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Juan Jesus Lopez Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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conformational relaxation of s carvone and r limonene studied by microwave fourier transform spectroscopy and quantum chemical calculations
Structural Chemistry, 2013Co-Authors: Juan Ramon Aviles Moreno, T R Huet, Juan Jesus Lopez GonzalezAbstract:S-(+)-carvone (C10H14O, 5-Isopropenyl-2-methylcyclohex-2-en-1-one) and R-(+)-limonene (C10H16, 4-Isopropenyl-1-methylcyclohexene) have been characterized in the gas phase using a Fourier transform microwave spectrometer coupled to a supersonic molecular beam. Two conformers—with the Isopropenyl Group in the equatorial position—have been detected for each compound and described by a set of molecular parameters including the principal rotational constants and the quartic centrifugal distortion parameters. Quantum chemical calculations indicate that a third conformer might not be observed due to relaxation processes in the jet. The gas phase results are compared with the liquid phase IR-Raman-VCD spectra.
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Conformational relaxation of S-(+)-carvone and R-(+)-limonene studied by microwave Fourier transform spectroscopy and quantum chemical calculations
Structural Chemistry, 2013Co-Authors: Juan Ramon Aviles Moreno, T R Huet, Juan Jesus Lopez GonzalezAbstract:S-(+)-carvone (C_10H_14O, 5-Isopropenyl-2-methylcyclohex-2-en-1-one) and R-(+)-limonene (C_10H_16, 4-Isopropenyl-1-methylcyclohexene) have been characterized in the gas phase using a Fourier transform microwave spectrometer coupled to a supersonic molecular beam. Two conformers—with the Isopropenyl Group in the equatorial position—have been detected for each compound and described by a set of molecular parameters including the principal rotational constants and the quartic centrifugal distortion parameters. Quantum chemical calculations indicate that a third conformer might not be observed due to relaxation processes in the jet. The gas phase results are compared with the liquid phase IR-Raman-VCD spectra.
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conformational preference of a chiral terpene vibrational circular dichroism vcd infrared and raman study of s limonene oxide
Physical Chemistry Chemical Physics, 2009Co-Authors: Juan Ramon Aviles Moreno, Francisco Partal Ureña, Juan Jesus Lopez GonzalezAbstract:S-(−)-Limonene oxide (4-Isopropenyl-1-methyl-7-oxabicyclo[4.1.0]heptane) is a secondary metabolite and an atmospheric pollutant product of oxidation of other terpenes, such as limonene and α-pinene, among others. For the first time, a theoretical study of the molecular structure and a theoretical and experimental analysis of the infrared and Raman spectra of this chemical species are presented. Theoretical calculations reveal the existence of two conformers depending on the position of the Isopropenyl Group (axial and equatorial) and twelve rotamers (six equatorials and six axials), with the six equatorial ones as the most stable (around 97%) on the basis of Boltzmann’s distribution law. In the current work, from a reliable assignment of the IR and Raman spectra and with the help from the study of the VCD spectrum of the title compound, five rotamers have been detected experimentally in the liquid phase. The present work reveals that IR, Raman and VCD are helpful complementary techniques to characterize flexible systems, as terpenes, which present several conformers.
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Terpenes in the gas phase: The structural conformation of S-(–)-perillaldehyde investigated by microwave spectroscopy and quantum chemical calculations
Chemical Physics Letters, 2009Co-Authors: Juan Ramon Aviles Moreno, Juan Jesus Lopez Gonzalez, Francisco Partal Ureña, T R HuetAbstract:Abstract S -(–)-perillaldehyde (C 10 H 14 O) has been characterized in the gas phase using a Fourier transform microwave spectroscopy experiment in a supersonic molecular beam. Two conformers − with the Isopropenyl Group in the equatorial position − have been detected and described by a set of molecular parameters including the principal rotational constants and the quartic centrifugal distortion parameters. Quantum chemical calculations indicate that a third conformer might not be observed due to relaxation processes in the jet. The gas phase results are compared with the liquid phase IR–Raman–VCD spectra. Our study shows that gas phase spectroscopy is a powerful tool for characterizing monoterpenes.
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Conformational landscape in chiral terpenes from vibrational spectroscopy and quantum chemical calculations: S-(+)-carvone
Vibrational Spectroscopy, 2009Co-Authors: Juan Ramon Aviles Moreno, Francisco Partal Ureña, Juan Jesus Lopez GonzalezAbstract:S-(+)-carvone (5-Isopropenyl-2-methylcyclohex-2-en-1-one) is the primary component in the oil of caraway. Different experimental and theoretical works reveal that there are two possible conformers in which the Isopropenyl Group can be in equatorial or axial position. For each one, three rotamers were found theoretically, with the equatorial rotamers around 95% of the whole statistical population. In the current work, from a complete assignment of the IR and Raman spectra and the results obtained from the study of the VCD spectrum of the title compound, the three most stable rotamers have been detected experimentally in the liquid phase for the first time. The present work reveals that IR, Raman and VCD are helpful complementary techniques to characterize flexible systems, as terpenes, which present several conformers.
Artem Melman - One of the best experts on this subject based on the ideXlab platform.
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stereospecific intramolecular michael addition to carvone based on temporary sulfur connection
Tetrahedron Letters, 1998Co-Authors: Mario D. Bachi, Yaroslav V Bilokin, Artem MelmanAbstract:An acetic acid residue (CH2CO2Me) was stereoselectively attached to (−)-carvone (7) to give (1R,2S,5R)-(5-Isopropenyl-2-methyl-3-oxocyclohexyl)acetic acid methyl ester (21) in a process involving the following stages: i) addition of ClSCH2CO2Me to the Isopropenyl Group of 7 to give, after oxidation, [1-chloro-2(RS)-(1(R),4-methyl-5-oxocyclohex-3-enyl)propane-2-sulfonyl]acetic acid methyl ester (18); ii) intramolecular Michael addition of 18 to afford (1S,2S,4(RS),5R,8S)-4-chloromethyl-4,8-dimethyl-3,3,7-trioxo-3-thiabicyclo [3.3.1]nonane-2-carboxylic acid methyl ester (20); iii) disconnection of the acetic acid moiety by a tandem reductive elimination involving sulfur extrusion and restoration of the Isopropenyl Group (20 → 21).
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Enantioselective total synthesis of (-)-a-kainic acid
1998Co-Authors: Mario D. Bachi, Artem MelmanAbstract:a-Kainic acid and (-)-a-kainic acid ( 1) were synthesized. (-)-a-Kainic acid was obtained in 12% overall yield starting from tert-butyl isocyanoacetate. In the first step a chiral non-racemic oxazoline 19 was prepared. Oxazoline 19 was converted in three steps into the thioformimide 22 derived from a highly functionalized a-amino carboxylic acid. It was subjected to n-Bu3SnHlAIBN mediated free radical cyclization to enantiomerically pure pyrrolidine 25 which contain all the structural elements of (-)-a- kainic acid, except for the C-2 acetic acid moiety. This appendage was introduced by a new method of temporary sulfur connection. Accordingly, the 4-Isopropenyl Group was used as an anchor to which CH2C02Me was temporarily linked (26+13+ 14+15). It was then intramolecularly connected through a carbon-carbon bond to the pyrrolidine ring (15+ la), and eventually disconnected from its anchor by a sequential reductive double
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Stereospecific intramolecular Michael addition to (−)-carvone based on temporary sulfur connection
Tetrahedron Letters, 1998Co-Authors: Mario D. Bachi, Yaroslav V Bilokin, Artem MelmanAbstract:An acetic acid residue (CH2CO2Me) was stereoselectively attached to (−)-carvone (7) to give (1R,2S,5R)-(5-Isopropenyl-2-methyl-3-oxocyclohexyl)acetic acid methyl ester (21) in a process involving the following stages: i) addition of ClSCH2CO2Me to the Isopropenyl Group of 7 to give, after oxidation, [1-chloro-2(RS)-(1(R),4-methyl-5-oxocyclohex-3-enyl)propane-2-sulfonyl]acetic acid methyl ester (18); ii) intramolecular Michael addition of 18 to afford (1S,2S,4(RS),5R,8S)-4-chloromethyl-4,8-dimethyl-3,3,7-trioxo-3-thiabicyclo [3.3.1]nonane-2-carboxylic acid methyl ester (20); iii) disconnection of the acetic acid moiety by a tandem reductive elimination involving sulfur extrusion and restoration of the Isopropenyl Group (20 → 21).
Francisco Partal Ureña - One of the best experts on this subject based on the ideXlab platform.
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conformational preference of a chiral terpene vibrational circular dichroism vcd infrared and raman study of s limonene oxide
Physical Chemistry Chemical Physics, 2009Co-Authors: Juan Ramon Aviles Moreno, Francisco Partal Ureña, Juan Jesus Lopez GonzalezAbstract:S-(−)-Limonene oxide (4-Isopropenyl-1-methyl-7-oxabicyclo[4.1.0]heptane) is a secondary metabolite and an atmospheric pollutant product of oxidation of other terpenes, such as limonene and α-pinene, among others. For the first time, a theoretical study of the molecular structure and a theoretical and experimental analysis of the infrared and Raman spectra of this chemical species are presented. Theoretical calculations reveal the existence of two conformers depending on the position of the Isopropenyl Group (axial and equatorial) and twelve rotamers (six equatorials and six axials), with the six equatorial ones as the most stable (around 97%) on the basis of Boltzmann’s distribution law. In the current work, from a reliable assignment of the IR and Raman spectra and with the help from the study of the VCD spectrum of the title compound, five rotamers have been detected experimentally in the liquid phase. The present work reveals that IR, Raman and VCD are helpful complementary techniques to characterize flexible systems, as terpenes, which present several conformers.
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Terpenes in the gas phase: The structural conformation of S-(–)-perillaldehyde investigated by microwave spectroscopy and quantum chemical calculations
Chemical Physics Letters, 2009Co-Authors: Juan Ramon Aviles Moreno, Juan Jesus Lopez Gonzalez, Francisco Partal Ureña, T R HuetAbstract:Abstract S -(–)-perillaldehyde (C 10 H 14 O) has been characterized in the gas phase using a Fourier transform microwave spectroscopy experiment in a supersonic molecular beam. Two conformers − with the Isopropenyl Group in the equatorial position − have been detected and described by a set of molecular parameters including the principal rotational constants and the quartic centrifugal distortion parameters. Quantum chemical calculations indicate that a third conformer might not be observed due to relaxation processes in the jet. The gas phase results are compared with the liquid phase IR–Raman–VCD spectra. Our study shows that gas phase spectroscopy is a powerful tool for characterizing monoterpenes.
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Conformational landscape in chiral terpenes from vibrational spectroscopy and quantum chemical calculations: S-(+)-carvone
Vibrational Spectroscopy, 2009Co-Authors: Juan Ramon Aviles Moreno, Francisco Partal Ureña, Juan Jesus Lopez GonzalezAbstract:S-(+)-carvone (5-Isopropenyl-2-methylcyclohex-2-en-1-one) is the primary component in the oil of caraway. Different experimental and theoretical works reveal that there are two possible conformers in which the Isopropenyl Group can be in equatorial or axial position. For each one, three rotamers were found theoretically, with the equatorial rotamers around 95% of the whole statistical population. In the current work, from a complete assignment of the IR and Raman spectra and the results obtained from the study of the VCD spectrum of the title compound, the three most stable rotamers have been detected experimentally in the liquid phase for the first time. The present work reveals that IR, Raman and VCD are helpful complementary techniques to characterize flexible systems, as terpenes, which present several conformers.
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conformational flexibility in terpenes vibrational circular dichroism vcd infrared and raman study of s perillaldehyde
Journal of Physical Chemistry A, 2008Co-Authors: Francisco Partal Ureña, Juan Ramon Aviles Moreno, Juan Jesus Lopez GonzalezAbstract:S-(−)-Perillaldehyde (4-Isopropenylcyclohex-1-ene-1-carbaldehyde) is a secondary metabolite and an atmospheric pollutant obtained from the oxidation of other terpenes, as limonene and α-pinene, among others. For the first time, a study of the molecular structure and the infrared and Raman spectra of this chemical is presented. Theoretical calculations reveal the existence of two conformers depending on the position of the Isopropenyl Group (axial and equatorial) and twelve rotamers (six equatorials and six axials), being three of these equatorial rotamers the most stable (ca. 93%). A complete and reliable assignment of the IR and Raman spectra of the title compound is made, taking into account these three last rotamers, and the results are used to carry out a detailed interpretation, for the first time to our knowledge, of the VCD spectrum of this compound in the 1500−900 cm−1 region.
Juan Ramon Aviles Moreno - One of the best experts on this subject based on the ideXlab platform.
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conformational relaxation of s carvone and r limonene studied by microwave fourier transform spectroscopy and quantum chemical calculations
Structural Chemistry, 2013Co-Authors: Juan Ramon Aviles Moreno, T R Huet, Juan Jesus Lopez GonzalezAbstract:S-(+)-carvone (C10H14O, 5-Isopropenyl-2-methylcyclohex-2-en-1-one) and R-(+)-limonene (C10H16, 4-Isopropenyl-1-methylcyclohexene) have been characterized in the gas phase using a Fourier transform microwave spectrometer coupled to a supersonic molecular beam. Two conformers—with the Isopropenyl Group in the equatorial position—have been detected for each compound and described by a set of molecular parameters including the principal rotational constants and the quartic centrifugal distortion parameters. Quantum chemical calculations indicate that a third conformer might not be observed due to relaxation processes in the jet. The gas phase results are compared with the liquid phase IR-Raman-VCD spectra.
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Conformational relaxation of S-(+)-carvone and R-(+)-limonene studied by microwave Fourier transform spectroscopy and quantum chemical calculations
Structural Chemistry, 2013Co-Authors: Juan Ramon Aviles Moreno, T R Huet, Juan Jesus Lopez GonzalezAbstract:S-(+)-carvone (C_10H_14O, 5-Isopropenyl-2-methylcyclohex-2-en-1-one) and R-(+)-limonene (C_10H_16, 4-Isopropenyl-1-methylcyclohexene) have been characterized in the gas phase using a Fourier transform microwave spectrometer coupled to a supersonic molecular beam. Two conformers—with the Isopropenyl Group in the equatorial position—have been detected for each compound and described by a set of molecular parameters including the principal rotational constants and the quartic centrifugal distortion parameters. Quantum chemical calculations indicate that a third conformer might not be observed due to relaxation processes in the jet. The gas phase results are compared with the liquid phase IR-Raman-VCD spectra.
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conformational preference of a chiral terpene vibrational circular dichroism vcd infrared and raman study of s limonene oxide
Physical Chemistry Chemical Physics, 2009Co-Authors: Juan Ramon Aviles Moreno, Francisco Partal Ureña, Juan Jesus Lopez GonzalezAbstract:S-(−)-Limonene oxide (4-Isopropenyl-1-methyl-7-oxabicyclo[4.1.0]heptane) is a secondary metabolite and an atmospheric pollutant product of oxidation of other terpenes, such as limonene and α-pinene, among others. For the first time, a theoretical study of the molecular structure and a theoretical and experimental analysis of the infrared and Raman spectra of this chemical species are presented. Theoretical calculations reveal the existence of two conformers depending on the position of the Isopropenyl Group (axial and equatorial) and twelve rotamers (six equatorials and six axials), with the six equatorial ones as the most stable (around 97%) on the basis of Boltzmann’s distribution law. In the current work, from a reliable assignment of the IR and Raman spectra and with the help from the study of the VCD spectrum of the title compound, five rotamers have been detected experimentally in the liquid phase. The present work reveals that IR, Raman and VCD are helpful complementary techniques to characterize flexible systems, as terpenes, which present several conformers.
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Terpenes in the gas phase: The structural conformation of S-(–)-perillaldehyde investigated by microwave spectroscopy and quantum chemical calculations
Chemical Physics Letters, 2009Co-Authors: Juan Ramon Aviles Moreno, Juan Jesus Lopez Gonzalez, Francisco Partal Ureña, T R HuetAbstract:Abstract S -(–)-perillaldehyde (C 10 H 14 O) has been characterized in the gas phase using a Fourier transform microwave spectroscopy experiment in a supersonic molecular beam. Two conformers − with the Isopropenyl Group in the equatorial position − have been detected and described by a set of molecular parameters including the principal rotational constants and the quartic centrifugal distortion parameters. Quantum chemical calculations indicate that a third conformer might not be observed due to relaxation processes in the jet. The gas phase results are compared with the liquid phase IR–Raman–VCD spectra. Our study shows that gas phase spectroscopy is a powerful tool for characterizing monoterpenes.
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Conformational landscape in chiral terpenes from vibrational spectroscopy and quantum chemical calculations: S-(+)-carvone
Vibrational Spectroscopy, 2009Co-Authors: Juan Ramon Aviles Moreno, Francisco Partal Ureña, Juan Jesus Lopez GonzalezAbstract:S-(+)-carvone (5-Isopropenyl-2-methylcyclohex-2-en-1-one) is the primary component in the oil of caraway. Different experimental and theoretical works reveal that there are two possible conformers in which the Isopropenyl Group can be in equatorial or axial position. For each one, three rotamers were found theoretically, with the equatorial rotamers around 95% of the whole statistical population. In the current work, from a complete assignment of the IR and Raman spectra and the results obtained from the study of the VCD spectrum of the title compound, the three most stable rotamers have been detected experimentally in the liquid phase for the first time. The present work reveals that IR, Raman and VCD are helpful complementary techniques to characterize flexible systems, as terpenes, which present several conformers.
Mario D. Bachi - One of the best experts on this subject based on the ideXlab platform.
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stereospecific intramolecular michael addition to carvone based on temporary sulfur connection
Tetrahedron Letters, 1998Co-Authors: Mario D. Bachi, Yaroslav V Bilokin, Artem MelmanAbstract:An acetic acid residue (CH2CO2Me) was stereoselectively attached to (−)-carvone (7) to give (1R,2S,5R)-(5-Isopropenyl-2-methyl-3-oxocyclohexyl)acetic acid methyl ester (21) in a process involving the following stages: i) addition of ClSCH2CO2Me to the Isopropenyl Group of 7 to give, after oxidation, [1-chloro-2(RS)-(1(R),4-methyl-5-oxocyclohex-3-enyl)propane-2-sulfonyl]acetic acid methyl ester (18); ii) intramolecular Michael addition of 18 to afford (1S,2S,4(RS),5R,8S)-4-chloromethyl-4,8-dimethyl-3,3,7-trioxo-3-thiabicyclo [3.3.1]nonane-2-carboxylic acid methyl ester (20); iii) disconnection of the acetic acid moiety by a tandem reductive elimination involving sulfur extrusion and restoration of the Isopropenyl Group (20 → 21).
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Enantioselective total synthesis of (-)-a-kainic acid
1998Co-Authors: Mario D. Bachi, Artem MelmanAbstract:a-Kainic acid and (-)-a-kainic acid ( 1) were synthesized. (-)-a-Kainic acid was obtained in 12% overall yield starting from tert-butyl isocyanoacetate. In the first step a chiral non-racemic oxazoline 19 was prepared. Oxazoline 19 was converted in three steps into the thioformimide 22 derived from a highly functionalized a-amino carboxylic acid. It was subjected to n-Bu3SnHlAIBN mediated free radical cyclization to enantiomerically pure pyrrolidine 25 which contain all the structural elements of (-)-a- kainic acid, except for the C-2 acetic acid moiety. This appendage was introduced by a new method of temporary sulfur connection. Accordingly, the 4-Isopropenyl Group was used as an anchor to which CH2C02Me was temporarily linked (26+13+ 14+15). It was then intramolecularly connected through a carbon-carbon bond to the pyrrolidine ring (15+ la), and eventually disconnected from its anchor by a sequential reductive double
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Stereospecific intramolecular Michael addition to (−)-carvone based on temporary sulfur connection
Tetrahedron Letters, 1998Co-Authors: Mario D. Bachi, Yaroslav V Bilokin, Artem MelmanAbstract:An acetic acid residue (CH2CO2Me) was stereoselectively attached to (−)-carvone (7) to give (1R,2S,5R)-(5-Isopropenyl-2-methyl-3-oxocyclohexyl)acetic acid methyl ester (21) in a process involving the following stages: i) addition of ClSCH2CO2Me to the Isopropenyl Group of 7 to give, after oxidation, [1-chloro-2(RS)-(1(R),4-methyl-5-oxocyclohex-3-enyl)propane-2-sulfonyl]acetic acid methyl ester (18); ii) intramolecular Michael addition of 18 to afford (1S,2S,4(RS),5R,8S)-4-chloromethyl-4,8-dimethyl-3,3,7-trioxo-3-thiabicyclo [3.3.1]nonane-2-carboxylic acid methyl ester (20); iii) disconnection of the acetic acid moiety by a tandem reductive elimination involving sulfur extrusion and restoration of the Isopropenyl Group (20 → 21).
