Aluminium lithium hydride → 2-Methyl-N2-phenyl-N1-(2,4,6-trimethylphenyl)-1,2-propanediamine

Participants

Reaction Steps

A solution of the amide (100 mg, 0.337 mmol) in dry dimethoxyethane (2 ml) was added lithium aluminum hydride (80 mg, 2.1 mmol), and the mixture was refluxed for 1 day. After cooling to room temperature, the reaction was quenched by adding H2O (0.08 ml), 15% aqueous NaOH (0.08 ml), and H2O (0.24 ml) successively. The white precipitation was filtered off and the filtrate was purified by column chromatography on silica (eluent: Hexane/Ethyl acetate=10/1) to give N1-mesityl-2-methyl-N2-phenylpropane-1,2-diamine as a pale yellow solid (54 mg, 0.192 mmol, Y=57%). The diamine (1.45 g, 5.14 mmol) was converted to the corresponding dihydrochloride salt (1.83 g, 5.14 mmol, 100%) by treating with HCl solution (4 M in dioxane). A mixture of this salt (500 mg, 1.4 mmol) and triethyl orthoformate (4.7 ml) was stirred at 130° C. for 5 min then cooled. After cooling to room temperature, the white precipitation was collected by filtration washing with large amount of diethyl ether and then with acetone to give the desired imidazolidinium chloride salt (367 mg, 1.12 mmol, Y=80%). 1H NMR (300 MHz, CDCl3): δ 9.76 (s, 1H), 7.65-7.62 (m, 2H), 7.49-7.47 (m, 3H), 6.92 (s, 2H), 4.13 (s, 2H), 2.39 (s, 6H), 2.27 (s, 3H), 1.69 (s, 6H). 13C NMR (75 MHz, CDCl3): δ 158.4, 140.2, 134.9, 132.3, 130.2, 130.0, 129.9, 129.8, 127.4, 68.6, 63.7, 26.7, 20.9, 18.1. IR: 3401 (m), 2975 (w), 1624 (s), 1592 (m), 1301 (w), 1263 (m), 1219 (m), 856 (w), 776 (w) cm−1. HRMS Calc'd for C20H25N2: 293.2018. Meas: 293.2021.

Provenance & Evidence