Understanding the conformational behaviour of Ac-Ala-NHMe in different media. A joint NMR and DFT study.

The authors thank EaStCHEM, CNPq and FAPESP for the studentship (to R.A.C. #2011/01170-1, FAPESP), as is CNPq for the fellowship (R.R.).The conformational behaviour of Ac-Ala-NHMe was studied for the compound in the gas-phase and in solution by theoretical calculations and experimental 1H NMR. The conformational preferences of this compound showed to be resultant 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 used in order to simulate the effect of polar protic solvents in disrupting intramolecular hydrogen bonds involving the -NHMe group in Ac-Ala-NHMe.PostprintPeer reviewe