Dimethyl Sulfate → 1-Benzyl 4-tert-butyl 2-methyl piperazine-1,2,4-tricarboxylate

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Reaction Steps

This step was carried out using the procedure described in Tetrahedron Letters 30 (39), 1989, 5193-5196. A 0.5 M solution of A1 in acetone was treated with K2CO3 (1.3 eq.) and Me2SO4 (1.2 eq.) and the mixture was refluxed 6 h. The reaction mixture was filtered and filtrate was concentrated under reduced pressure. The residue was dissolved in Et2O and washed with sat. aq. NaHCO3 solution, and brine, then dried and evaporated. The residue was purified by column chromatography on silica gel, eluting with 20-100% EtOAc/petroleum ether to give the title compound in 90% yield. 1H NMR (300 MHz, CDCl3, 300K) δ 7.35 (5H, m), 5.17 (2H, m), 4.77-4.50 (2H, m), 4.10-3.85 (1H, m), 3.74 (1.5H, s), 3.64 (1.5H, s), 3.30 (1H, m), 3.10 (1H, dd, J 13.6, 4.4), 2.86 (1H, m), 1.45 (9H, s). MS (ES+) C19H26N2O6 requires 378, found: 401 (M+Na)+.

Provenance & Evidence