The intrinsic conformational preferences of indoline-2-carboxylic acid (Inc) and its R-methylated derivative
(RMeInc) have been investigated using quantum mechanical calculations. Specifically, the behavior of their
N-acetyl-N′-methylamide derivatives, Ac-L-Inc-NHMe and Ac-L-RMeInc-NHMe, has been explored at the
B3LYP/6-31+G(d,p) level. Such amino acids are analogues of proline and (R-methyl)proline, respectively,
bearing a benzene ring fused to the Cγ-Cδ bond of the five-membered pyrrolidin...