The carboxylic acids and secondary amines were obtained from Sigma-Aldrich or Acros. Dichloromethane were distilled over P 2 O 5 . Nuclear magnetic resonance spectroscopy was performed on a Brucker Avance 500. The In a 50.0 mL round-bottomed flask equipped with a magnetic stirrer, argon-inlet, and a reflux condenser TaCl 5 (238 mg, 0.666 mmol) was added followed by addition of a soln in CH 2 Cl 2 (4.0 mL), of the hexanoic acid (232 mg, 2.0 mmol). After a few min of vigorous stirring, a suspension formed and dibutylamine, (258 mg, 5.26 mmol) was introduced into the reaction mixture. In 0.5 h, the temperature was slowly raised to 45 °C and the reaction time was maintained 5 h or 6h at 45 o C. The reaction mixture was diluted with Et 2 O (5 mL), and 25 wt% KOH solution (3 mL) was added dropwise while the reaction flask was cooled in an ice bath. The aqueous layer was extracted with diethyl ether (3×10 mL). The combined organic layers were washed with brine (20 mL), dried over anhydrous MgSO 4 . The residue was distilled through a micro column at 20 mmHg to give 2a (248 mg, 77%) as a colourless oil. b.p. 77 -79 о С (20 mmHg). Evaporation of solvent and purification of the residue by column chromatography (hexane/ethyl acetate, 5:1) gave a yellow oil; yield: 350 mg, (77%); R f = 0.69 (hexane/ethyl acetate, 5:1).