Aus 3.3.3-Trifluor-alanin (1) werden verschiedene N-Acyl-Derivate und Ester dargestellt. Ungewöhnlich ist die Bildung eines kristallinen Dicyclohexylammonium-Salzes und die Veresterung zu 2 mit ätherischem Diazomethan. Mit Basen tritt leicht Eliminierung von HF ein. Die Synthese von Dipeptid-Derivaten, die 1 enthalten, wird beschrieben.
Aus 3.3.3-三氟丙氨酸(1)werden verschiedene N-酰基衍生物和酯。UngewöhnlichIST模具教化EINES kriSTallinen二环己-Salzes UND死VereSTerungつ2 MITätherischem重氮甲烷。MIT Basen tritt leicht Eliminierung von HF ein。Die Synthese von Dipeptid- Derivaten ,死于1个焓,wird beschrieben。
Fluorierte Aminosäuren, IV. Darstellung von
<i>C</i>
‐Perfluoralkyl‐glycinen und 3.3.3‐Trichlor‐alanin
Eine allgemeine Synthesevon C-Perfluoralkyl-glycinen 1 wird beschrieben, die über N-Acyl-aldimine 2, 3-Amino-3-perfluoralkyl-N-acyl-propene- (1) 8 und C- Perfluoralkyl-N-acyl-glycine 9 verläft. Analog läßt sich auch 3.3.3- Trichlor-alanin (13) herstellen.
EINE汇报合成冯Ç -Perfluoralkyl-glycinen 1 wird beschrieben,模具黚Ñ酰基-醛亚胺2,3-氨基-3- perfluoralkyl- Ñ酰基-propene-(1)8 UND Ç - Perfluoralkyl- ñ -酰基甘氨酸9个版本。模拟量约3.3.3-三氯丙氨酸(13)。
Design of Radical-Resistant Amino Acid Residues: A Combined Theoretical and Experimental Investigation
作者:Anna K. Croft、Christopher J. Easton、Leo Radom
DOI:10.1021/ja029674v
日期:2003.4.1
Ab initio calculations have been used to design radical-resistant amino acid residues. Optimized structures of free and protected amino acids and their corresponding alpha-carbon-centered radicals were determined with B3-LYP/6-31G(d). Single-point RMP2/6-31G(d) calculations on these structures were then used to obtain radical stabilization energies, to examine the effect of steric repulsion between the side chains and amide carbonyl groups on the stability of alpha-carbon-centered peptide radicals. Relative to glycine, the destabilization for alanine and valine residues was found to be approximately 9 and 18 kJ mol(-1), respectively, which correlates with the reactivity of analogous amino acid residues in peptides toward hydrogen atom abstraction in conventional free radical reactions. To design amino acid residues that would resist radical reactions, strategies by which the steric effects could be magnified were considered. This resulted in the identification of tert-leucine and 3,3,3-trifluoroalanine as suitable molecules. With these amino acid residues, the destabilization of the alpha-carbon-centered radicals relative to that of glycine is increased substantially to approximately 36 and 41 kJ mol(-1), respectively. The theoretical predictions have been supported by experimental observations: a tert-leucine derivative was shown to be very slow to react with N-bromosuccinimide, while the corresponding trifluoroalanine derivative was found to be inert.