The use of Zirconium(IV) catalysts for the direct amidation of carboxylic acids and amines was also reported . J Org Chem 72:4798–4802, Di Gioia ML, Leggio A, Liguori A, Perri F, Siciliano C, Viscomi MC (2010) Preparation of N-Fmoc-N-methyl-α-amino acids and N-nosyl-N-methyl-α-amino acids. Part of Here, we report the successful TiCl4-mediated synthesis of secondary and tertiary amides starting from various carboxylic acid and amine precursors. Solid (95%); mp = 66–69 °C; Rf = 0.68; 1H NMR (300 MHz, CDCl3) δ: 7.42–7.17 (m, 5H), 5.65 (sbroad, 1H), 3.55 (s, 2H), 3.22–3.07 (m, 2H), 1.58–1.31 (m, 2H), 0.82 (t, J = 7.4 Hz, 3H); 13C-NMR (75 MHz, CDCl3) δ: 171.0, 135.1, 129.4, 129.0, 127.3, 43.8, 41.3, 22.7, 11.2; GC/MS (EI) m/z (% rel. J Org Chem 79:943–954, Dunetz JR, Magano J, Weisenburger GA (2016) Large-scale applications of amide coupling reagents for the synthesis of pharmaceuticals. Oil (85%); Rf = 0.73; 1H NMR (300 MHz, CDCl3) δ: 7.36–7.15 (m, 5H), 3.69 (s, 2H), 3.38 (q, J = 7.1 Hz, 2H), 3.28 (q, J = 7.1 Hz, 2H), 1.16–1.02 (m, 6H); 13C-NMR (75 MHz, CDCl3) δ: 170.2, 135.5, 128.7, 128.6, 126.6, 42.4, 40.9, 40.1, 14.2, 12.9; GC/MS (EI) m/z (% rel. The amidation reaction was performed in pyridine at 85 °C with a wide range of substrates providing the corresponding amide products in moderate to excellent yields and high purity. Prof. Steven Farmer (Sonoma State University). Missed the LibreFest? Leggio, A., Bagalà, J., Belsito, E.L. et al. ): 222 [M+∙] (17), 221 (42), 205 (7), 175 (4), 150 (100), 120 (13), 104 (25), 92 (8), 76 (14). They react more or less readily with primary and most secondary amines to form, respectively, ureas, thioureas (RNHCSNHR), amides, and salts of carbamic acid (RNHCO 2 − RNH 3 +). By using N-Boc-l-alanine and its enantiomer N-Boc-d-alanine as chiral carboxylic acids, and aniline as amine component, highly enantiomerically enriched anilides were synthesized, demonstrating that the developed procedure does not generate any significant loss of the optical integrity of the precursors. The direct conversion of a carboxylic acid to an amide is difficult because amines are very basic and tend to convert carboxylic acids to their highly unreactive carboxylate ions. Optimization of amidation reaction conditions was performed by choosing benzoic acid as model substrate. Methyl esters are often prepared by the reaction of carboxylic acids with diazomethane. Zh Org Khim 24:1968–1972, CAS Cookies policy. The oven temperature program was initially set at 70 °C with a hold of 2 min and ramped to 280 °C at 20 °C/min with a hold of 10 min. Solid (88%), mp = 88–90 °C; Rf = 0.81; 1H NMR (300 MHz, CDCl3) δ: 7.53 (d, J = 8.3 Hz, 2H), 7.40 (s, 1H), 7.36–7.22 (m, 2H), 7.11 (m, 1H), 2.42–2.29 (m, 2H), 1.80–1.60 (m, 2H), 1.41–1.13 (m, 24H,), 0.89 (t, J = 6.7 Hz, 3H); 13C-NMR (75 MHz, CDCl3) δ: 171.7, 137.9, 129.0, 124.2, 119.8, 37.8, 31.9, 29.7, 29.6, 29.5, 29.4, 29.3, 25.7, 22.7, 14.2; GC/MS (EI) m/z (% rel. Tetrahedron Lett 58:1512–1514, Di Gioia ML, Leggio A, Le Pera A, Liguori A, Siciliano C (2004) Highly stereoselective conversion of aryl peptidyl ketones into the corresponding peptide alcohols. ): 264 [M+∙] (17), 208 (24), 191 (28), 144 (18), 120 (28), 93 (100), (77 (25), 57 (92). Acta Chem Scand B 42:28–34, Shteinberg LY, Kondratov SA, Shein SM (1988) Metal-complex catalysis in acylation of aniline by substituted benzoic acids. The process takes place with nearly complete preservation of the stereochemical integrity of chiral substrates. Later carboxyamides from benzoic acids and different amines were obtained by using stochiometric amounts of various Lewis acid catalysts in refluxing toluene . The direct formation of amides by condensing non-activated carboxylic acids and amines is extremely attractive because of its low environmental impact. All authors read and approved the final manuscript. Protein Pept Lett 12:357–362, Leggio A, Belsito EL, Di Gioia ML, Leotta V, Romio E, Siciliano C, Liguori A (2015) Reduction of amide carbonyl group and formation of modified amino acids and dipeptides. : DE2110060; Pub. 1a, c) with the mixture and the integration gave the data for the enantiomeric excess (ee) calculation, which was 95% for the d-isomer and 93% for the L-isomer. RSC Adv 6:34468–34475, El-Faham A, Albericio F (2011) Peptide coupling reagents, more than a letter soup.
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