate applicability. These protocols greatly reduced reaction time waste compared conventional synthetic routes. The route demonstrated on a >100 kg scale.

Enantioselective [2 + 2] cyclization between an imine and a carbon–carbon double bond is versatile strategy to build chiral azetidines. However, α-branched allenoates have never been successfully applied in reactions with imines, as they always undergo Kwon's [4 annulation previous catalytic methods. Herein, simple situ generated magnesium catalyst was employed achieve the enantioselective reaction of DPP-imines for first time. Insightful experiments including KIE experiments, controlled...

Structures and transport behaviors around the ionomer–catalyst interface in polymer electrolyte membrane fuel cells (PEMFCs) have aroused great research interests recent years. Herein, classical molecular dynamics simulation method is used to investigate interfacial self-assembly phenomena of three fully hydrated (λ = 23) Nafion films with thicknesses 2.4, 5.0 7.3 nm on platinum surface. Interestingly, it found that vicinity surface, there an ultra-dense adhesive ionomer layer a thickness...