tert-Butyl piperazine-1-carboxylate → 4-[4-Methyl-3-oxo-2-(2-trimethylsilanyl-ethoxymethyl)-2,3,4,10-tetrahydro-9-oxa-1,2,4a-triaza-phenanthren-6-yl]-piperazine-1-carboxylic acid tert-butyl ester

Participants

Reaction Steps

To a mixture of 6-bromo-4-methyl-2-(2-trimethylsilanyl-ethoxymethyl)-2,10-dihydro-9-oxa-1,2,4a-triaza-phenanthren-3-one (Preparation #1, Step E, 0.5 g, 1.173 mmol), tert-butyl piperazine-1-carboxylate (0.655 g, 3.52 mmol) and sodium 2-methylpropan-2-olate (0.225 g, 2.345 mmol) in toluene (50 mL) was added dicyclohexyl(2′,4′,6′-triisopropyl-[1,1′-biphenyl]-2-yl)phosphine (0.224 g, 0.469 mmol) and diacetoxypalladium (0.026 g, 0.117 mmol) and the reaction mixture was heated at reflux overnight. The reaction mixture was cooled to ambient temperature and concentrated in vacuo. The residue was purified by column chromatography on silica gel (eluting with 3-20% EtOAc in petroleum ether) to give 4-[4-methyl-3-oxo-2-(2-trimethylsilanyl-ethoxymethyl)-2,3,4,10-tetrahydro-9-oxa-1,2,4a-triaza-phenanthren-6-yl]-piperazine-1-carboxylic acid tert-butyl ester (0.210 g, 33%). 1H NMR (400 MHz, CDCl3) δ 6.92 (d, J=8.8 Hz, 1H), 6.56 (dd, J=2.6, 8.7 Hz, 1H), 6.50 (d, J=2.5 Hz, 1H), 5.18-5.05 (m, 2H), 4.73 (q, J=6.6 Hz, 1H), 4.65-4.52 (m, 2H), 3.67 (t, J=8.4 Hz, 2H), 3.63-3.57 (m, 4H), 3.04 (d, J=4.0 Hz, 4H), 1.58 (s, 5H), 1.51-1.46 (m, 12H), 1.03-0.94 (m, 2H), 0.02 (s, 9H).

Provenance & Evidence