Alanine 3.3.3- trifluoro

Enzymes modified with N -carbonyldiimidazole (CDI) include horseradish peroxidase 761 /1-lactamase after nitration and reduction,[771 lysozyme, and urease.[781 Ref. [77] describes how the tyrosine side chain of a protein was nitrated, reduced with dithionite to an amino group, and then treated with CDI or A/-(2,2,2-trifluoro-ethoxycarbonyl)imidazole to give the benzoxazolinonyl alanine moiety ... 

Mono-, di- and trifluoro-derivates of alanine Chiral ProCu 1-2.5 mM CUSO4 222... 

In fact, the first saturated pseudoxazolone reported, 4-methyl-2-(trifluoro-methyl)-5(2//)-oxazolone, was incorrectly assigned as the tautomeric 5(4//)-oxazolone and only later did nuclear magnetic resonance (NMR) smdies establish the correct structure. This compound was synthesized from alanine and trifluoro-acetic anhydride (TFFA). This methodology constitutes, under standard conditions, the most general procedure for the synthesis of 5(2//)-oxazolones. 

The Cotton effects in mixed amino acidate/acetylacetonate complexes [Cr(acac)2L] (L = l-alanine, L-valine or L-phenylalanine) have been studied 774 absolute configurations were assigned by reference to the parent tris(acetylacetonate) complexes. Synthesis was achieved by the photolysis of mixtures of the amino acid and [Cr(acac)3]. The partial photoresolution of both cis- and irans-(l,l,l-trifluoro-2,4-pentanedionato)chromium has been accomplished by irradiation with circularly polarized light (5461 A) in chlorobenzene solution.775 The results indicated that both bond rupture and twist mechanisms were important. A number of other jS-diketonates have also been investigated.776... 

The sequence with oxazole 73 also proves to be applicable to systems in which the double bond of the allylic alcohol fragment is incorporated into a heteroaromatic ring, such as in furfuryl alcohol (77a) and thiophene-2-methanol (77b).28 After hydrolysis of the oxazolone ring with water, V-benzoyl-3,3,3-trifluoro-2-(2-methyl-3-furyl)alanine (79a) and /V-benzoyl-3,3,3-trifluoro-2-(2-melhyl-3-thienyl)alanine (79b) are obtained. The 2-methylene helerocyclcs 78 originally formed in the Claisen rearrangement undergo rearomatizalion under the reaction conditions. 

N,N dimethylhydrazine reacts in the same fashion, while hydrazine gave only 9 % of the azine together with the reduction product 7. The reduction of imines 8 yields the corresponding trifluoro-alanine derivatives 2. The hindered imines 8 are very stable and do not undergo [4+2] cycloadditions or addition of butyl-lithium, and even LiAlH4 reacts very sluggishly. 

Alexeev et have examined the inhibition by trifluoro alanine, according to the well-known ability of fluoro amino acids to inactivate PLP-dependent enzymes. They indeed observe an irreversible inactivation and established the structure of the adduct. When the crystals of the protein were soaked in a buffer containing trifluoro alanine, they observed the adduct 10 (Figure 10), whereas when the incubation was carried out in solution, the amide 11, resulting from HF elimination, was obtained. The postulated mechanism implies a decarboxylation of the external aldimine in the first step. This is rather surprising since in the normal mechanism, decarboxylation occurs in the intermediate [I]. 

Fig. 4. Chromatogram of separation on a silicone stationary phase of methyl esters of trifluoro-acetylated amino acids of hydrolysate of human fingernail. Sorbent silicone stationary phase. Temperature programme A, 100°C, isothermal B, heating from 100°C at 1.5°C/min C, heating from 116.5°C at 4°C/min D, 140°C, isothermal E, heating from 140°C at 6°C/min to 210°C. Peaks 1 = alanine 2 = valine 3 = glycine 4 = isoleucine 5 = threonine 6 = leucine 7 = norleucine 8 = internal standard 9 = proline 10 = asparagine 11 = glutamine 12 = phenylalanine 13 = tyrosine 14 = lysine. From ref. 13.

The Diels-Alder reaction between fiuoranil and 1-acetoxybutadiene in benzene, which gives the adduct (121), occurs at room temperature when the solution is in contact with silica gel, and the reaction is believed to take place within the pores of the adsorbent the technique may be of general applicability.i Fiuoranil reacts with the ethyl ester of DL-a-alanine in ethanol to give the 2,5-disubstituted product (122), and a similar reaction apparently occurs with ethyl-glycine. The reaction of 2,3,4-trifluoro-l-nitroanthraquinone with amines (NHa, MeNHa, EtaNH, or piperidine) in benzene gives mixtures of 2- and 4-substituted products, but some 3-substitution also occurs when the solvent is dimethyl sulphoxide l,3,4-trifluoro-2-nitroanthraquinone reacts only at the 3-position with the same amines in either solvent. Treatment of the products of these reactions with zinc in acetic acid results in simple reduction of -NOa to -NHa. ... 

A second group of analytical methods requires preliminary acid hydrolysis. This is conducted in 7 M HCl at 95 to 9TC for 4 h (73) or in 1 M HCl at 80°C for 3 h (23). The hydrolysis product p-alanine has been analyzed after its conversion to the corresponding Ar-trifluoroacetyl methyl ester or jv-trifluoro-acetyl butyl ester. Derivatization of p-alanine is a two-step procedure. The compound is converted first to its methyl or butyl ester using alcoholic HCl and then to its AT-trifluoroacetate by the use of trifluoroacetic acid anhydride. The resulting derivative is analyzed using a polar stationary phase (23). 

Racemic dinitropyridyl, dinitrophenyl, and dinitrobenzoyl amino acids were resolved on C-18W/UV TLC and HPTLC plates (Macherey-Nagel) developed with 2% aqueous isopropanol containing 2-5% BSA. Development times were 1-2 h, and visualization was under 254 nm UV hght. Ri differences ranged from 0.06 to 0.49 [34]. The same plates with mobile phases composed of isopropanol -E BSA-E sodium tetraborate, acetic acid, or sodium carbonate served to separate enantiomeric D,L-methylthiohydantoin andphenylthiohydantoin derivatives of amino acids, kynureyne, 3-(l-naphthyl)alanine, lactic acid derivatives, alanine and leucine p-nitroanilides, and 2,2,2-trifluoro-l-(9-anthryl)ethanol [35], and with mobile phases composed of water with 5-7% BSA -E 2% isopropanol to separate dansyl amino acid derivatives [36]. 

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