Search results for: Alejandro Parra

Items from 1 to 20 out of 42 results

article

Enantiospecific Synthesis of 1,3‐Disubstituted Allenes from Propargylic Carbonates through a Borylation‐1,2‐Elimination Process

Carlos Jarava‐Barrera, Alejandro Parra, Sergio Quesada, Sergio Orgaz‐Gordillo, more

Advanced Synthesis & Catalysis > 366 > 4 > 768 - 773

An array of enantioenriched vinyl boronates bearing an allylic carbonate moiety have been prepared through selective hydroboration of propargyl carbonates. Treatment of these vinyl boronates with TBAF in THF affords enantioenriched 1,3‐disubstituted allenes through a novel 1,2‐anti elimination in good yields and high enantiospecificities.

article

Lamb–Shaffer syndrome: 20 Spanish patients and literature review expands the view of neurodevelopmental disorders caused by SOX5 haploinsufficiency

Jair Tenorio‐Castano, Ángela Sánchez‐Algaba Gómez, Mónica Coronado, Pilar Rodríguez‐Martín, more

Clinical Genetics > 104 > 6 > 637 - 647

Lamb–Shaffer Syndrome (LSS; OMIM #616803; ORPHA #313892; ORPHA #313884) is an infrequent genetic disorder that affects multiple aspects of human development especially those related to the development of the nervous system. LSS is caused by variants in the SOX5 gene. At the molecular level, SOX5 gene encodes for a transcription factor containing a High Mobility Group (HMG) DNA‐Binding domain with...

article

Adult experiences in Beckwith–Wiedemann syndrome

William A. Drust, Alessandro Mussa, Andrea Gazzin, Pablo Lapunzina, more

American Journal of Medical Genetics Part C: Seminars in Medical Genetics > 193 > 2 > 116 - 127

Beckwith–Wiedemann syndrome (BWS) is an overgrowth and epigenetic disorder caused by changes on chromosome 11p15. The primary features requiring management in childhood include macroglossia, omphalocele, lateralized overgrowth, hyperinsulinism, and embryonal tumors. Management guidelines have not been developed for adults with BWS and there have been few studies to assess the clinical needs of these...

article

Stereoselective Diboration of Spirocyclobutenes: A Platform for the Synthesis of Spirocycles with Orthogonal Exit Vectors

Luis Nóvoa, Laura Trulli, Alejandro Parra, Mariola Tortosa

Angewandte Chemie International Edition > 60 > 21 > 11763 - 11768

The diastereo‐ and enantioselective diboration of spirocyclobutenes provides a platform for the rapid preparation of a wide variety of chiral spirocyclic building blocks. The chemoselective functionalization of the carbon‐boron bond in the products, including a stereospecific sp³‐sp² Suzuki–Miyaura cross‐coupling reaction, provides a powerful tool to control the directionality and the nature of the...

article

Stereoselective Diboration of Spirocyclobutenes: A Platform for the Synthesis of Spirocycles with Orthogonal Exit Vectors

Luis Nóvoa, Laura Trulli, Alejandro Parra, Mariola Tortosa

Angewandte Chemie > 133 > 21 > 11869 - 11874

article

Atypical erythema nodosum in a patient with COVID‐19 pneumonia

Lucia Ordieres‐Ortega, Neera Toledo‐Samaniego, Alejandro Parra‐Virto, Eduardo Fernández‐Carracedo, more

Dermatologic Therapy > 33 > 4 > n/a - n/a

article

Stereospecific Synthesis of α‐Hydroxy‐Cyclopropylboronates from Allylic Epoxides

Laura Amenós, Laura Trulli, Luis Nóvoa, Alejandro Parra, more

Angewandte Chemie International Edition > 58 > 10 > 3188 - 3192

Herein, we report a catalytic and stereospecific method for the preparation of enantioenriched α‐hydroxy cyclopropylboronates with control in four contiguous stereocenters. The reaction involves the borylation of readily available allylic epoxides using an inexpensive Cu(I) salt and a commercially available phosphine ligand. High diastereocontrol is achieved and different diastereomers can be selectively...

article

Stereospecific Synthesis of α‐Hydroxy‐Cyclopropylboronates from Allylic Epoxides

Laura Amenós, Laura Trulli, Luis Nóvoa, Alejandro Parra, more

Angewandte Chemie > 131 > 10 > 3220 - 3224

article

Stereoselective Traceless Borylation–Allenation of Propargylic Epoxides: Dual Role of the Copper Catalyst

Carlos Jarava‐Barrera, Alejandro Parra, Laura Amenós, Ana Arroyo, more

Chemistry – A European Journal > 23 > 69 > 17478 - 17481

Chiral α‐allenols are prepared with high diastereocontrol through an unprecedented and spontaneous β‐oxygen elimination of an α‐epoxy vinyl boronate. Stochiometric experiments and DFT calculations support a dual role of the copper catalyst, which orchestrates the hydroboration and the syn‐elimination step.

article

Modelling and projecting the response of local assemblage composition to land use change across Colombia

Susy Echeverría‐Londoño, Tim Newbold, Lawrence N. Hudson, Sara Contu, more

Diversity and Distributions > 22 > 11 > 1099 - 1111

AimUnderstanding the impact of land use change within assemblages is fundamental to mitigation policies at local and regional scale. Here, we aim to quantify how site‐level terrestrial assemblages are responding to land use change in Colombia a mega‐diverse country and to project future biodiversity under different scenarios of land use change associated with climate change policies. LocationColombia...

article

Enantioselective Synthesis of Cyclobutylboronates via a Copper‐Catalyzed Desymmetrization Approach

Manuel Guisán‐Ceinos, Alejandro Parra, Víctor Martín‐Heras, Mariola Tortosa

Angewandte Chemie > 128 > 24 > 7083 - 7086

The first catalytic enantioselective synthesis of cyclobutylboronates, by using a chiral copper(I) complex, is reported. A broad variety of cyclobutanes have been prepared with consistently high levels of diastereo‐ and enantiocontrol. Moreover, this method constitutes the first report of an enantioselective desymmetrization of meso‐cyclobutenes to prepare chiral cyclobutanes.

article

Enantioselective Synthesis of Cyclobutylboronates via a Copper‐Catalyzed Desymmetrization Approach

Manuel Guisán‐Ceinos, Alejandro Parra, Víctor Martín‐Heras, Mariola Tortosa

Angewandte Chemie International Edition > 55 > 24 > 6969 - 6972

article

Organocatalytic transformations of alkynals, alkynones, propriolates, and related electron-deficient alkynes

Alberto Fraile, Alejandro Parra, Mariola Tortosa, José Alemán

Tetrahedron > 2014 > 70 > 48 > 9145-9173

chapter

Profile user in moviles healt apps

Diego Alejandro Parra Alvarez, Leonardo Juan Ramirez Lopez

2014 IEEE ANDESCON > 1

2014 IEEE ANDESCON

This research shows the development and implementation of a profiling and exchange system in mobile devices applied to a SOA architecture in a Telehealth center in Colombia. The service is directly targeted at profiling the user with a continuous monitoring of variables to generate health monitoring alarms: amount of kilocalories expend and consumed, heart activity, diets, education, among others...

article

Highly Enantioselective Construction of Tricyclic Derivatives by the Desymmetrization of Cyclohexadienones

Cecilia Martín‐Santos, Carlos Jarava‐Barrera, Sandra del Pozo, Alejandro Parra, more

Angewandte Chemie > 126 > 31 > 8323 - 8328

The asymmetric synthesis of tricyclic compounds by the desymmetrization of cyclohexadienones is presented. The reaction tolerated a large variety of substituents at different positions of the cyclohexadienone, and heterocyclic rings of different sizes were accessible. Density functional theory calculations showed that the reaction proceeds through an asynchronous [4+2] cycloaddition.

article

Highly Enantioselective Construction of Tricyclic Derivatives by the Desymmetrization of Cyclohexadienones

Cecilia Martín‐Santos, Carlos Jarava‐Barrera, Sandra del Pozo, Alejandro Parra, more

Angewandte Chemie International Edition > 53 > 31 > 8184 - 8189

article

Sulfonyl Acetylenes as Alkynylating Reagents Under Radical or Anionic Conditions

José Luis García Ruano, José Alemán, Alejandro Parra, Leyre Marzo

European Journal of Organic Chemistry > 2014 > 8 > 1577 - 1588

We provide a summary of the literature describing the use of β‐substituted sulfonylacetylenes as efficient alkynylation reagents in their reactions with radical or anionic species. Such alkynylation is due to the unexpected behavior of ethynyl sulfones, which undergo “anti‐Michael” addition of radicals and organolithium reagents and subsequent elimination of the sulfinate moiety. The reaction behavior...

article

[8+2] Formal Cycloaddition Reactions of Tropones with Azlactones under Brønsted Acid Catalysis and Synthesis of α‐(2‐Tropyl), α‐Alkyl α‐Amino Acids

Francisco Esteban, Ricardo Alfaro, Francisco Yuste, Alejandro Parra, more

European Journal of Organic Chemistry > 2014 > 7 > 1395 - 1400

The reaction of tropones with azlactones catalyzed by Brønsted acids affords a variety of dihydro‐2H‐cyclohepta[b]furan derivatives, corresponding to a formal [8+2] cycloaddition process. They can easily be opened by nucleophiles to afford a new type of α,α‐disubstituted α‐amino acid (or peptide) containing seven‐membered rings at the quaternary position.

article

Chiral Hypervalent Iodine Reagents: Synthesis and Reactivity

Alejandro Parra, Silvia Reboredo

Chemistry – A European Journal > 19 > 51 > 17244 - 17260

Chiral hypervalent iodine chemistry has been steadily increasing in importance in recent years. This review catalogues enantioselective transformations triggered by chiral hypervalent iodine(III/V) reagents, in stoichiometric or catalytic quantities, highlighting the different reactivities in terms of yield and enantioselectivity. Moreover, the synthesis of the most remarkable and successful catalysts...

article

Synthesis of Alkyl‐Ynol‐Ethers by “Anti‐Michael Addition” of Metal Alkoxides to β‐Substituted Alkynylsulfones

Leyre Marzo, Alejandro Parra, María Frías, José Alemán, more

European Journal of Organic Chemistry > 2013 > 20 > 4405 - 4409

The reaction of metal alkoxides with β‐substituted 2‐(p‐tolylsulfonyl)acetylenes, involving an anti‐Michael addition reaction followed by the in situ elimination of the sulfonyl moiety, provides a direct method for the synthesis of alkyl alkynyl ethers bearing aryl or TIPS groups joined to the triple bond. Arylalkynyl ethers derived from primary alkoxides are in situ hydrolyzed into arylacetic esters.

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INFONA - science communication portal

Search results for: Alejandro Parra

Enantiospecific Synthesis of 1,3‐Disubstituted Allenes from Propargylic Carbonates through a Borylation‐1,2‐Elimination Process

Lamb–Shaffer syndrome: 20 Spanish patients and literature review expands the view of neurodevelopmental disorders caused by SOX5 haploinsufficiency

Adult experiences in Beckwith–Wiedemann syndrome

Stereoselective Diboration of Spirocyclobutenes: A Platform for the Synthesis of Spirocycles with Orthogonal Exit Vectors

Stereoselective Diboration of Spirocyclobutenes: A Platform for the Synthesis of Spirocycles with Orthogonal Exit Vectors

Atypical erythema nodosum in a patient with COVID‐19 pneumonia

Stereospecific Synthesis of α‐Hydroxy‐Cyclopropylboronates from Allylic Epoxides

Stereospecific Synthesis of α‐Hydroxy‐Cyclopropylboronates from Allylic Epoxides

Stereoselective Traceless Borylation–Allenation of Propargylic Epoxides: Dual Role of the Copper Catalyst

Modelling and projecting the response of local assemblage composition to land use change across Colombia

Enantioselective Synthesis of Cyclobutylboronates via a Copper‐Catalyzed Desymmetrization Approach

Enantioselective Synthesis of Cyclobutylboronates via a Copper‐Catalyzed Desymmetrization Approach

Organocatalytic transformations of alkynals, alkynones, propriolates, and related electron-deficient alkynes

Profile user in moviles healt apps

Highly Enantioselective Construction of Tricyclic Derivatives by the Desymmetrization of Cyclohexadienones

Highly Enantioselective Construction of Tricyclic Derivatives by the Desymmetrization of Cyclohexadienones

Sulfonyl Acetylenes as Alkynylating Reagents Under Radical or Anionic Conditions

[8+2] Formal Cycloaddition Reactions of Tropones with Azlactones under Brønsted Acid Catalysis and Synthesis of α‐(2‐Tropyl), α‐Alkyl α‐Amino Acids

Chiral Hypervalent Iodine Reagents: Synthesis and Reactivity

Synthesis of Alkyl‐Ynol‐Ethers by “Anti‐Michael Addition” of Metal Alkoxides to β‐Substituted Alkynylsulfones

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