Phenylalanine methyl ester isocyanate

Amino acid ester isocyanates are useful synthetic building blocks, precursors to peptides and azapeptides, 7 8 chiral derivatizing agents,9 13 and reagents for the preparation of chiral chromatographic media.11 12 (S)-2-lsocyanato-3-phenylpropanoate (phenylalanine methyl ester isocyanate) has been used as a... 

Typical procedure. m-(TrifIuoromethyl)phenylalanme methyl ester isocyanate [310] Diphosgene (5.0 mL, 0.042 mol) was added to a suspension of m-(trifluoromethyl) phenylalanine methyl ester hydrochloride (8.51 g, 0.03 mol) in dry dioxane (75 mL) under nitrogen. The reaction mixture was refluxed overnight under an efficient hood, with the use of a gas trap (300 mL of 20% aqueous NaOH). Subsequent removal of the solvent in vacuo, followed by vacuum distillation of the oily residue, yielded 6.9 g (85%) of the pure isocyanate. 

Silica gel HPTLC plates were used with the following chiral reagents and analytes 7 -(-)-l-(l-naphthyl)ethyl isocyanate for six / ,5-)8-blocking agents with benzene/ethyl ether/acetone (88 10 5) mobile phase and UV absorption and fluorescence detection (Rf differences 0.05-0.09) [48] (/ )-(- -)-1-phenylalanine hydrochloride for ketoprofen, suprofen, and indoprofen with benzene/methanol (93 7) and chloroform/ethyl acetate (15 1) mobile phases andUV (254 nm) detection (R differences were 0.04-0.10, with the i -isomer migrating more slowly for each compound) [49] and (5)-(- -)-naproxen chloride for the methyl esters of 10 amino acids with toluene/dichloromethane/tetrahydrofiiran (5 1 2) mobile phase and UV detection (Rf differences 0.04-0.10, with the i -isomer always having a lower value than the 5-isomer) [50]. 

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