--- Kondratenko, Yu. A. et al Glass Physics and Chemistry, 42(6), 621-626; 2016
For the ester formation, see
--- Gruzdev, M. S. et al Russian Journal of General Chemistry, 83(4), 652-658; 2013
General/Typical Procedure: Tris[2-(4-propyloxybenzoyloxy)ethyl]amine (Ia, n = 3). A 4.25 g portion of propyloxybenzoic acid was dissolved in 75 ml of chloroform in a round-bottom 250 ml flask, and at permanent stirring 1.17 g of triethanolamine was added. The mixture was stirred for 10 min, then 3.47 g of 1,3-dicyclohexylcarbodiimide and a catalytic amount of dimethylaminopyridine was added. The mixture was stirred for 12 h. The reaction mixture was then filtered through a glass frit filter. The filtrate was washed with 5% acetic acid (2×25 ml), 5% sodium chloride solution (2×25 ml), distilled water (2×25 ml), and dried over sodium sulfate. The solvent was removed on a rotary evaporator, the residue was chromatographed on silica gel, eluent chloroform, followed by recrystallization from acetonitrile. Tris[2-(benzoyloxy)triethyl]amine (Id) was obtained similarly. Yield 77%. M = 461.52. IR spectrum, ν, cm-1: 3147, 3032 s (C-H, Ar), 2971, 2889 s [(CH2)nCH3], 1786.88 s(C=O), 1213.26 s, (CO-O as), 1173.41 s (O-C-C as), 1398 s (Ar, s). 1H NMR spectrum (CDCl3), δ, ppm: 3.40 t (6H, NCH2, JHH 14,04 Hz); 7.03 m (6H, NCH2CH2, JHH 11.56 Hz); 7.31 m (3H Ph4-H, JHH 7.32 Hz); 7.46 m, (6H, Ph1,5-H, JHH 6.71 Hz,); 8.08 d (6H, Ph2,6-H, JHH 6.71 Hz). 13C NMR spectrum (CDCl3), δC, ppm: 58.01 (NCH2); 62.23 (NCH2CH2); 129.04 (C2,6-Ph); 130.59 (C3,5-Ph); 131.67 (C-Ph); 162.37 (OCPh); 171.59 (PhCOO). Found, %: N 5.85, C 70.12; N 3.02. C27H27O6N. Calculated, %: N 5.90, C 70.27; N 3.03; mp, ° 38.18.
It depends on what you want to do with the product. This is a simple acid/base reaction. You could must mix them neat, but that would likely get quite hot and hard to stir. The easiest would be to mix them in an equimolar ratio in a solvent. They would both dissolve in water, as would the salt. But if you want to isolate the product, water may not be the easiest to remove. You could make a concentrated solution of each in hot water and mix them carefully and slowly to control the exothermic reaction. At the end of the addition cool the water, and the salt should precipitate out. An alcohol solvent should also work if you want to isolate the salt. A good literature search is fairly easy to do and I would recommend that before any lab experiments.
The Passerini reactions of indane-1,2,3-trione, tosylmethyl isocyanide, and benzoic acid derivatives proceed at room temperature giving sterically congested 2,2-disubstituted indane-1,3-dione derivatives in quantitative yield. The reactions are one-pot, and the products obtained did not require any purification.