92398-52-2Relevant academic research and scientific papers
Hydrogen-bonded tapes based on symmetrically substituted diketopiperazines: A robust structural motif for the engineering of molecular solids
Palacin, Serge,Chin, Donovan N.,Simanek, Eric E.,MacDonald, John C.,Whitesides, George M.,McBride, Mary T.,Palmore, G. Tayhas R.
, p. 11807 - 11816 (2007/10/03)
A series of eight symmetrically substituted diketopiperazines (DKPs) derived from 1-amino-1-carboxycycloalkanes (n = 3-7; 3,3,5,5-tetramethylcyclohexane; 4,4-dimethylcyclohexane; 2-indan) were synthesized and their crystal structures determined. In the solid state, all eight compounds form two pairs of hydrogen bonds with two adjacent molecules to form a one-dimensional structure that we refer to as 'tapes'. These molecules represent a range of volumes and shapes that contain a common molecular fragment (DKP ring). We examined this series of compounds with three objectives in mind: (i) to establish the ability of the hydrogen-bonded 'tape' motif to persist through these differences in volume and shape; (ii) to provide a series of structurally related compounds to use to test computational methods of predicting crystal structure from molecular structure; (iii) to search for qualitative correlations between molecular structure and crystal packing. All compounds form tapes and with one exception, all tapes pack with their long axes parallel. When viewed down their long axis, two types of tapes emerge: planar and nonplanar. The type of tape that forms reflects the conformation adapted by the DKP ring-planar or boat. Planar tapes form when the angle (α) between the two planes defined by the cis-amides in the DKP ring is 180°; nonplanar tapes form when α 180°. Five of the eight compounds studied form planar tapes, the remaining three compounds form nonplanar tapes. Despite the variability in volume and shape represented by this series of molecules, the persistence of the tape motif in their crystalline solids suggests that the hydrogen-bonding interactions between parallel alignment of tapes that pack in a manner that permits the interdigitation of substituents on adjacent tapes.
Peptide Sweeteners. 6. Structural Studies on the C-Terminal Amino Acid of L-Aspartyl Dipeptide Sweeteners
Tsang, Joseph W.,Schmied, Bernhard,Nyfeler, Rolf,Goodman, Murray
, p. 1663 - 1668 (2007/10/02)
Stereochemical and structural aspects of the variations in the C-terminal residue of L-aspartyl-L-phenylalanine methyl ester have been investigated.Novel configurational analogues such as L-aspartyl-D-alanine benzyl ester and L-aspartyl-D-α-aminobutyric acid benzyl ester were found to be sweet.In addition, chiral and achiral α,α-dialkylglycine and α-aminocycloalkanecarboxylic acids were incorporated into the dipeptides.The L-aspartic acid based dipeptide derivatives of α-aminoisobutyric acid methyl ester, α-aminocyclopropanecarboxylic acid methyl ester, α-aminocyclobutanecarboxylic acid methyl ester, and α-aminocyclopentanecarboxylic acid methyl ester are sweet.Dipeptides with α-aminocyclohexanecarboxylic acid methyl ester and α-aminocycloheptanecarboxylic acid methyl ester are bitter, whereas the analogues with α-aminocyclooctanecarboxylic acid methyl ester, α,α-diethylglycine methyl ester, and α-aminoisobutyric acid benzyl ester are tasteless.Aspects on chirality and effective volume of the C-terminal residue are discussed and correlated with taste.
