Aromatic compounds fluorinated amino acids

These compounds can be prepared by using either classical processes for synthesis of amino acids (starting from the ad hoc precursor bearing fluorine on the aromatic moiety) or electrophilic fluorination of the arene moiety (e.g., elemental fluorine, xenon fluoride, acetyl hypofluorite). Although these methods are often poorly regioselective, they are useful for the preparation of F labeled molecules used in PET, for example, F tyrosine and dihydrophenylalanine (L-Dopa). ... 

Another powerful approach to prepare a-amino acids bearing an aromatic or unsaturated side chain in /I (but also many other compounds) is based on the reactivity of 5-fluoro-4-trifluoromethyloxazole, a starting material easily accessible from hexafluoroacetone. The fluorine atom in the 5 position is easily displaced by an allylic or benzylic alcohol. Then, the obtained ethers spontaneously undergo a Claisen rearrangement to afford, after acidic hydrolysis, an a-trifluoromethyl amino acid... 

Synthesis of Phosphoric Acids and Their Derivatives. - A series of monoalkyl and dialkyl phosphorus acid chiral esters have been synthesised for use as carriers for the transport of aromatic amino acids through supported liquid membranes. The compounds acted as effective carriers but enantio-separation was at best moderate. A range of phosphono- and phosphoro-fluoridates have been prepared by treatment of the corresponding thio- or seleno- phosphorus acids with aqueous silver fluoride at room temperature (Scheme 1). In some cases oxidation rather than fluorination occurred. Stereospecifically deuterium-labelled allylic isoprenoid diphosphates, e.g. (1), have been synthesised from the corresponding deuterium-labelled aldehyde by asymmetric reduction, phosphorylation and Sn2 displacement with pyrophosphate (Scheme 2). ... 

Halogen bound to an aromatic ring is rendered considerably more reactive by nitro groups in the para- or, especially, the ortho-position to it carboxyl, sulfonyl, and cyano groups have considerably less effect. Among such activated halo aromatic compounds the relative reactivities of the halogens are reversed, and fluorine is much the most reactive. This is used for, e.g.9 determination of A-terminal amino acids in peptides by means of l-fluoro-2,4-dinitrobenzene.547 The ease of reaction is illustrated in the following example ... 

Contents Trifluoromethyl Aromatic Compounds (R. Filler) Aliphatic Fluoro-amino Acids (F. Loncrini and R. Filler) Fluoro-alcohols (S. K. De and S. R. Palit) Polyfluoroaromatic Derivatives of Metals and Metalloids (S. C. Cohen and A. G. Massey) The Chemistry of Organic Nitrogen Fluorides (J. P. Freeman) Fluorine Compounds of lenium and Tellurium (B. Cohen and R. D. Peacock) Madelung Constants as a New Guide in the Structural Chemistry of Solids (R. Hoppe). 

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