Some New NSAIDs Prodrugs: An Efficient Synthesis, Spectral Characterization and X-ray Crystal Structure Studies

An efficient synthesis of some new NSAIDs prodrugs viz., (S)-ethyl 2-[(S)-2-(4-isobutylphenyl)propanamido]-4-methylpentanoate (1), (S)-ethyl 2-[(R)-2-(4-isobutylphenyl) propanamido]-4-methylpentanoate (2), (S)-dimethyl 2-[2-(2,3-dimethylphenylamino)benzamido]succinate (3) and (RS)-methyl-2-(2-(2,6-dichloro-3-methylphenylamino)benzamido) butanoate (4) with high purity were carried out by the amidation of RS-ibuprofen, mefenamic acid and meclofenamic acid with methyl ester and ethyl ester of amino acids L-leucine, Laspartic acid and DL-2-aminobutyric acid. The products formed were confirmed by IR, H-1 NMR, C-13 NMR, HR MS (1-4) and single crystal X-ray crystallography analysis (2-4). Compound (2) crystallizes in orthorhombic space group P212121 with unit cell dimensions a = 5.1931 (2) angstrom, b = 10.0031 angstrom, c = 41.0764 (11) angstrom, alpha = beta = gamma = 90 degrees, V = 2133.80 (12) angstrom(3), Z = 4. Compound (3) crystallizes in hexagonal space group P6s with unit cell dimensions a = 11.4965 (3) angstrom, b = 11.4965 (3) angstrom, c = 26.5323 (12) angstrom, alpha = beta = 90 degrees, gamma = 120 degrees, V = 3036.94 (18) angstrom(3), Z = 6. Compound (4) crystallizes in triclinic space group Pi with unit cell dimensions a = 8.7969 (3) angstrom, b = 10.6307 (3) angstrom, c = 11.8469 (4) angstrom, alpha = 76.724 (3)degrees, beta = 89.066 (3)degrees, gamma = 66.169 (2)degrees, V = 982.70 (5) angstrom(3), Z = 2.