New Dipeptides Containing Thiazolidine-4-carboxylic Acid Derivatives: Synthesis and Characterization Using NMR Techniques and X-Ray Data.
作者:Nadia PELLEGRINI、Bernard REFOUVELET、Gregorio CRINI、Olivier BLACQUE、Marek M. KUBICKI、Jean-Francois ROBERT
DOI:10.1248/cpb.47.950
日期:——
New dipeptides, structural analogues of known immunomodulating agents, were prepared by stereospecific condensation between 2-substituted thiazolidine-4-carboxylate esters with N-substituted L-proline or L-thiaproline. The structure of these compounds has been elucidated by combination of NMR methods and X-ray analysis. In addition, NMR measurements on dipeptides indicated the presence of S-cis and S-trans conformers around the amide bonds.
Cysteine compounds represented by the following formula
wherein each symbol is as defined in the specification, and salts thereof, are superior in stability, have less odor, exhibit an eumelanin production suppressive effect, and are useful as cosmetic agents.
Both bulk crystals and nanocrystals of two helical complexes, [Cu(mu(2)center dot L)(H2O)](n) (1) and [Cu(mu(2)-L)(H2O)]center dot 2H(2)O}(n) (2) (H2L = thiazolidine-2,4-dicarboxylic acid), have been synthesized with the chiralities of right-handedness (1) and left-handedness (2), respectively. 4-Cyanopyridine and poly(vinylpyrrolidone) (PVP) have been applied to control the synthesis of complexes with different helicities in bulk-crystal and nanocrystal forms, respectively. 2 can be irreversibly transformed to 1 under heating. Associated with the conformation changing, the symmetry alters between nonpolar and polar space groups.
Chiral Ni(II) Coordination Polymers: Structure-Driven Effects of Temperature and Polyvinylpyrrolidone
Chiral Ni(II) coordination compounds with structures of [NiL(H2O)(3)] (1) and [NiL(H2O)]center dot 0.5H(2)O}(n) (2) (H2L = thiazolidine 2,4-dicaboxlic acid) have been successfully synthesized by the reaction of Ni(CH3COO)(2)center dot 4H(2)O and H2L in aqueous solution at 25 and 80 degrees C, respectively. From the same procedure with polyvinylpyrrolidone (PVP) as a surfactant, another corresponding micrometer-scale Ni(II) coordination polymer, [NiL(H2O)(2)]center dot H2O}(n) (3), has been obtained at both 25 and 80 degrees C, which shows a different structure (one-dimensional, ID) than both 1 (discrete molecule) and 2 (3D). The conversions of structures and conformations are directed by temperature and surfactant (PVP), as confirmed by powder and single-crystal X-ray diffraction. Circular Dichroism (CD) and Second Harmonic Generation (SHG) measurements of the products have been investigated as well; which indicate the potential applications of these products in chiral and nonlinear optical (NLO) areas.