Marta Fierros - Academia.edu (original) (raw)

Papers by Marta Fierros

Research paper thumbnail of Mucor miehei lipase catalyzed transesterifications on aromatic and heteroaromatic substrates. A general survey

Tetrahedron, 1994

An investigation on Mucor miehei lipase-catalyzed transesterifications of 16 aromatic and hetenxu... more An investigation on Mucor miehei lipase-catalyzed transesterifications of 16 aromatic and hetenxuomatic esters in organic solvents is described. The points studied were the activity and regioselectivity of the enzyme-catalyzed reaction of either one or two ester groups situated in different positions on several heterocyclic systems with an aliphatic alcohol. The reactions took place in moderate to good yields and, in some cases, regi~lectively.

Research paper thumbnail of Intermediates in the synthesis of dipyrazolic podands and ester crowns via regioselective lipase catalyzed hydrolysis of a tetraester

Tetrahedron, 1997

In this work we study the Mucor miehei lipase-catalyzed hidrolysis of 1,3-bis[3,5-bis(ethoxycarbo... more In this work we study the Mucor miehei lipase-catalyzed hidrolysis of 1,3-bis[3,5-bis(ethoxycarbonyl)-1H-pyrazol-1-yl]propane and the potential usefulness of the resulting acids as intermediates in the synthesis of podand and crown esters.

Research paper thumbnail of Regioselective Enzyme-catalyzed Synthesis of Pyrazole-containing Podands

HETEROCYCLES, 1993

Novel enzyme-mediated synthetic routes were developed to provide a new family of sophorolipid der... more Novel enzyme-mediated synthetic routes were developed to provide a new family of sophorolipid derivatives and glycolopid-based amphiphilic monomers. These compounds are of great interest for their potential use in immunoregulation, as well as for other biological properties. In the present work, an efficient lipase-catalyzed conversion of sophorolipid ethyl ester to (a) the 6′-monoacylated derivatives using Novozym 435, (b) 6′′-monoacylated derivatives using Lipase PS-C, (c) secondary amide derivatives using Novozym 435, and (d) 6′,6′′-diacylated amide derivatives using Novozym 435 in an one-pot reaction and (e) the regioselective monoacylation of an amide derivative at the 6′-and 6′′-positions using Novozym 435 and Lipase PS-C, respectively, are described. The ethyl ester produced by esterification of the sophorolipid mixture with sodium ethoxide was subjected to acylation catalyzed by Novozym 435 in dry tetrahedrofuran (THF) with vinyl acetate and vinyl methacrylate to produce 6′-monoacylated derivatives. In contrast, Lipase PS-C catalyzed acylations of sophorolipid ethyl ester in dry THF with vinyl acetate and vinyl methacrylate to give the corresponding 6′-monoacylated derivatives. Novozym 435 mediated amidation of sophorolipid ethyl ester in dry THF with phenethylamine, tyramine, p-methoxyphenethylamine, 2-(p-tolyl)ethylamine, and p-fluorophenethylamine generated the corresponding secondary amides but not tertiary amides. The formation of diacyl derivatives of amides was achieved by their treatment with vinyl acetate and vinyl methacrylate in dry THF using Novozym 435 as catalyst. The conversion of sophorolipid ethyl ester to the same diacyl derivatives of amide (i.e., both amidation and acylation) in high yield was also demonstrated in dry THF by a one-pot reaction using Novozym 435. Furthermore, regioselective monoacylation of a sophorolipid amide at 6′ and 6′′ in dry THF with vinyl acetate and vinyl methacrylate using Novozym 435 and Lipase PS-C was also demonstrated.

Research paper thumbnail of Regioselective lipase-catalyzed synthesis of l-glutamic α-monoamide derivatives. Effect of the N-blocking group

Tetrahedron, 1997

Several Block-L-Glu(OEt)-OEt (Block = amides, carbamates and trityl group) have been subjected to... more Several Block-L-Glu(OEt)-OEt (Block = amides, carbamates and trityl group) have been subjected to an aminolysis reaction catalyzed by the lipase B of Candida antarctica. The reaction took place in a regioselective manner and ot-monoamides were obtained in all cases (except the bulky trityl group that did not react). Besides the synthetic value of the method, the results may empirically point out to some features of the active site of the enzyme as the reaction rate was severely affected by volume and electronic characteristics of the blocking group. © 1997 Elsevier Science Ltd.

Research paper thumbnail of Resolution of 1-(4-amino-3-chloro-5-cyanophenyl)-2-bromo-1-ethanol by lipase mediated enantioselective alcoholysis, hydrolysis and acylation

Tetrahedron-asymmetry, 1998

Resolution of 1-(4-amino-3-chloro-5-cyanophenyl)-2-bromo-1-ethanol has been achieved by ethanol e... more Resolution of 1-(4-amino-3-chloro-5-cyanophenyl)-2-bromo-1-ethanol has been achieved by ethanol enantioselective lipase-catalysed alcoholysis, hydrolysis and acylation. Although a good enantioselectivity was observed in the three reactions, the best results were obtained by hydrolysis. This α-bromohydrin is an intermediate in the synthesis of a new adrenergic agent.

Research paper thumbnail of Selective carriers of norepinephrine and ammonium ions: Ionophoric properties and molecular modelling studies of diester crown compounds containing a 1,3-bis(1 H-pyrazol-1-yl)propane unit

Bioorganic & Medicinal Chemistry, 1997

Ionophoric properties of dipyrazolic crowns and podands containing a 1,3-bis(lH-pyrazol-1-yl)prop... more Ionophoric properties of dipyrazolic crowns and podands containing a 1,3-bis(lH-pyrazol-1-yl)propane unit in their structure are described. They show selectivity of ammonium vs alkali cations and interesting norepinephrine transport rates. A molecular modelling study has been used to elucidate the superstructures of the crown and ammonium cation complexes. 0 1997, Elsevier Science Ltd. All rights reserved.

Research paper thumbnail of Regioselective Mucor miehei lipase catalyzed synthesis of podands containing a 1,3-bis(1 H-Pyrazol-1-yl)propane unit

Tetrahedron, 1995

The synthesis of podands (acyclic crown ethers) including a 1,3-bis( 1H-pyrazol-1-yl)propane unit... more The synthesis of podands (acyclic crown ethers) including a 1,3-bis( 1H-pyrazol-1-yl)propane unit in their molecule is described. The key step of this synthesis was a regioselective lipase-catalyzed transesterification of the dipyrazolic tetraethylester 1 with monomethylether polyethyleneglycols. The ionophoric properties of the podands 4a-d as carriers of cations were evaluated. Molecular modelling studies and quantum-chemical calculations were used in order to elucidate the superestructtwes of the complexes with ammonium cations.

Research paper thumbnail of First regioselective mucor miehei lipase catalyzed synthesis of diester crowns. New macrocycles containing a 1,3-bis(1H-pyrazol-1-yl)propane unit

Bioorganic & Medicinal Chemistry Letters, 1994

... NEW MACROCYCLES CONTAINING A 1,3-BIS(1H-PYRAZOL-1-YL)PROPANE UNIT Marta Fierros, Maria Isabel... more ... NEW MACROCYCLES CONTAINING A 1,3-BIS(1H-PYRAZOL-1-YL)PROPANE UNIT Marta Fierros, Maria Isabel Rodriguez-Franco, Klar Navarro, and Santiago Conde* Instituto de Qufmica ... 2. Izatt, RM; Bradshaw, JS; Nielsen, SA; Lamb, JD; Christensen, JJ; Sen, S. Chem. Rev. ...

Research paper thumbnail of Regioselective lipase catalyzed synthesis of diester crowns. New asymmetric macrocycles containing a 1,3-bis(1 H-pyrazol-1-yl)propane unit

Tetrahedron, 1997

Several Block-L-Glu(OEt)-OEt (Block = amides, carbamates and trityl group) have been subjected to... more Several Block-L-Glu(OEt)-OEt (Block = amides, carbamates and trityl group) have been subjected to an aminolysis reaction catalyzed by the lipase B of Candida antarctica. The reaction took place in a regioselective manner and ot-monoamides were obtained in all cases (except the bulky trityl group that did not react). Besides the synthetic value of the method, the results may empirically point out to some features of the active site of the enzyme as the reaction rate was severely affected by volume and electronic characteristics of the blocking group. © 1997 Elsevier Science Ltd.

Research paper thumbnail of X-ray Crystallography at 170 K of Racemic 2,2'-Dimethoxy-9,9'-biacridine and 1H NMR Study of 2,2'Diacetoxy9,9'-biacridine

Molecules, 1999

Three derivatives of 9,9'-biacridine, 2,2'-dihydroxy, 2,2'-dimethoxy and 2,2'diacetoxy have been ... more Three derivatives of 9,9'-biacridine, 2,2'-dihydroxy, 2,2'-dimethoxy and 2,2'diacetoxy have been prepared. The crystal structure of racemic 2,2'-dimethoxy-9,9'-biacridine CHCl 3 1:1 complex has been determined and shows an almost perpendicular conformation of both acridine rings. 1 H NMR experiments using the diacetoxy derivative and both Eu(tfc) 3 and R-Pirkle's alcohol show the splitting of some signals characteristic of a racemic compound.

Research paper thumbnail of Mucor miehei lipase catalyzed transesterifications on aromatic and heteroaromatic substrates. A general survey

Tetrahedron, 1994

An investigation on Mucor miehei lipase-catalyzed transesterifications of 16 aromatic and hetenxu... more An investigation on Mucor miehei lipase-catalyzed transesterifications of 16 aromatic and hetenxuomatic esters in organic solvents is described. The points studied were the activity and regioselectivity of the enzyme-catalyzed reaction of either one or two ester groups situated in different positions on several heterocyclic systems with an aliphatic alcohol. The reactions took place in moderate to good yields and, in some cases, regi~lectively.

Research paper thumbnail of Intermediates in the synthesis of dipyrazolic podands and ester crowns via regioselective lipase catalyzed hydrolysis of a tetraester

Tetrahedron, 1997

In this work we study the Mucor miehei lipase-catalyzed hidrolysis of 1,3-bis[3,5-bis(ethoxycarbo... more In this work we study the Mucor miehei lipase-catalyzed hidrolysis of 1,3-bis[3,5-bis(ethoxycarbonyl)-1H-pyrazol-1-yl]propane and the potential usefulness of the resulting acids as intermediates in the synthesis of podand and crown esters.

Research paper thumbnail of Regioselective Enzyme-catalyzed Synthesis of Pyrazole-containing Podands

HETEROCYCLES, 1993

Novel enzyme-mediated synthetic routes were developed to provide a new family of sophorolipid der... more Novel enzyme-mediated synthetic routes were developed to provide a new family of sophorolipid derivatives and glycolopid-based amphiphilic monomers. These compounds are of great interest for their potential use in immunoregulation, as well as for other biological properties. In the present work, an efficient lipase-catalyzed conversion of sophorolipid ethyl ester to (a) the 6′-monoacylated derivatives using Novozym 435, (b) 6′′-monoacylated derivatives using Lipase PS-C, (c) secondary amide derivatives using Novozym 435, and (d) 6′,6′′-diacylated amide derivatives using Novozym 435 in an one-pot reaction and (e) the regioselective monoacylation of an amide derivative at the 6′-and 6′′-positions using Novozym 435 and Lipase PS-C, respectively, are described. The ethyl ester produced by esterification of the sophorolipid mixture with sodium ethoxide was subjected to acylation catalyzed by Novozym 435 in dry tetrahedrofuran (THF) with vinyl acetate and vinyl methacrylate to produce 6′-monoacylated derivatives. In contrast, Lipase PS-C catalyzed acylations of sophorolipid ethyl ester in dry THF with vinyl acetate and vinyl methacrylate to give the corresponding 6′-monoacylated derivatives. Novozym 435 mediated amidation of sophorolipid ethyl ester in dry THF with phenethylamine, tyramine, p-methoxyphenethylamine, 2-(p-tolyl)ethylamine, and p-fluorophenethylamine generated the corresponding secondary amides but not tertiary amides. The formation of diacyl derivatives of amides was achieved by their treatment with vinyl acetate and vinyl methacrylate in dry THF using Novozym 435 as catalyst. The conversion of sophorolipid ethyl ester to the same diacyl derivatives of amide (i.e., both amidation and acylation) in high yield was also demonstrated in dry THF by a one-pot reaction using Novozym 435. Furthermore, regioselective monoacylation of a sophorolipid amide at 6′ and 6′′ in dry THF with vinyl acetate and vinyl methacrylate using Novozym 435 and Lipase PS-C was also demonstrated.

Research paper thumbnail of Regioselective lipase-catalyzed synthesis of l-glutamic α-monoamide derivatives. Effect of the N-blocking group

Tetrahedron, 1997

Several Block-L-Glu(OEt)-OEt (Block = amides, carbamates and trityl group) have been subjected to... more Several Block-L-Glu(OEt)-OEt (Block = amides, carbamates and trityl group) have been subjected to an aminolysis reaction catalyzed by the lipase B of Candida antarctica. The reaction took place in a regioselective manner and ot-monoamides were obtained in all cases (except the bulky trityl group that did not react). Besides the synthetic value of the method, the results may empirically point out to some features of the active site of the enzyme as the reaction rate was severely affected by volume and electronic characteristics of the blocking group. © 1997 Elsevier Science Ltd.

Research paper thumbnail of Resolution of 1-(4-amino-3-chloro-5-cyanophenyl)-2-bromo-1-ethanol by lipase mediated enantioselective alcoholysis, hydrolysis and acylation

Tetrahedron-asymmetry, 1998

Resolution of 1-(4-amino-3-chloro-5-cyanophenyl)-2-bromo-1-ethanol has been achieved by ethanol e... more Resolution of 1-(4-amino-3-chloro-5-cyanophenyl)-2-bromo-1-ethanol has been achieved by ethanol enantioselective lipase-catalysed alcoholysis, hydrolysis and acylation. Although a good enantioselectivity was observed in the three reactions, the best results were obtained by hydrolysis. This α-bromohydrin is an intermediate in the synthesis of a new adrenergic agent.

Research paper thumbnail of Selective carriers of norepinephrine and ammonium ions: Ionophoric properties and molecular modelling studies of diester crown compounds containing a 1,3-bis(1 H-pyrazol-1-yl)propane unit

Bioorganic & Medicinal Chemistry, 1997

Ionophoric properties of dipyrazolic crowns and podands containing a 1,3-bis(lH-pyrazol-1-yl)prop... more Ionophoric properties of dipyrazolic crowns and podands containing a 1,3-bis(lH-pyrazol-1-yl)propane unit in their structure are described. They show selectivity of ammonium vs alkali cations and interesting norepinephrine transport rates. A molecular modelling study has been used to elucidate the superstructures of the crown and ammonium cation complexes. 0 1997, Elsevier Science Ltd. All rights reserved.

Research paper thumbnail of Regioselective Mucor miehei lipase catalyzed synthesis of podands containing a 1,3-bis(1 H-Pyrazol-1-yl)propane unit

Tetrahedron, 1995

The synthesis of podands (acyclic crown ethers) including a 1,3-bis( 1H-pyrazol-1-yl)propane unit... more The synthesis of podands (acyclic crown ethers) including a 1,3-bis( 1H-pyrazol-1-yl)propane unit in their molecule is described. The key step of this synthesis was a regioselective lipase-catalyzed transesterification of the dipyrazolic tetraethylester 1 with monomethylether polyethyleneglycols. The ionophoric properties of the podands 4a-d as carriers of cations were evaluated. Molecular modelling studies and quantum-chemical calculations were used in order to elucidate the superestructtwes of the complexes with ammonium cations.

Research paper thumbnail of First regioselective mucor miehei lipase catalyzed synthesis of diester crowns. New macrocycles containing a 1,3-bis(1H-pyrazol-1-yl)propane unit

Bioorganic & Medicinal Chemistry Letters, 1994

... NEW MACROCYCLES CONTAINING A 1,3-BIS(1H-PYRAZOL-1-YL)PROPANE UNIT Marta Fierros, Maria Isabel... more ... NEW MACROCYCLES CONTAINING A 1,3-BIS(1H-PYRAZOL-1-YL)PROPANE UNIT Marta Fierros, Maria Isabel Rodriguez-Franco, Klar Navarro, and Santiago Conde* Instituto de Qufmica ... 2. Izatt, RM; Bradshaw, JS; Nielsen, SA; Lamb, JD; Christensen, JJ; Sen, S. Chem. Rev. ...

Research paper thumbnail of Regioselective lipase catalyzed synthesis of diester crowns. New asymmetric macrocycles containing a 1,3-bis(1 H-pyrazol-1-yl)propane unit

Tetrahedron, 1997

Several Block-L-Glu(OEt)-OEt (Block = amides, carbamates and trityl group) have been subjected to... more Several Block-L-Glu(OEt)-OEt (Block = amides, carbamates and trityl group) have been subjected to an aminolysis reaction catalyzed by the lipase B of Candida antarctica. The reaction took place in a regioselective manner and ot-monoamides were obtained in all cases (except the bulky trityl group that did not react). Besides the synthetic value of the method, the results may empirically point out to some features of the active site of the enzyme as the reaction rate was severely affected by volume and electronic characteristics of the blocking group. © 1997 Elsevier Science Ltd.

Research paper thumbnail of X-ray Crystallography at 170 K of Racemic 2,2'-Dimethoxy-9,9'-biacridine and 1H NMR Study of 2,2'Diacetoxy9,9'-biacridine

Molecules, 1999

Three derivatives of 9,9'-biacridine, 2,2'-dihydroxy, 2,2'-dimethoxy and 2,2'diacetoxy have been ... more Three derivatives of 9,9'-biacridine, 2,2'-dihydroxy, 2,2'-dimethoxy and 2,2'diacetoxy have been prepared. The crystal structure of racemic 2,2'-dimethoxy-9,9'-biacridine CHCl 3 1:1 complex has been determined and shows an almost perpendicular conformation of both acridine rings. 1 H NMR experiments using the diacetoxy derivative and both Eu(tfc) 3 and R-Pirkle's alcohol show the splitting of some signals characteristic of a racemic compound.