Cormanich Rodrigo A, Bühl Michael, Rittner Roberto
Chemistry Institute, University of Campinas, Campinas, SP 13083-970, Brazil.
Org Biomol Chem. 2015 Sep 21;13(35):9206-13. doi: 10.1039/c5ob01296a. Epub 2015 Jul 29.
The conformational behaviour of Ac-Ala-NHMe was studied in the gas-phase and in solution by theoretical calculations (B3LYP-D3/aug-cc-pVDZ level) and experimental (1)H NMR. The conformational preferences of this compound were shown to result from a complex interplay between the strengths of possible intramolecular hydrogen bonds, steric interactions, hyperconjugation, entropy effects and the overall dipole moments. The Ac-Ala-N(Me)2 derivative was studied in addition, to design a system akin to Ac-Ala-NHMe, but with disrupted intramolecular hydrogen bonds involving the -NHMe group, mimicking the effect of polar protic solvents.
通过理论计算（B3LYP-D3/aug-cc-pVDZ水平）和实验1H NMR，研究了Ac-Ala-NHMe在气相和溶液中的构象行为。该化合物的构象偏好是由可能的分子内氢键强度、空间相互作用、超共轭、熵效应和整体偶极矩之间的复杂相互作用导致的。此外，还研究了Ac-Ala-N(Me)2衍生物，以设计一个类似于Ac-Ala-NHMe的体系，但涉及-NHMe基团的分子内氢键被破坏，模拟了极性质子溶剂的效果。
