Psoriasis is an inflammatory skin disease. Microneedle (MN) patches can improve psoriasis treatment outcomes by increasing local drug content in the skin. As frequently relapses, developing intelligent MN-based delivery systems with prolonged therapeutic levels and improved efficiency of great significance. Here, we designed detachable H2O2-responsive gel-based MN containing methotrexate (MTX) epigallocatechin gallate (EGCG) using EGCG as both cross-linkers for needle-composited materials...

Silicon marries a chiral counterion Acid is among the oldest and most versatile of chemical catalysts, but its symmetrical protons can't guide reactions to favor product over mirror image. Chemists have resolved this shortcoming through use conjugate bases. While proton activates substrate, nearby asymmetrically biases space around it. Gatzenmeier et al. extend approach Lewis acid catalysis by silyl cations, which can activate variety substrates in complementary fashion (see Perspective...

Abstract Herein, we describe the first catalytic asymmetric intramolecular [4+2] cycloaddition of in situ generated ortho‐quinone methides. In presence a confined chiral imidodiphosphoric acid catalyst, various salicylaldehydes react with dienyl alcohols to give transient ortho ‐quinone methide intermediates, which undergo an provide highly functionalized furanochromanes and pyranochromanes excellent diastereoselectivity enantioselectivity.

Despite its significant potential, a general catalytic asymmetric [4+2]-cycloaddition of simple and electronically unbiased dienes with any type aldehyde has long been unknown. Previously developed methodologies invariably require activated, engineered substrates. We now provide solution to this problem. show that highly acidic confined imidodiphosphorimidates (IDPis) are extremely effective Brønsted acid catalysts the hetero-Diels–Alder reaction wide variety aldehydes give enantiomerically...

Operationally simple and generally applicable arene nitration with cheap easily accessible chemicals has been a long-sought transformation in the synthetic organic community. In this work, we realized goal nontoxic inexpensive Fe(NO3)3·9H2O as nitro source recyclable solvent hexafluoroisopropanol promotor via network of hydrogen-bonding interactions. As result relative mildness high reliability protocol, late-stage various highly functionalized natural products commercially available drugs...

We describe the design and development of first catalytic asymmetric vinylogous Prins cyclization. This reaction constitutes an efficient approach for highly diastereo- enantioselective synthesis tetrahydrofurans (THFs) is catalyzed by a confined chiral imidodiphosphoric acid (IDP). Aromatic heteroaromatic aldehydes react with various 3,5-dien-1-ols to afford 2,3-disubstituted THFs in excellent selectivity (d.r. > 20:1, e.r. up 99:1). Aliphatic similarly results when acidic...

Despite tremendous advances in enantioselective catalysis of the Diels–Alder reaction, use simple α,β-unsaturated esters, one most abundant and useful class dienophiles, is still severely limited scope due to their low reactivity. We report here a catalytic asymmetric methodology for large variety methyl esters different dienes based on extremely reactive silylium imidodiphosphorimidate (IDPi) Lewis acids. Mechanistic insights from accurate domain-based local pair natural orbital...

Abstract In canonical organic chemistry textbooks, the widely adopted mechanism for classic transetherifications between ethers and alcohols starts with activation of ether in order to weaken C–O bond, followed by nucleophilic attack alcohol hydroxy group, resulting a net C–O/O–H σ-bond metathesis. this manuscript, our experimental computational investigation Re 2 O 7 mediated ring-closing transetherification challenges fundamental tenets traditional mechanism. Instead activation,...

<title>Abstract</title> Nature has a delicate system for catalysis due to optimization through evolution, which often displays unparalleled efficiency and selectivity. “learning from nature” is popular effective approach in designing new reactions catalysts when traditional strategies fail. Here, we proved that it can be highly rewarding consider nature’s repertoire of during the effort facilitate challenging heterolytic C–O bond cleavage methanol (MeOH) by studying its metabolism...

In this manuscript, inspired by the natural S‐adenosylmethionine (SAM) cycle, we devised a mixed σ‐bond metathesis between (sp3)C–S bond of organic sulfides with C–O alcohols. This reaction is mediated readily available and operationally facile mixture AlCl3 ZnI2, which allows fast access to various challenging directly editing easily ones. Like multiple metathesis, method could also be rendered intramolecular extended ether (sp3)C–O as well amine (sp3)C–N provide saturated heterocycles such...

We describe in this work an operationally facile and generally applicable ipso-nitration of boronic esters by Fe(NO3)3·9H2O hexafluoroisopropanol (HFIP), allowing us fast access to various nitroarenes that are currently difficult obtain via traditional electrophilic C–H nitrations. In contrast previous deborylative ipso-nitrations, new protocol utilized less reactive more stable organoboron reagents therefore had significantly improved substrate scope functional group tolerance, which was...

Complexity from simplicity: Polycyclic ethers are synthesized by cascade reactions involving the use of epoxides as electrophilic traps in transposition allylic alcohols. Stereogenic centers created functionalizing prochiral sites under thermodynamic control, and remote stereoinduction can be achieved through ketones conduits. As a service to our authors readers, this journal provides supporting information supplied authors. Such materials peer reviewed may re-organized for online delivery,...

This manuscript describes the application of Re₂O₇ to syntheses diarylmethanes from benzylic alcohols through solvolysis followed by Friedel–Crafts alkylation.

We report synthetic methods to produce silver (Ag) or gold (Au) monodisperse nanoparticles with different loadings as well Ag and Au nanorods tunable aspect ratios optical properties. This is achieved inside externally functionalized mesoporous SBA-15 material by utilizing a simple change of the type metal complex that reduced imines hemiaminals were anchored within channel walls material. The imine hemiaminal groups produced reacting grafted 3-aminopropyl CH3CHO HCHO, respectively. Upon...

The abilities of Re2O7 to promote non-stereoselective allylic alcohol transposition reactions and acetal ionization or enone activation have been coupled for a heterocycle synthesis in which thermodynamics dictate stereochemical outcomes. stabilities intermediate cation oxocarbenium ion intermediates the efficiency product equilibration. Long range stereoinduction can be observed spiroketals spirotricycles through this protocol.

Allylic alcohols undergo transposition reactions in the presence of Re2 O7 whereby equilibrium can be dictated by trapping one isomer with a pendent electrophile. Additional ionization occur when group is an aldehyde or ketone, thus leading to cyclic oxocarbenium ion formation. Terminating process through bimolecular nucleophilic addition into intermediate provides versatile method for synthesis diverse oxygen-containing heterocycles. Understanding relative rates steps sequence leads design...

Die erste katalytisch-asymmetrische intramolekulare [4+2]-Cycloaddition von in situ generierten ortho-Chinonmethiden wurde entwickelt. Katalysiert durch eine abgeschirmte chirale Imidodiphosphorsäure, reagieren diverse Salicylaldehyde mit Dienylalkoholen zu kurzlebigen ortho-Chinonmethid-Intermediaten, die hoch funktionalisierten Furan- und Pyranchromanen exzellenten Diastereo- Enantioselektivitäten umgewandelt werden.

We report on adsorption and release of the anticancer drugs cisplatin transplatin from mesoporous silica nanomaterials, emphasizing differences between its much less toxic isomer. Two types particles, MCM-41 SBA-15, were used, either as just synthesized or after calcination to remove templates. The particles characterized by TEM, nitrogen physisorption, elemental analysis. UV−vis spectra obtained intensities several bands (205−210 nm, 210−220 220−235 300−330 nm) found proportional drug...

A general and highly efficient intramolecular dehydrative Friedel–Crafts reactions via Re 2 O 7 mediated hydroxyl group activation is described for the syntheses of tetrahydronaphthalene, tetrahydroquinoline, tetrahydroisoquinoline, chromane, isochromane derivatives.

In this paper, we describe a Re2O7-mediated ring-opening arylation of unactivated arylcyclopropane because its functionalization with various arenes via Friedel–Crafts-type reactivity. This protocol allows facile access to functionalized 1,1-diaryl alkanes and is characterized by broad substrate scope, mild reaction conditions, high efficiency, atom economy. Both density functional theory calculations deuterium labeling experiments were carried out justify the indispensable role HFIP in...

Abstract Recyclable and efficient heterogeneous catalysts have been prepared by embedding dirhodium(II,II) core carboxylate complexes into the amine‐functionalized nanosized channels of a mesoporous silica host, amine–SBA‐15. Two alternative synthetic procedures for preparation developed adapted immobilization dirhodium variable Lewis acidity. The catalytic activity resulting solid materials has evaluated in model cyclopropanation reactions styrene at reaction conditions (reaction substrate,...

Here, we describe an activation mode for unactivated alkenes on the basis of a synergy between Re2O7/HReO4 and hexafluoroisopropanol (HFIP). Highly electron-deficient styrenes have been activated to effect challenging intermolecular hydroarylation with different arenes give variety diarylalkanes in high efficiency. This method is characterized by mild reaction condition, broad substrate scope, chemical yields, minimal waste generation. The potential synthetic application this methodology was...