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Papers by Romina Vanesa Gómez
Macromolecules, Nov 10, 2009
Polyhydroxy [n]-polyurethanes with chains formed by sugar-derived units have been synthesized. Th... more Polyhydroxy [n]-polyurethanes with chains formed by sugar-derived units have been synthesized. The enantiomerically pure monomeric precursor 1-amino-1-deoxy-2,3:4,5-di-O-isopropylidene-D-galactitol (4) was prepared from D-galactono-1,4-lactone (1) by a three-step route. Acetonation of 1 with 2,2-dimethoxypropane gave methyl 2,3:4,5-di-O-isopropyldene-D-galactonate (2). The ester group of 2 was converted into the amide and reduced with LiA1H 4 to afford 4. This amino alditol was treated with di-tert-butyltricarbonate to produce the intermediate isocyanate derivative as activated monomer for the polymerization. The reaction conditions were adjusted to prevent the formation of urea linkages during the polycondensation. Thus, polymerization of the isocyanate monomer in THF and in the presence of Zr(acac) 4 as catalyst afforded the linear [n]-polyurethane 6, which upon purification was practically free of urea linkages. Removal of the acetal protecting groups of 6 with 10:1 TFA-water, under conditions that did not produce hydrolysis of the polymer chain, led to the polyhydroxy [n]-polyurethane 8, having all the hydroxyl groups free. Polyurethanes 6 and 8 are examples of polyhydroxy [n]-polyurethanes entirely obtained from a sugar precursor. They were isolated as crystalline materials that exhibited high melting temperatures and thermal stability up to 230 °C. Accordingly, the SEM analysis of 6 and 8 revealed surfaces with morphologies characteristic of crystalline polymers.
Tetrahedron: Asymmetry, 2007
Abstract Two regioisomeric and stereoregular AABB-type polyamides have been synthesized using l -... more Abstract Two regioisomeric and stereoregular AABB-type polyamides have been synthesized using l -glutamic acid 1 and l -alaninol 4 as sources of chirality. From 4 , two derivatives of chiral diamines were prepared and regioselectively condensed with pentachlorophenyl 5-oxo-( S )-2-tetrahydrofurancarboxylate 3 , derived from 1 . Manipulation of functional groups and convenient deprotections led to the ammonium salts of N -[1′-amino-( S )-2′-propyl]- and N -[( S )-2′-amino-1′-propyl]-5-oxo-( S )-2-tetrahydrofurancarboxyamide 11 and 15 , respectively, in which the building blocks derived from 1 and 4 are linked through an amido group. Compounds 11 and 15 are, in fact, α,ω-amino acids having amino and lactone groups, and hence activated for polycondensation. Thus, polymerization of 11 took place under regio- and stereo-control to afford stereoregular poly[ N -(1′-amino-( S )-2′-propyl)-carboxyamido-( S )-2-hydroxypentan-5-oic acid] ( 16 ). Similar polycondensation of 15 , under the optimized conditions employed for the synthesis of 16 , gave the regioisomeric polyamide 17 , which exhibited a molecular weight lower than that of 16 . The thermal and spectroscopic properties of optically active AABB-polyamides 16 and 17 are described.
![Research paper thumbnail of Synthesis of Polyhydroxy [n]-Polyurethanes Derived from a Carbohydrate Precursor](https://attachments.academia-assets.com/111505592/thumbnails/1.jpg)
](Macromolecules, 2009
Polyhydroxy [n]-polyurethanes with chains formed by sugar-derived units have been synthesized. Th... more Polyhydroxy [n]-polyurethanes with chains formed by sugar-derived units have been synthesized. The enantiomerically pure monomeric precursor 1-amino-1-deoxy-2,3:4,5-di-O-isopropylidene-Dgalactitol (4) was prepared from D-galactono-1,4-lactone (1) by a three-step route. Acetonation of 1 with 2,2-dimethoxypropane gave methyl 2,3:4,5-di-O-isopropyldene-D-galactonate (2). The ester group of 2 was converted into the amide and reduced with LiAlH 4 to afford 4. This amino alditol was treated with di-tertbutyltricarbonate to produce the intermediate isocyanate derivative as activated monomer for the polymerization. The reaction conditions were adjusted to prevent the formation of urea linkages during the polycondensation. Thus, polymerization of the isocyanate monomer in THF and in the presence of Zr(acac) 4 as catalyst afforded the linear [n]-polyurethane 6, which upon purification was practically free of urea linkages. Removal of the acetal protecting groups of 6 with 10:1 TFA-water, under conditions that did not produce hydrolysis of the polymer chain, led to the polyhydroxy [n]-polyurethane 8, having all the hydroxyl groups free. Polyurethanes 6 and 8 are examples of polyhydroxy [n]-polyurethanes entirely obtained from a sugar precursor. They were isolated as crystalline materials that exhibited high melting temperatures and thermal stability up to 230°C. Accordingly, the SEM analysis of 6 and 8 revealed surfaces with morphologies characteristic of crystalline polymers.
Arkivoc, 2003
The chiral monomer N-(1´-amino-2´-(S)-propyl)-5-oxo-2-(S)-tetrahydrofurancarboxy-amide hydrochlor... more The chiral monomer N-(1´-amino-2´-(S)-propyl)-5-oxo-2-(S)-tetrahydrofurancarboxy-amide hydrochloride (11), a precursor of a AABB-type stereoregular polyamide, has been synthesized from pentachlorophenyl 5-oxo-2-(S)-tetrahydrofurancarboxylate (2) and 2-(S)-amino-1-propanol (3). Compounds 2 and 3 are derivatives of the natural amino acids L-glutamic acid and L-alanine, respectively. The regioselective attack of the amino group of 3 to the ester function of 2 led to N-(1´-hydroxy-2´-(S)-propyl)-5-oxo-tetrahydrofurancarboxyamide (4) in 80% yield. However, the tosylation of the primary hydroxyl group of 4, and the subsequent substitution by azide to give 6, took place with low yields. Therefore, an alternative route was conducted starting from 3, which was selectively N-protected as the tert-butyloxycarbonyl derivative (N-Boc), O-tosylated and substituted by azide to afford 1-azido-2-(S)-N-(tert-butyloxycarbonyl)aminopropane (9) in 41% yield from 3. The amino group of 9 was deprotected by acid hydrolysis and the resulting amine 10 was regioselectively condensed with 2 to give the azide derivative 6. Hydrogenolysis of 6 afforded the desired monomer 11 in 69% yield from 2 and 10.
Carbohydrate Research, 2006
2-Amino-2,3-dideoxy-D D-manno-heptonic acid (7) has been synthesized from 2,5,6,7-tetra-O-acetyl-... more 2-Amino-2,3-dideoxy-D D-manno-heptonic acid (7) has been synthesized from 2,5,6,7-tetra-O-acetyl-3-deoxy-D D-gluco-heptono-1,4-lactone (1), which was readily prepared from D D-glycero-D D-gulo-heptono-1,4-lactone. O-Deacetylation of 1 followed by treatment with 13:1 (v/v) 2,2-dimethoxypropane/acetone in the presence of p-toluenesulfonic acid gave methyl 3-deoxy-4,5:6,7di-O-isopropylidene-D D-gluco-heptonate (3) as a crystalline product (80% yield). The free hydroxyl group (OH-2) of 3 was mesylated and substituted by azide to give the corresponding azide derivative 5. Hydrogenolysis and further hydrolysis of the ester function of 5 afforded a-amino acid 7 (43% overall yield from 1). Compound 7 is an analog of L L-alanine having a polyhydroxy chain attached to C-3. The diastereoisomer of 7 at C-2, 2-amino-2,3-dideoxy-D D-gluco-heptonic acid (12) was also prepared from 3, by a route that involved 2,3-dideoxy-2-iodo derivative 8 as a key intermediate.
Existe abundante literatura en la que se abordan las creencias de los profesores de segunda lengu... more Existe abundante literatura en la que se abordan las creencias de los profesores de segunda lengua (L2) o lengua extranjera (LE). Sin embargo, son pocos los estudios sobre este tema que consideran a los profesores de L2/LE en formación. El objetivo de este estudio es conocer las creencias que tienen futuros profesores de inglés respecto a las competencias que debieran identificar a los profesores de inglés como lengua extranjera (ILE) en Chile. Tres dominios de competencia están bajo escrutinio: (1) lengua y cultura inglesas, (2) didáctica de la enseñanza y (3) actitudinal-profesional. Se utilizó un cuestionario tipo Likert para recopilar datos de futuros docentes de ILE (N=208) que cursan primer (N=129) y cuarto año (N=79) de cuatro universidades chilenas. Los resultados generales muestran que el domino de competencia que los futuros profesores consideran más importante es el actitudinal-profesional, especialmente los participantes de cuarto año.
Literatura y Lingüística, 2018
Los futuros profesores de inglés en Chile deben, durante su formación, alcanzar un alto dominio d... more Los futuros profesores de inglés en Chile deben, durante su formación, alcanzar un alto dominio de competencia comunicativa. Este artículo da cuenta de errores gramaticales cometidos en discurso escrito por futuros profesores de inglés, en contexto de inglés como lengua extranjera, de distintos niveles de su plan curricular. Los resultados señalan que existen diferencias en el número y tipo de error cometidos por los sujetos de los distintosniveles, mostrando una mayor diferencia entre los sujetos de primer y cuarto año. Esto permite describir su estado de interlengua.
REIRE. Revista d'Innovaci� i Recerca en Educaci�, 2018
Basado en Equipos es una metodología que ha sido utilizada con éxito en educación superior. Esta ... more Basado en Equipos es una metodología que ha sido utilizada con éxito en educación superior. Esta facilita el aprendizaje activo de los estudiantes y la diversificación de la enseñanza de los docentes. MÉTODO. En este contexto, este artículo presenta una experiencia en la cual la metodología Aprendizaje Basado en Equipos se aplica a un grupo numeroso de estudiantes que cursan una asignatura de una carrera universitaria para evaluar su efectividad, tanto en la enseñanza, como en el logro de aprendizajes profundos. RESULTADOS. Los resultados obtenidos dan cuenta de que esta metodología, por un lado, propició el aprendizaje profundo, puesto que el 68% de los estudiantes abordó la asignatura, según Study Process Questionnaire, desde un enfoque profundo de aprendizaje y, por otro lado, promovió experiencias favorables de aprendizaje, lo que se evidencia en el índice general de las cuatro dimensiones consideradas para su evaluación (buena enseñanza, metas claras, carga de trabajo y evaluación apropiada), el cual fue de 74 en un índice del 1 al 100. DISCUSIÓN. Los hallazgos se discuten sobre la base del modelo de Presagio, Proceso y Producto para medir la efectividad de la metodología empleada. //Palabras clave Aprendizaje Basado en Equipos; Enfoques de aprendizaje; Experiencias de innovación en educación superior; Educación universitaria.
Macromolecules, Nov 10, 2009
Polyhydroxy [n]-polyurethanes with chains formed by sugar-derived units have been synthesized. Th... more Polyhydroxy [n]-polyurethanes with chains formed by sugar-derived units have been synthesized. The enantiomerically pure monomeric precursor 1-amino-1-deoxy-2,3:4,5-di-O-isopropylidene-D-galactitol (4) was prepared from D-galactono-1,4-lactone (1) by a three-step route. Acetonation of 1 with 2,2-dimethoxypropane gave methyl 2,3:4,5-di-O-isopropyldene-D-galactonate (2). The ester group of 2 was converted into the amide and reduced with LiA1H 4 to afford 4. This amino alditol was treated with di-tert-butyltricarbonate to produce the intermediate isocyanate derivative as activated monomer for the polymerization. The reaction conditions were adjusted to prevent the formation of urea linkages during the polycondensation. Thus, polymerization of the isocyanate monomer in THF and in the presence of Zr(acac) 4 as catalyst afforded the linear [n]-polyurethane 6, which upon purification was practically free of urea linkages. Removal of the acetal protecting groups of 6 with 10:1 TFA-water, under conditions that did not produce hydrolysis of the polymer chain, led to the polyhydroxy [n]-polyurethane 8, having all the hydroxyl groups free. Polyurethanes 6 and 8 are examples of polyhydroxy [n]-polyurethanes entirely obtained from a sugar precursor. They were isolated as crystalline materials that exhibited high melting temperatures and thermal stability up to 230 °C. Accordingly, the SEM analysis of 6 and 8 revealed surfaces with morphologies characteristic of crystalline polymers.
Tetrahedron: Asymmetry, 2007
Abstract Two regioisomeric and stereoregular AABB-type polyamides have been synthesized using l -... more Abstract Two regioisomeric and stereoregular AABB-type polyamides have been synthesized using l -glutamic acid 1 and l -alaninol 4 as sources of chirality. From 4 , two derivatives of chiral diamines were prepared and regioselectively condensed with pentachlorophenyl 5-oxo-( S )-2-tetrahydrofurancarboxylate 3 , derived from 1 . Manipulation of functional groups and convenient deprotections led to the ammonium salts of N -[1′-amino-( S )-2′-propyl]- and N -[( S )-2′-amino-1′-propyl]-5-oxo-( S )-2-tetrahydrofurancarboxyamide 11 and 15 , respectively, in which the building blocks derived from 1 and 4 are linked through an amido group. Compounds 11 and 15 are, in fact, α,ω-amino acids having amino and lactone groups, and hence activated for polycondensation. Thus, polymerization of 11 took place under regio- and stereo-control to afford stereoregular poly[ N -(1′-amino-( S )-2′-propyl)-carboxyamido-( S )-2-hydroxypentan-5-oic acid] ( 16 ). Similar polycondensation of 15 , under the optimized conditions employed for the synthesis of 16 , gave the regioisomeric polyamide 17 , which exhibited a molecular weight lower than that of 16 . The thermal and spectroscopic properties of optically active AABB-polyamides 16 and 17 are described.
Macromolecules, 2009
Polyhydroxy [n]-polyurethanes with chains formed by sugar-derived units have been synthesized. Th... more Polyhydroxy [n]-polyurethanes with chains formed by sugar-derived units have been synthesized. The enantiomerically pure monomeric precursor 1-amino-1-deoxy-2,3:4,5-di-O-isopropylidene-Dgalactitol (4) was prepared from D-galactono-1,4-lactone (1) by a three-step route. Acetonation of 1 with 2,2-dimethoxypropane gave methyl 2,3:4,5-di-O-isopropyldene-D-galactonate (2). The ester group of 2 was converted into the amide and reduced with LiAlH 4 to afford 4. This amino alditol was treated with di-tertbutyltricarbonate to produce the intermediate isocyanate derivative as activated monomer for the polymerization. The reaction conditions were adjusted to prevent the formation of urea linkages during the polycondensation. Thus, polymerization of the isocyanate monomer in THF and in the presence of Zr(acac) 4 as catalyst afforded the linear [n]-polyurethane 6, which upon purification was practically free of urea linkages. Removal of the acetal protecting groups of 6 with 10:1 TFA-water, under conditions that did not produce hydrolysis of the polymer chain, led to the polyhydroxy [n]-polyurethane 8, having all the hydroxyl groups free. Polyurethanes 6 and 8 are examples of polyhydroxy [n]-polyurethanes entirely obtained from a sugar precursor. They were isolated as crystalline materials that exhibited high melting temperatures and thermal stability up to 230°C. Accordingly, the SEM analysis of 6 and 8 revealed surfaces with morphologies characteristic of crystalline polymers.
Arkivoc, 2003
The chiral monomer N-(1´-amino-2´-(S)-propyl)-5-oxo-2-(S)-tetrahydrofurancarboxy-amide hydrochlor... more The chiral monomer N-(1´-amino-2´-(S)-propyl)-5-oxo-2-(S)-tetrahydrofurancarboxy-amide hydrochloride (11), a precursor of a AABB-type stereoregular polyamide, has been synthesized from pentachlorophenyl 5-oxo-2-(S)-tetrahydrofurancarboxylate (2) and 2-(S)-amino-1-propanol (3). Compounds 2 and 3 are derivatives of the natural amino acids L-glutamic acid and L-alanine, respectively. The regioselective attack of the amino group of 3 to the ester function of 2 led to N-(1´-hydroxy-2´-(S)-propyl)-5-oxo-tetrahydrofurancarboxyamide (4) in 80% yield. However, the tosylation of the primary hydroxyl group of 4, and the subsequent substitution by azide to give 6, took place with low yields. Therefore, an alternative route was conducted starting from 3, which was selectively N-protected as the tert-butyloxycarbonyl derivative (N-Boc), O-tosylated and substituted by azide to afford 1-azido-2-(S)-N-(tert-butyloxycarbonyl)aminopropane (9) in 41% yield from 3. The amino group of 9 was deprotected by acid hydrolysis and the resulting amine 10 was regioselectively condensed with 2 to give the azide derivative 6. Hydrogenolysis of 6 afforded the desired monomer 11 in 69% yield from 2 and 10.
Carbohydrate Research, 2006
2-Amino-2,3-dideoxy-D D-manno-heptonic acid (7) has been synthesized from 2,5,6,7-tetra-O-acetyl-... more 2-Amino-2,3-dideoxy-D D-manno-heptonic acid (7) has been synthesized from 2,5,6,7-tetra-O-acetyl-3-deoxy-D D-gluco-heptono-1,4-lactone (1), which was readily prepared from D D-glycero-D D-gulo-heptono-1,4-lactone. O-Deacetylation of 1 followed by treatment with 13:1 (v/v) 2,2-dimethoxypropane/acetone in the presence of p-toluenesulfonic acid gave methyl 3-deoxy-4,5:6,7di-O-isopropylidene-D D-gluco-heptonate (3) as a crystalline product (80% yield). The free hydroxyl group (OH-2) of 3 was mesylated and substituted by azide to give the corresponding azide derivative 5. Hydrogenolysis and further hydrolysis of the ester function of 5 afforded a-amino acid 7 (43% overall yield from 1). Compound 7 is an analog of L L-alanine having a polyhydroxy chain attached to C-3. The diastereoisomer of 7 at C-2, 2-amino-2,3-dideoxy-D D-gluco-heptonic acid (12) was also prepared from 3, by a route that involved 2,3-dideoxy-2-iodo derivative 8 as a key intermediate.
Existe abundante literatura en la que se abordan las creencias de los profesores de segunda lengu... more Existe abundante literatura en la que se abordan las creencias de los profesores de segunda lengua (L2) o lengua extranjera (LE). Sin embargo, son pocos los estudios sobre este tema que consideran a los profesores de L2/LE en formación. El objetivo de este estudio es conocer las creencias que tienen futuros profesores de inglés respecto a las competencias que debieran identificar a los profesores de inglés como lengua extranjera (ILE) en Chile. Tres dominios de competencia están bajo escrutinio: (1) lengua y cultura inglesas, (2) didáctica de la enseñanza y (3) actitudinal-profesional. Se utilizó un cuestionario tipo Likert para recopilar datos de futuros docentes de ILE (N=208) que cursan primer (N=129) y cuarto año (N=79) de cuatro universidades chilenas. Los resultados generales muestran que el domino de competencia que los futuros profesores consideran más importante es el actitudinal-profesional, especialmente los participantes de cuarto año.
Literatura y Lingüística, 2018
Los futuros profesores de inglés en Chile deben, durante su formación, alcanzar un alto dominio d... more Los futuros profesores de inglés en Chile deben, durante su formación, alcanzar un alto dominio de competencia comunicativa. Este artículo da cuenta de errores gramaticales cometidos en discurso escrito por futuros profesores de inglés, en contexto de inglés como lengua extranjera, de distintos niveles de su plan curricular. Los resultados señalan que existen diferencias en el número y tipo de error cometidos por los sujetos de los distintosniveles, mostrando una mayor diferencia entre los sujetos de primer y cuarto año. Esto permite describir su estado de interlengua.
REIRE. Revista d'Innovaci� i Recerca en Educaci�, 2018
Basado en Equipos es una metodología que ha sido utilizada con éxito en educación superior. Esta ... more Basado en Equipos es una metodología que ha sido utilizada con éxito en educación superior. Esta facilita el aprendizaje activo de los estudiantes y la diversificación de la enseñanza de los docentes. MÉTODO. En este contexto, este artículo presenta una experiencia en la cual la metodología Aprendizaje Basado en Equipos se aplica a un grupo numeroso de estudiantes que cursan una asignatura de una carrera universitaria para evaluar su efectividad, tanto en la enseñanza, como en el logro de aprendizajes profundos. RESULTADOS. Los resultados obtenidos dan cuenta de que esta metodología, por un lado, propició el aprendizaje profundo, puesto que el 68% de los estudiantes abordó la asignatura, según Study Process Questionnaire, desde un enfoque profundo de aprendizaje y, por otro lado, promovió experiencias favorables de aprendizaje, lo que se evidencia en el índice general de las cuatro dimensiones consideradas para su evaluación (buena enseñanza, metas claras, carga de trabajo y evaluación apropiada), el cual fue de 74 en un índice del 1 al 100. DISCUSIÓN. Los hallazgos se discuten sobre la base del modelo de Presagio, Proceso y Producto para medir la efectividad de la metodología empleada. //Palabras clave Aprendizaje Basado en Equipos; Enfoques de aprendizaje; Experiencias de innovación en educación superior; Educación universitaria.