The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Guiseppe Della Gatta - One of the best experts on this subject based on the ideXlab platform.
-
Heat capacities, and enthalpies and entropies of fusion of some uncharged small peptides (N-acetylamino acid amides and 2,5-diketopiperazines)
The Journal of Chemical Thermodynamics, 1997Co-Authors: Lorenzo Abate, Bartłomiej Pałecz, Concetta Giancola, Guiseppe Della GattaAbstract:Molar heatcapacities at constant pressure of solidN-acetylamides of glycine,l-alanine,l-valine,l-leucine,l-isoleucine, and cyclic anhydrides of glycine (2,5-Piperazinedione), glycine, andl-alanine (3-methyl-2,5-Piperazinedione),l-alanine (3,6-dimethyl-2,5-Piperazinedione), and sarcosine (1,4-dimethyl-2,5-Piperazinedione) were measured by differential scanning calorimetry. Calibration methods and experimental procedures adopted are described. Measurements were made from ambient temperature to below the melting temperatures, and values atT=298.15 K were derived by extrapolating the smoothed fitting equations. The molar heatcapacitiesCp,matT=298.15 K increase linearly as a function of molar mass, with an increment of (26±1) J · K−1 · mol−1for CH2group, for both series of linear and cyclic compounds. Temperatures, enthalpies, and entropies of fusion of both groups of compounds were also determined. They are discussed on the basis of crystal structures given in the literature
-
Heat Capacities and Fusion Enthalpies and Entropies of Some Uncharged Small Peptides (N-acetylamino Acid Amides and 2,5-Diketopiperazine)
'Elsevier BV', 1997Co-Authors: B. Palecz, Concetta Giancola, Guiseppe Della GattaAbstract:Molar heatcapacities at constant pressure of solidN-acetylamides of glycine,l-alanine,l-valine,l-leucine,l-isoleucine, and cyclic anhydrides of glycine (2,5-Piperazinedione), glycine, andl-alanine (3-methyl-2,5-Piperazinedione),l-alanine (3,6-dimethyl-2,5-Piperazinedione), and sarcosine (1,4-dimethyl-2,5-Piperazinedione) were measured by differential scanning calorimetry. Calibration methods and experimental procedures adopted are described. Measurements were made from ambient temperature to below the melting temperatures, and values atT=298.15 K were derived by extrapolating the smoothed fitting equations. The molar heatcapacitiesCp,matT=298.15 K increase linearly as a function of molar mass, with an increment of (26±1) J · K−1 · mol−1for CH2group, for both series of linear and cyclic compounds. Temperatures, enthalpies, and entropies of fusion of both groups of compounds were also determined. They are discussed on the basis of crystal structures given in the literature
Lin Wenhan - One of the best experts on this subject based on the ideXlab platform.
-
Janthinolide A-B, two new 2,5-Piperazinedione derivatives from the endophytic Penicillium janthinellum isolated from the soft coral Dendronephthya sp
die pharmazie, 2006Co-Authors: Xue Chunmei, Li Tian, Deng Zhiwei, Fu Hongzheng, Lin WenhanAbstract:Two new 2,5-Piperazinedione derivatives, janthinolide A and B (1-2), along with deoxymycelianamide, griseofulvin and dechlorogriseofulvin were isolated from the fermentation broths of the endophytic fungus Penicillium janthinellum isolated from a soft coral, Dendronephthya sp. Their structures were established by extensive spectroscopic data analysis.SCI(E)PubMed0ARTICLE121041-46
-
Janthinolide A-B, two new 2,5-Piperazinedione derivatives from the endophytic Penicillium janthinellum isolated from the soft coral Dendronephthya sp.
pharmazie, 2006Co-Authors: Xue Chunmei, Li Tian, Deng Zhiwei, Fu Hongzheng, Lin WenhanAbstract:Two new 2,5-Piperazinedione derivatives, janthinolicle A and B (1-2), along with deoxymycelianamide, griseofulvin and dechlorogriseofulvin were isolated from the fermentation broths of the endophytic fungus Penicillium janthinellum isolated from a soft coral, Dendronephthya sp. Their structures were established by extensive spectroscopic data analysis.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000242876600015&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Chemistry, MedicinalChemistry, MultidisciplinaryPharmacology & PharmacySCI(E)16121041-10446
Steven J. Geib - One of the best experts on this subject based on the ideXlab platform.
-
Fluorous Synthesis of Hydantoin-, Piperazinedione-, and Benzodiazepinedione-Fused Tricyclic and Tetracyclic Ring Systems
European journal of organic chemistry, 2006Co-Authors: Wei Zhang, Christine Hiu-tung Chen, Dennis P. Curran, Steven J. GeibAbstract:Fluorous proline derivatives generated from one-pot, three-component [3+2] cycloaddition of azomethine ylides are employed for different post-condensation reactions to form hydantoin-, Piperazinedione-, and benzodiazepinedione-fused tricyclic and tetracyclic ring systems. The high synthetic efficiency is achieved by conducting fast microwave reactions and easy fluorous-solid phase extractions for reaction mixture purifications. Methods developed for these novel drug-like heterocyclic compounds can be applied to diversity-oriented library synthesis.
Eugene A Mash - One of the best experts on this subject based on the ideXlab platform.
-
A synchrotron study of (2R,5'S)-5'-benzyl-5-bromo-6-methoxyspiro[indane-2,2'-piperazine]-3',6'-dione dimethylformamide solvate.
Acta crystallographica. Section C Crystal structure communications, 2010Co-Authors: Gary S Nichol, Francis N Murigi, Eugene A MashAbstract:Synchrotron radiation was used to study the structure of the title compound, C(20)H(19)BrN(2)O(3).C(3)H(7)NO, which was obtained as fine fragile needle-shaped crystals by recrystallization from dimethylformamide (DMF), one molecule of which is incorporated per asymmetric unit into the crystal. The compound adopts a compact closed conformation with the orientation of the benzyl group such that the aryl ring is positioned over the Piperazinedione ring, resulting in a C(spiro)...C(trans)-C-C(Ph) pseudo-torsion angle of -3.3 (3) degrees . The five-membered ring is present in an expected envelope conformation and the six-membered Piperazinedione ring adopts a less puckered boat-like conformation. Reciprocal amide-to-amide hydrogen bonding between adjacent Piperazinedione rings and C-H...O interactions involving DMF molecules propagate in the crystal as a thick ribbon in the a-axis direction.
-
NOTE: Synthesis and Characterization of a Poly(acrylamide) with Pendant 1,4-piperazine-2,5-dione Moieties via Post-polymerization Cyclization
Journal of Macromolecular Science Part A, 2008Co-Authors: Jeffrey R. Hammaker, Eugene A MashAbstract:A poly(acrylamide) was synthesized from N α -Boc-N ϵ -acrolyl-l-lysylglycine methyl ester via radical polymerization. This polymer typically had Mn ∼ 100,000 g/mol, Mw ∼ 300,000 g/mol, and a Tg of 93°C. Removal of Boc with TFA and cyclization with DABCO™ in DMSO at 65°C afforded a soluble Piperazinedione-containing polymer that had a Tg of 157°C and thermal stability up to 300°C. These results demonstrate a viable and efficient synthetic route to Piperazinedione-containing polyacrylamides of high molecular weight. Related polymers that incorporate substituted indane moieties could be useful high Tg materials for fabrication of LC and NLO devices.
-
(S,S)-4''-Cyano-7,7''-dimethoxy-3',6'-dioxodispiro[indane-2,2'-piperazine-5',2''-indane]-4-carboxamide methanol solvate: interrupting the amide-to-amide hydrogen-bonded tape.
Acta crystallographica. Section C Crystal structure communications, 2008Co-Authors: Bhumasamudram Jagadish, Michael D Carducci, Alice Dawson, Gary S Nichol, Eugene A MashAbstract:The title methanol solvate, C(24)H(22)N(4)O(5).CH(3)OH, forms an extended three-dimensional hydrogen-bonded structure, assisted by the presence of several good donor and acceptor sites. It shows none of the crystal packing features typically expected of Piperazinediones, such as amide-to-amide R(2)(2)(8) hydrogen bonding. In this structure the methanol solvent appears to play only a space-filling role; it is not involved in any hydrogen bonding and instead is disordered over several sites. This study reports, to the best of our knowledge, the first crystal structure of an indane-containing Piperazinedione compound which exhibits a three-dimensional hydrogen-bonded structure formed by classical (N-H...O and N-H...N) hydrogen-bonding interactions.
-
the crystal packing of a strongly dipolar Piperazinedione
Tetrahedron Letters, 2000Co-Authors: Bhumasamudram Jagadish, Lawrence J Williams, Michael D Carducci, Christian Bosshard, Eugene A MashAbstract:Abstract A strongly dipolar piperazine-2,5-dione was synthesized in enantiomerically pure form, crystallized from DMSO, and the supramolecular organization of the crystals determined by X-ray crystallography. In contrast with non-polar or weakly polar Piperazinediones of similar molecular topography, which form tapes by reciprocal intermolecular amide-to-amide hydrogen bonding, the strongly dipolar Piperazinedione participated in hydrogen bonding with occluded DMSO. The dipoles of the Piperazinedione molecules were aligned and were opposed by the dipoles of the DMSO molecules. The cocrystals exhibited second harmonic generation when subjected to pulsed irradiation.
-
Organic crystal engineering with piperazine-2,5-diones. 2. Crystal packing of weakly dipolar Piperazinediones derived from 2-amino-4-bromo-7-methoxyindan-2-carboxylic acid
Tetrahedron, 1999Co-Authors: Lawrence J Williams, Bhumasamudram Jagadish, Michael D Carducci, Michael G. Lansdown, Eugene A MashAbstract:Abstract Piperazine-2,5-diones with the potential to manifest three chemically distinct and linearly independent intermolecular interactions were synthesized from the enantiomers of 2-amino-4-bromo-7-methoxyindan-2-carboxylic acid. Samples of enantiomerically pure, racemic, and meso Piperazinediones were characterized in the solid state by X-ray crystallography. “Ladder-like” intermolecular amide-to-amide hydrogen bonding interactions were observed in each case, establishing tape structures parallel to one crystallographic axis. The observed tape morphologies and crystal packing closely resemble that previously observed for a topographically similar tetramethoxy-Piperazinedione. The results obtained demonstrate that the weak dipoles associated with the p-bromoanisole moiety play no role in determining order in the crystalline state.
Janet S. Plummer - One of the best experts on this subject based on the ideXlab platform.
-
The design of potent and selective inhibitors of thrombin utilizing a Piperazinedione template: part 1.
Bioorganic & medicinal chemistry letters, 1999Co-Authors: Wayne L. Cody, Cuiman Cai, Annette Marian Doherty, Jeremy J. Edmunds, Lakshmi S. Narasimhan, Janet S. Plummer, Stephen T. Rapundalo, J. Ronald Rubin, Chad Alan Van HuisAbstract:Utilizing X-ray crystallography and molecular modeling, highly potent and selective peptidomimetic thrombin inhibitors have been designed containing a rigid Piperazinedione template. The synthesis and biological activity of these compounds will be described.
-
The design of potent and selective inhibitors of thrombin utilizing a Piperazinedione template: part 2.
Bioorganic & medicinal chemistry letters, 1999Co-Authors: Wayne L. Cody, Cuiman Cai, Annette Marian Doherty, Jeremy J. Edmunds, Lakshmi S. Narasimhan, Corinne E. Augelli-szafran, Kent A. Berryman, J.r. Penvose-yi, Janet S. PlummerAbstract:Potent and selective thrombin inhibitors have been prepared with a Piperazinedione template and L-amino acids. Likewise, incorporation of D-amino acids led to potent inhibitors with a novel mode of binding. Herein, the structure activity relationships and structural aspects of these compounds will be described.