67151-54-6Relevant academic research and scientific papers
CHIROPTICAL PROPERTIES AND CONFORMATION OF N-ACETYL-L-AMINO ACIDS N'-METHYLAMIDES WITH ALIPHATIC SIDE CHAINS
Malon, Petr,Pancoska, Petr,Budesinsky, Milos,Hlavacek, Jan,Pospisek, Jan,Blaha, Karel
, p. 2844 - 2861 (2007/10/02)
CD and 1H NMR spectra of L-alanine (I), L-leucine (II), L-valine (III)and L-terc-leucine (IV) N-acetyl N'-methylamides were measured at various experimental conditions involving changes of temperature, concentration and solvent polarity.The least flexible tert-leucine derivative IV exists predominantly either in right handed α-helical (αR) conformation (fluorinated alcohols, ethanol) or in extended (C5) conformation (cyclohexane, acetonitrile).In this compound the Φ angle is constrained to about -120 deg, excepting aqueous solution.The flexible amides I and II exhibit more complex conformational equilibria involving probably the 310, αR and C5 conformations.The 310 helical conformation is favoured in water, acetonitrile and non-fluorinated alcohols, while a higher participation of αR conformation is observed in strongly polar fluorinated alcohols.Conformational distribution of the valine derivative III is similar to IV in fluorinated alcohols and to amides I and II in other solvents.The Ceq7 conformation is clearly detected only in cyclohexane solutions of non-associated forms of I and II.
