Jon Parquette - Academia.edu (original) (raw)

Papers by Jon Parquette

Organic Letters, Nov 8, 2006

Synthesis of Dendron 1 and Associated Complexes. a 90% Scheme 1. Conditions: a) 1. NaN 3 , DMF 60... more Synthesis of Dendron 1 and Associated Complexes. a 90% Scheme 1. Conditions: a) 1. NaN 3 , DMF 60°C; 2. NaBH 4 , i-PrOH/THF; b) 4chloropyridine-2,6-dicarbonyl chloride, CH 2 Cl 2 , pyr.

Journal of the American Chemical Society, Jan 5, 2006

General. 1 H and 13 C-NMR spectra were collected on a Bruker DRX-400 or DRX-500 spectrometers. MS... more General. 1 H and 13 C-NMR spectra were collected on a Bruker DRX-400 or DRX-500 spectrometers. MS analysis was performed by electrospray or MALDI-TOF mass spectrometry as indicated by The Ohio State University Campus Chemical Instrumentation Center. All starting materials were from commercial suppliers and used as received unless otherwise noted. Tetrahydrofuran (THF) was distilled from sodium/benzophenone; CH 2 Cl 2 and pyridine was distilled from calcium hydride. All melting points are recorded in glass capillaries and are uncorrected. Thin-layer chromatography was performed on aluminum-backed Merck Silica gel 60 F254 plates. Separation by flash chromatography were performed with Merck silica gel 9385 (100 mesh). 2-Nitroacetanilide. 1 2-Nitroaniline 1 (41 g, 0.3 mol, 1.0 equiv) and acetic anhydride (32 mL, 33 g, 0.33 mol, 1.1 equiv) were mixed in 150 mL acetic acid and heated at reflux for 4 h. After cooling the mixture to rt, water (1 L) was added and the mixture was filtered. The filtrate was extracted with CHCl 3 (500 mL), providing 6.3 g of 2 as a yellow solid after drying over Na 2 SO 4 and concentrating. The precipitate was dissolved in CHCl 3 (500 mL), washed with water (500 mL), dried (Na 2 SO 4) and concentrated to yellow solid (47.7 g). The combined products weighed 53.7 g (yield 99 %) and was used without further purification.

ChemInform, Jul 3, 2014

Bimetallic Catalysis in the Highly Enantioselective Ring-Opening Reactions of Aziridines.-The app... more Bimetallic Catalysis in the Highly Enantioselective Ring-Opening Reactions of Aziridines.-The applied catalyst is readily prepared from commercially available yttrium isopropoxides. Mechanistic studies suggest that both the aziridine and the cyanide or azide are activated at two different metals of the bimetallic complex.-(WU,

Angewandte Chemie, Jan 26, 2009

Supramolecular Chemistry, Oct 1, 2003

The synthesis and cation binding properties of a folded ditopic crown receptor, 3, are described.... more The synthesis and cation binding properties of a folded ditopic crown receptor, 3, are described. Intramolecular hydrogen-bonding interactions preorganize ditopic crown 3 into a helical conformation that positions the crown moieties in a manner that favors the formation of an intramolecular sandwich cation complex. Alkali-metal picrate extraction studies demonstrate that ditopic crown 3 exhibits a significantly different cation selectivity than mono-crown congener 2. A crystal structure of 3•2KClO indicates that two molecules of the complex are assembled into a molecular square in the solid state.

Chemical Communications, 2005

Chloro-N,N′-bis[(S)-2-chloro-1-methylethyl]pyridine-2,6-dicarboxamide. A mixture of (S)-(+)-2-ami... more Chloro-N,N′-bis[(S)-2-chloro-1-methylethyl]pyridine-2,6-dicarboxamide. A mixture of (S)-(+)-2-amino-1-propanol (1.80 g, 1.90 ml, 24.40 mmol) and methyl 4-chloropyridine-2,6dicarboxylate (2.30 g, 10.00 mmol) was heated at 90 °C for 2 h. The mixture was diluted with CHCl 3 (50 ml) followed by the addition of SOCl 2 (7.14 g, 4.38 ml, 60.00 mmol). The reaction was heated at reflux for 1 h and concentrated under vacuum. The residue was chromatographed over silica using a 95:5 CH 2 Cl 2 :EtOAc mobile phase. Product was isolated as a white crystalline solid (3.06 g, 87 %); mp 165-167 °C (CH 2 Cl 2); 1 H NMR (CDCl 3) δ 1.43 (d,

Angewandte Chemie, Jan 26, 2009

Chemical Science, 2014

Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.

Tetrahedron, Aug 1, 2005

ABSTRACT The synthesis of linear and branched di-, tri- and tetramannosides on a commercially ava... more ABSTRACT The synthesis of linear and branched di-, tri- and tetramannosides on a commercially available hyperbranched polyester as a soluble, high loading support is described. Glycosylation products were isolated in 26–63% yield as mixtures of anomers after total hydrolytic degradation of the polymer. All polymer-bound intermediates were purified through simple extraction or precipitation. Solution-phase NMR and MALDI-TOF were used to monitor the progress of the reaction directly on the hyperbranched polymer support.

John Wiley & Sons, Inc. eBooks, Jul 11, 2008

Page 312. CHAPTER 11 STRUCTURE AND SELF-ASSEMBLY OF AMPHIPHILIC DENDRIMERS IN WATER HUI SHAO and ... more Page 312. CHAPTER 11 STRUCTURE AND SELF-ASSEMBLY OF AMPHIPHILIC DENDRIMERS IN WATER HUI SHAO and JON R. PARQUETTE 11.1. INTRODUCTION The spontaneous segregation of polar and apolar segments ...

Israel Journal of Chemistry, May 1, 2009

ABSTRACT Isomeric “compact” and “expanded” dendrimers functionalized with L-prolinamide catalytic... more ABSTRACT Isomeric “compact” and “expanded” dendrimers functionalized with L-prolinamide catalytic units at the periphery were compared as catalysts to monomer controls in the organocatalytic direct aldol condensation. A positive dendritic effect that amplifies the stereoselectivity of the direct aldol condensation was observed for dendrimers 3 and 4, compared with lower molecular weight catalysts L-prolinani-lide 1 and G1 dendron 2. The difference in the compactness between 3 and 4 appears to have less impact on the stereoselectivity than the preorganized multivalency of the dendritic catalysts.

Journal of Organic Chemistry, Oct 25, 2006

of energies, dipole moments, and natural population analyses of all stationary points located for... more of energies, dipole moments, and natural population analyses of all stationary points located for 2,6-OMe-IPA and 2,6-pydic S2-S24

Proceedings of The Royal Society A: Mathematical, Physical and Engineering Sciences, Aug 26, 2009

A series of pyridine-2,6-dicarboxamide dendrons having varying proportions of chiral and achiral ... more A series of pyridine-2,6-dicarboxamide dendrons having varying proportions of chiral and achiral termini have been prepared. Circular dichroism and X-ray crystallographic studies indicate that these folded dendrons propagate terminal chirality via a 'sergeants and soldiers' process. The extent of chiral amplification shows a dependence on dendron generation, but also is affected by the relative positioning of the chiral termini at the periphery of the dendron. Analysis of the crystal structures of the G1 dendrons, 4a-6a, reveals chain-chain and chain-dendron conformational communication, which is likely to be responsible for the chiral amplification observed in solution.

Biotechnology for Biofuels, Jul 6, 2017

Background: With increasing concerns over global warming and depletion of fossil-fuel reserves, i... more Background: With increasing concerns over global warming and depletion of fossil-fuel reserves, it is attractive to develop innovative strategies to assimilate CO 2 , a greenhouse gas, into usable organic carbon. Cell-free systems can be designed to operate as catalytic platforms with enzymes that offer exceptional selectivity and efficiency, without the need to support ancillary reactions of metabolic pathways operating in intact cells. Such systems are yet to be exploited for applications involving CO 2 utilization and subsequent conversion to valuable products, including biofuels. The Calvin-Benson-Bassham (CBB) cycle and the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) play a pivotal role in global CO 2 fixation. Results: We hereby demonstrate the co-assembly of two RubisCO-associated multienzyme cascades with selfassembled synthetic amphiphilic peptide nanostructures. The immobilized enzyme cascades sequentially convert either ribose-5-phosphate (R-5-P) or glucose, a simpler substrate, to ribulose 1,5-bisphosphate (RuBP), the acceptor for incoming CO 2 in the carboxylation reaction catalyzed by RubisCO. Protection from proteolytic degradation was observed in nanostructures associated with the small dimeric form of RubisCO and ancillary enzymes. Furthermore, nanostructures associated with a larger variant of RubisCO resulted in a significant enhancement of the enzyme's selectivity towards CO 2 , without adversely affecting the catalytic activity. Conclusions: The ability to assemble a cascade of enzymes for CO 2 capture using self-assembling nanostructure scaffolds with functional enhancements show promise for potentially engineering entire pathways (with RubisCO or other CO 2-fixing enzymes) to redirect carbon from industrial effluents into useful bioproducts.

Angewandte Chemie, Sep 6, 2010

Journal of the American Chemical Society, May 29, 2008

Chemistry: A European Journal, Oct 5, 2011

Journal of the American Chemical Society, May 1, 2004

Organic Letters, Nov 8, 2006

Synthesis of Dendron 1 and Associated Complexes. a 90% Scheme 1. Conditions: a) 1. NaN 3 , DMF 60... more Synthesis of Dendron 1 and Associated Complexes. a 90% Scheme 1. Conditions: a) 1. NaN 3 , DMF 60°C; 2. NaBH 4 , i-PrOH/THF; b) 4chloropyridine-2,6-dicarbonyl chloride, CH 2 Cl 2 , pyr.

Journal of the American Chemical Society, Jan 5, 2006

General. 1 H and 13 C-NMR spectra were collected on a Bruker DRX-400 or DRX-500 spectrometers. MS... more General. 1 H and 13 C-NMR spectra were collected on a Bruker DRX-400 or DRX-500 spectrometers. MS analysis was performed by electrospray or MALDI-TOF mass spectrometry as indicated by The Ohio State University Campus Chemical Instrumentation Center. All starting materials were from commercial suppliers and used as received unless otherwise noted. Tetrahydrofuran (THF) was distilled from sodium/benzophenone; CH 2 Cl 2 and pyridine was distilled from calcium hydride. All melting points are recorded in glass capillaries and are uncorrected. Thin-layer chromatography was performed on aluminum-backed Merck Silica gel 60 F254 plates. Separation by flash chromatography were performed with Merck silica gel 9385 (100 mesh). 2-Nitroacetanilide. 1 2-Nitroaniline 1 (41 g, 0.3 mol, 1.0 equiv) and acetic anhydride (32 mL, 33 g, 0.33 mol, 1.1 equiv) were mixed in 150 mL acetic acid and heated at reflux for 4 h. After cooling the mixture to rt, water (1 L) was added and the mixture was filtered. The filtrate was extracted with CHCl 3 (500 mL), providing 6.3 g of 2 as a yellow solid after drying over Na 2 SO 4 and concentrating. The precipitate was dissolved in CHCl 3 (500 mL), washed with water (500 mL), dried (Na 2 SO 4) and concentrated to yellow solid (47.7 g). The combined products weighed 53.7 g (yield 99 %) and was used without further purification.

ChemInform, Jul 3, 2014

Bimetallic Catalysis in the Highly Enantioselective Ring-Opening Reactions of Aziridines.-The app... more Bimetallic Catalysis in the Highly Enantioselective Ring-Opening Reactions of Aziridines.-The applied catalyst is readily prepared from commercially available yttrium isopropoxides. Mechanistic studies suggest that both the aziridine and the cyanide or azide are activated at two different metals of the bimetallic complex.-(WU,

Angewandte Chemie, Jan 26, 2009

Supramolecular Chemistry, Oct 1, 2003

The synthesis and cation binding properties of a folded ditopic crown receptor, 3, are described.... more The synthesis and cation binding properties of a folded ditopic crown receptor, 3, are described. Intramolecular hydrogen-bonding interactions preorganize ditopic crown 3 into a helical conformation that positions the crown moieties in a manner that favors the formation of an intramolecular sandwich cation complex. Alkali-metal picrate extraction studies demonstrate that ditopic crown 3 exhibits a significantly different cation selectivity than mono-crown congener 2. A crystal structure of 3•2KClO indicates that two molecules of the complex are assembled into a molecular square in the solid state.

Chemical Communications, 2005

Chloro-N,N′-bis[(S)-2-chloro-1-methylethyl]pyridine-2,6-dicarboxamide. A mixture of (S)-(+)-2-ami... more Chloro-N,N′-bis[(S)-2-chloro-1-methylethyl]pyridine-2,6-dicarboxamide. A mixture of (S)-(+)-2-amino-1-propanol (1.80 g, 1.90 ml, 24.40 mmol) and methyl 4-chloropyridine-2,6dicarboxylate (2.30 g, 10.00 mmol) was heated at 90 °C for 2 h. The mixture was diluted with CHCl 3 (50 ml) followed by the addition of SOCl 2 (7.14 g, 4.38 ml, 60.00 mmol). The reaction was heated at reflux for 1 h and concentrated under vacuum. The residue was chromatographed over silica using a 95:5 CH 2 Cl 2 :EtOAc mobile phase. Product was isolated as a white crystalline solid (3.06 g, 87 %); mp 165-167 °C (CH 2 Cl 2); 1 H NMR (CDCl 3) δ 1.43 (d,

Angewandte Chemie, Jan 26, 2009

Chemical Science, 2014

Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.

Tetrahedron, Aug 1, 2005

ABSTRACT The synthesis of linear and branched di-, tri- and tetramannosides on a commercially ava... more ABSTRACT The synthesis of linear and branched di-, tri- and tetramannosides on a commercially available hyperbranched polyester as a soluble, high loading support is described. Glycosylation products were isolated in 26–63% yield as mixtures of anomers after total hydrolytic degradation of the polymer. All polymer-bound intermediates were purified through simple extraction or precipitation. Solution-phase NMR and MALDI-TOF were used to monitor the progress of the reaction directly on the hyperbranched polymer support.

John Wiley & Sons, Inc. eBooks, Jul 11, 2008

Page 312. CHAPTER 11 STRUCTURE AND SELF-ASSEMBLY OF AMPHIPHILIC DENDRIMERS IN WATER HUI SHAO and ... more Page 312. CHAPTER 11 STRUCTURE AND SELF-ASSEMBLY OF AMPHIPHILIC DENDRIMERS IN WATER HUI SHAO and JON R. PARQUETTE 11.1. INTRODUCTION The spontaneous segregation of polar and apolar segments ...

Israel Journal of Chemistry, May 1, 2009

ABSTRACT Isomeric “compact” and “expanded” dendrimers functionalized with L-prolinamide catalytic... more ABSTRACT Isomeric “compact” and “expanded” dendrimers functionalized with L-prolinamide catalytic units at the periphery were compared as catalysts to monomer controls in the organocatalytic direct aldol condensation. A positive dendritic effect that amplifies the stereoselectivity of the direct aldol condensation was observed for dendrimers 3 and 4, compared with lower molecular weight catalysts L-prolinani-lide 1 and G1 dendron 2. The difference in the compactness between 3 and 4 appears to have less impact on the stereoselectivity than the preorganized multivalency of the dendritic catalysts.

Journal of Organic Chemistry, Oct 25, 2006

of energies, dipole moments, and natural population analyses of all stationary points located for... more of energies, dipole moments, and natural population analyses of all stationary points located for 2,6-OMe-IPA and 2,6-pydic S2-S24

Proceedings of The Royal Society A: Mathematical, Physical and Engineering Sciences, Aug 26, 2009

A series of pyridine-2,6-dicarboxamide dendrons having varying proportions of chiral and achiral ... more A series of pyridine-2,6-dicarboxamide dendrons having varying proportions of chiral and achiral termini have been prepared. Circular dichroism and X-ray crystallographic studies indicate that these folded dendrons propagate terminal chirality via a 'sergeants and soldiers' process. The extent of chiral amplification shows a dependence on dendron generation, but also is affected by the relative positioning of the chiral termini at the periphery of the dendron. Analysis of the crystal structures of the G1 dendrons, 4a-6a, reveals chain-chain and chain-dendron conformational communication, which is likely to be responsible for the chiral amplification observed in solution.

Biotechnology for Biofuels, Jul 6, 2017

Background: With increasing concerns over global warming and depletion of fossil-fuel reserves, i... more Background: With increasing concerns over global warming and depletion of fossil-fuel reserves, it is attractive to develop innovative strategies to assimilate CO 2 , a greenhouse gas, into usable organic carbon. Cell-free systems can be designed to operate as catalytic platforms with enzymes that offer exceptional selectivity and efficiency, without the need to support ancillary reactions of metabolic pathways operating in intact cells. Such systems are yet to be exploited for applications involving CO 2 utilization and subsequent conversion to valuable products, including biofuels. The Calvin-Benson-Bassham (CBB) cycle and the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) play a pivotal role in global CO 2 fixation. Results: We hereby demonstrate the co-assembly of two RubisCO-associated multienzyme cascades with selfassembled synthetic amphiphilic peptide nanostructures. The immobilized enzyme cascades sequentially convert either ribose-5-phosphate (R-5-P) or glucose, a simpler substrate, to ribulose 1,5-bisphosphate (RuBP), the acceptor for incoming CO 2 in the carboxylation reaction catalyzed by RubisCO. Protection from proteolytic degradation was observed in nanostructures associated with the small dimeric form of RubisCO and ancillary enzymes. Furthermore, nanostructures associated with a larger variant of RubisCO resulted in a significant enhancement of the enzyme's selectivity towards CO 2 , without adversely affecting the catalytic activity. Conclusions: The ability to assemble a cascade of enzymes for CO 2 capture using self-assembling nanostructure scaffolds with functional enhancements show promise for potentially engineering entire pathways (with RubisCO or other CO 2-fixing enzymes) to redirect carbon from industrial effluents into useful bioproducts.

Angewandte Chemie, Sep 6, 2010

Journal of the American Chemical Society, May 29, 2008

Chemistry: A European Journal, Oct 5, 2011

Journal of the American Chemical Society, May 1, 2004