Triphenylphosphine → 9-benzyloxy-6-(2,6-dichlorobenzyl)-2-isopropyl-3,4-dihydro-2H-pyrazino[1,2-c]pyrimidine-1,8-dione

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Reaction Steps

5-Benzyloxy-2-(2,6-dichlorobenzyl)-6-oxo-3,6-dihydro-pyrimidine-4-carboxylic acid (2-hydroxyethyl)-isopropylamide (64) (0.11 g, 224 μmol, Eq: 1.00) was dissolved in dichloromethane (1.5 ml) and Ph3P (88.3 mg, 336 μmol, Eq: 1.5) was added. The clear colorless solution was stirred at room temperature for approx. 10 min and then diisopropyl azodicarboxylate (diisopropylazodicarboxylate) (71.6 mg, 68.9 μl, 336 μmol, Eq: 1.5) was added. Stirring was continued at room temperature for 1 h. The solvent was removed and the remaining oil was purified by SiO2 flash chromatography (12 g SiO2, dichloromethane/methanol 0-3% methanol). SiO2 flash chromatography was repeated (12 g SiO2, hexanes/ethyl acetate 7-50% ethyl acetate, then dichloromethane/methanol 0-3% methanol) to afford 9-benzyloxy-6-(2,6-dichlorobenzyl)-2-isopropyl-3,4-dihydro-2H-pyrazino[1,2-c]pyrimidine-1,8-dione (65) (0.045 g, 95.3 μmol, 42.5% yield) as a white solid.

Provenance & Evidence