José Alemán

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Defects and Disorder in Covalent Organic Frameworks for Advanced Applications

Saba Daliran, Matías Blanco, Amarajothi Dhakshinamoorthy, Ali Reza Oveisi, more

Advanced Functional Materials > 34 > 18 > n/a - n/a

Crystalline porous organic polymers (CPPs) or covalent organic frameworks (COFs), are composed by light elements linked by covalent bonds. Despite the remarkable progress attained, there are still bottlenecks limiting further development, some of them related to the presence of defects during their synthesis as well as in‐depth understanding of structure of active centers and/or details of the reaction...

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Enhancing the Photocatalytic Activity via Direct Covalent Functionalization in Single‐Walled Carbon Nanotubes

José Luis Nova‐Fernández, Daniel González‐Muñoz, Gustavo Pascual‐Coca, Mattia Cattelan, more

Advanced Functional Materials > 34 > 14 > n/a - n/a

Herein, the direct covalent functionalization of single‐walled carbon nanotubes (SWNT) is presented with an amino‐decorated phenyl‐phenothiazine (PTH‐NH₂) organophotocatalyst through the diazonium chemistry protocol. Three different SWNT‐PTH hybrids are prepared by varying the amount of PTH‐NH₂ and diazonium agent and are fully characterized. These hybrids differ not only in the degree of functionalization,...

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Rapid and Safe Continuous‐Flow Simmons‐Smith Cyclopropanation using a Zn/Cu Couple Column

José Luis Nova‐Fernández, Gustavo Pascual‐Coca, Silvia Cabrera, José Alemán

Advanced Synthesis & Catalysis > 366 > 4 > 710 - 716

Flow chemistry has recently opened new chemistry windows thanks to the safer use of hazardous and sensitive reagents. Furthermore, flow procedures usually outperform their batch counterparts due to improved mass and heat transfer, offering a good opportunity for industrial application. Herein, a rapid Simmons‐Smith cyclopropanation flow process is presented. Taking advantage of the in situ production...

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Recent Advances in the Use of Covalent Organic Frameworks as Heterogenous Photocatalysts in Organic Synthesis

Alberto López‐Magano, Saba Daliran, Ali Reza Oveisi, Rubén Mas‐Ballesté, more

Advanced Materials > 35 > 24 > n/a - n/a

Organic photochemistry is intensely developed in the 1980s, in which the nature of excited electronic states and the energy and electron transfer processes are thoroughly studied and finally well‐understood. This knowledge from molecular organic photochemistry can be transferred to the design of covalent organic frameworks (COFs) as active visible‐light photocatalysts. COFs constitute a new class...

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Nickel‐Catalysed Cross‐Electrophile Coupling of Benzyl Bromides and Sulfonium Salts towards the Synthesis of Dihydrostilbenes

Roberto Río‐Rodríguez, Laura Blanco, Alba Collado, Jose A. Fernández‐Salas, more

Chemistry – A European Journal > 28 > 54 > n/a - n/a

A nickel‐catalysed reductive cross‐coupling reaction between benzyl sulfonium salts and benzyl bromides is reported. Simple, stable and readily available sulfonium salts have shown their ability as leaving groups in cross‐electrophile coupling, allowing the formation of challenging sp³–sp³ carbon‐carbon bonds, towards the synthesis of interesting dihydrostilbene derivatives. In addition, benzyl tosyl...

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Remote Giese Radical Addition by Photocatalytic Ring Opening of Activated Cycloalkanols

Noelia Salaverri, Benedetta Carli, Patricia B. Gratal, Leyre Marzo, more

Advanced Synthesis & Catalysis > 364 > 10 > 1689 - 1694

The application of proton coupled electron transfer (PCET) processes in organic synthesis has opened the door to new radical intermediates for synthesis such as alkyl radicals in remote positions to a ketone. Herein, we present the addition of these remote alkyl radicals to electron deficient double bonds under photoorganocatalyzed and very mild conditions. The method is not only applicable to diactivated...

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Fluorinated Sulfinates as Source of Alkyl Radicals in the Photo‐Enantiocontrolled β‐Functionalization of Enals

Ricardo I. Rodríguez, Marina Sicignano, José Alemán

Angewandte Chemie International Edition > 61 > 9 > n/a - n/a

The generation of sulfonyl radicals has long been known as a flexible strategy in a wide range of different sulfonylative transformations. Meanwhile their use in alkylation processes has been somehow limited due to their inherent difficulty in evolving to less‐stable radicals after sulfur dioxide extrusion. Herein we report a convenient strategy that involves gem‐difluorinated sulfinates as an “upgrading‐mask”,...

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Fluorinated Sulfinates as Source of Alkyl Radicals in the Photo‐Enantiocontrolled β‐Functionalization of Enals

Ricardo I. Rodríguez, Marina Sicignano, José Alemán

Angewandte Chemie > 134 > 9 > n/a - n/a

The generation of sulfonyl radicals has long been known as a flexible strategy in a wide range of different sulfonylative transformations. Meanwhile their use in alkylation processes has been somehow limited due to their inherent difficulty in evolving to less‐stable radicals after sulfur dioxide extrusion. Herein we report a convenient strategy that involves gem‐difluorinated sulfinates as an “upgrading‐mask”,...

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Frontispiece: Organocatalytic Strategies for the Development of the Enantioselective Inverse‐electron‐demand Hetero‐Diels‐Alder Reaction

Víctor Laina‐Martín, Jose A. Fernández‐Salas, José Alemán

Chemistry – A European Journal > 27 > 49 > n/a - n/a

Inverse‐electron‐demand hetero‐Diels‐Alder reactions have been an important breakthrough for the synthesis of heterocyclic compounds. Among all their variants, the organocatalytic enantioselective version has been widely explored since the asymmetric construction of diversely functionalized scaffolds under reaction conditions encompassed within the green chemistry field is of great interest. A profound...

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Organocatalytic Strategies for the Development of the Enantioselective Inverse‐electron‐demand Hetero‐Diels‐Alder Reaction

Víctor Laina‐Martín, Jose A. Fernández‐Salas, José Alemán

Chemistry – A European Journal > 27 > 49 > 12509 - 12520

Cycloaddition reactions, in particular Diels‐Alder reactions, have attracted a lot of attention from organic chemists since they represent one of the most powerful methodologies for the construction of carbon‐carbon bonds. In particular, inverse‐electron‐demand hetero‐Diels‐Alder reactions have been an important breakthrough for the synthesis of heterocyclic compounds. Among all their variants, the...

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Enantioselective Organocatalyzed aza‐Michael Addition Reaction of 2‐Hydroxybenzophenone Imines to Nitroolefins under Batch and Flow Conditions

Andrea Guerrero‐Corella, Miguel A. Valle‐Amores, Alberto Fraile, José Alemán

Advanced Synthesis & Catalysis > 363 > 15 > 3845 - 3851

Herein, an asymmetric organocatalytic aza‐Michael addition reaction of ketimines to nitroolefins is presented. The use of 2‐hydroxybenzophenone imine improves the enantioselective addition of N‐centered nucleophiles to nitroalkenes by means of intramolecular hydrogen bond formation at the imine moiety. Moreover, the versatility of the process is demonstrated under both batch and flow conditions, showing...

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Recent Visible Light and Metal Free Strategies in [2+2] and [4+2] Photocycloadditions

Marina Sicignano, Ricardo I. Rodríguez, José Alemán

European Journal of Organic Chemistry > 2021 > 22 > 3303 - 3321

When aiming to synthesize molecules with elevated molecular complexity starting from relatively simple starting materials, photochemical transformations represent an open avenue to circumvent analogous multistep procedures. Specifically, light‐mediated cycloadditions remain as powerful tools to generate new bonds begotten from non‐very intuitive disconnections, that alternative thermal protocols would...

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Light‐Driven Enantioselective Synthesis of Pyrroline Derivatives by a Radical/Polar Cascade Reaction

Ricardo I. Rodríguez, Leonardo Mollari, José Alemán

Angewandte Chemie > 133 > 9 > 4605 - 4610

Herein, a light‐driven, atom‐economical process that provides access to enantiomerically enriched substituted chiral 1‐pyrroline derivatives is introduced. The strategy involves the distal functionalization of acyl heterocycles through a hydrogen‐atom transfer (HAT) process and the use of tailor‐made ketimines as reliable electrophilic partners. This transformation is translated into an enantiomerically...

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Light‐Driven Enantioselective Synthesis of Pyrroline Derivatives by a Radical/Polar Cascade Reaction

Ricardo I. Rodríguez, Leonardo Mollari, José Alemán

Angewandte Chemie International Edition > 60 > 9 > 4555 - 4560

Herein, a light‐driven, atom‐economical process that provides access to enantiomerically enriched substituted chiral 1‐pyrroline derivatives is introduced. The strategy involves the distal functionalization of acyl heterocycles through a hydrogen‐atom transfer (HAT) process and the use of tailor‐made ketimines as reliable electrophilic partners. This transformation is translated into an enantiomerically...

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On‐Surface Driven Formal Michael Addition Produces m‐Polyaniline Oligomers on Pt(111)

Nerea Ruiz del Árbol, Carlos Sánchez‐Sánchez, Gonzalo Otero‐Irurueta, José I. Martínez, more

Angewandte Chemie International Edition > 59 > 51 > 23220 - 23227

On‐surface synthesis is emerging as a highly rational bottom‐up methodology for the synthesis of molecular structures that are unattainable or complex to obtain by wet chemistry. Here, oligomers of meta‐polyaniline, a known ferromagnetic polymer, were synthesized from para‐aminophenol building‐blocks via an unexpected and highly specific on‐surface formal 1,4 Michael‐type addition at the meta position,...

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On‐Surface Driven Formal Michael Addition Produces m‐Polyaniline Oligomers on Pt(111)

Nerea Ruiz del Árbol, Carlos Sánchez‐Sánchez, Gonzalo Otero‐Irurueta, José I. Martínez, more

Angewandte Chemie > 132 > 51 > 23420 - 23427

On‐surface synthesis is emerging as a highly rational bottom‐up methodology for the synthesis of molecular structures that are unattainable or complex to obtain by wet chemistry. Here, oligomers of meta‐polyaniline, a known ferromagnetic polymer, were synthesized from para‐aminophenol building‐blocks via an unexpected and highly specific on‐surface formal 1,4 Michael‐type addition at the meta position,...

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Visible Light Photocatalytic Synthesis of Tetrahydroquinolines Under Batch and Flow Conditions

Daniel González‐Muñoz, José Luis Nova‐Fernández, Ada Martinelli, Gustavo Pascual‐Coca, more

European Journal of Organic Chemistry > 2020 > 37 > 5995 - 5999

In this work, we describe the use of visible light and a photocatalytic system for the cyclization of iodoaryl vinyl derivatives to tetrahydroquinoline structures. The reaction proceeds under very mild conditions, tolerates different functional groups and more importantly, the method allows the synthesis of N‐free tetrahydroquinolines from N‐unprotected starting materials. In addition, the reaction...

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Boron Dipyrromethene (BODIPY) as Electron‐Withdrawing Group in Asymmetric Copper‐Catalyzed [3+2] Cycloadditions for the Synthesis of Pyrrolidine‐Based Biological Sensors

Thomas Rigotti, Juan Asenjo‐Pascual, Ana Martín‐Somer, Paula Milán Rois, more

Advanced Synthesis & Catalysis > 362 > 6 > 1345 - 1355

In this work, we describe the use of Boron Dipyrromethene (BODIPY) as electron‐withdrawing group for activation of double bonds in asymmetric copper‐catalyzed [3+2] cycloaddition reactions with azomethine ylides. The reactions take place under smooth conditions and with high enantiomeric excess for a large number of different substituents, pointing out the high activation of the alkene by using a...

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Enantioselective Conjugate Azidation of α,β‐Unsaturated Ketones under Bifunctional Organocatalysis by Direct Activation of TMSN₃

Jorge Humbrías‐Martín, M. Carmen Pérez‐Aguilar, Rubén Mas‐Ballesté, Antonella Dentoni Litta, more

Advanced Synthesis & Catalysis > 361 > 20 > 4790 - 4796

An enantioselective organocatalytic conjugate azidation of α,β‐unsaturated ketones is presented. A bifunctional organocatalyst activates TMSN₃, triggering the nucleophilic addition of the azido group to enones in absence of external promoters and avoiding the direct use or the pre‐formation of highly toxic and explosive hydrazoic acid. This protocol proceeds with excellent enantiocontrol under mild...

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Role of intramolecular hydrogen bonds and electron withdrawing groups in the acidity of aldimines and ketimines: a density functional theory study

Fernando Aguilar-Galindo, Ana María Tuñón, Alberto Fraile, José Alemán, more

Theoretical Chemistry Accounts > 2019 > 138 > 4 > 1-16

The role of intramolecular hydrogen bonds and the presence of electron withdrawing groups in the acidity of secondary aldimines and secondary ketimines is investigated by means of density functional theory simulations. We have found that the presence of an intramolecular hydrogen bond can increase the acidity up to ~ 20 kJ mol⁻¹ with respect to structural isomers not showing it. In general, the excess...

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Search results for: José Alemán

Defects and Disorder in Covalent Organic Frameworks for Advanced Applications

Enhancing the Photocatalytic Activity via Direct Covalent Functionalization in Single‐Walled Carbon Nanotubes

Rapid and Safe Continuous‐Flow Simmons‐Smith Cyclopropanation using a Zn/Cu Couple Column

Recent Advances in the Use of Covalent Organic Frameworks as Heterogenous Photocatalysts in Organic Synthesis

Nickel‐Catalysed Cross‐Electrophile Coupling of Benzyl Bromides and Sulfonium Salts towards the Synthesis of Dihydrostilbenes

Remote Giese Radical Addition by Photocatalytic Ring Opening of Activated Cycloalkanols

Fluorinated Sulfinates as Source of Alkyl Radicals in the Photo‐Enantiocontrolled β‐Functionalization of Enals

Fluorinated Sulfinates as Source of Alkyl Radicals in the Photo‐Enantiocontrolled β‐Functionalization of Enals

Frontispiece: Organocatalytic Strategies for the Development of the Enantioselective Inverse‐electron‐demand Hetero‐Diels‐Alder Reaction

Organocatalytic Strategies for the Development of the Enantioselective Inverse‐electron‐demand Hetero‐Diels‐Alder Reaction

Enantioselective Organocatalyzed aza‐Michael Addition Reaction of 2‐Hydroxybenzophenone Imines to Nitroolefins under Batch and Flow Conditions

Recent Visible Light and Metal Free Strategies in [2+2] and [4+2] Photocycloadditions

Light‐Driven Enantioselective Synthesis of Pyrroline Derivatives by a Radical/Polar Cascade Reaction

Light‐Driven Enantioselective Synthesis of Pyrroline Derivatives by a Radical/Polar Cascade Reaction

On‐Surface Driven Formal Michael Addition Produces m‐Polyaniline Oligomers on Pt(111)

On‐Surface Driven Formal Michael Addition Produces m‐Polyaniline Oligomers on Pt(111)

Visible Light Photocatalytic Synthesis of Tetrahydroquinolines Under Batch and Flow Conditions

Boron Dipyrromethene (BODIPY) as Electron‐Withdrawing Group in Asymmetric Copper‐Catalyzed [3+2] Cycloadditions for the Synthesis of Pyrrolidine‐Based Biological Sensors

Enantioselective Conjugate Azidation of α,β‐Unsaturated Ketones under Bifunctional Organocatalysis by Direct Activation of TMSN₃

Role of intramolecular hydrogen bonds and electron withdrawing groups in the acidity of aldimines and ketimines: a density functional theory study

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