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

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Reaction Steps

5-Benzyloxy-2-(2-bromobenzyl)-6-oxo-3,6-dihydro-pyrimidine-4-carboxylic acid (2-hydroxyethyl)-isopropylamide (70) (0.21 g, 420 μmol, Eq: 1.00) and Ph3P (143 mg, 546 μmol, Eq: 1.3) were stirred in dichloromethane (5 ml) at room temperature for ˜15 min. Then diisopropyl azodicarboxylate (116 mg, 112 μl, 546 μmol, Eq: 1.3) was added and the resulting mixture was stirred at room temperature overnight. The solvent was removed. The remaining material was purified by SiO2 flash chromatography (hexanes/ethyl acetate 5-50%, then dichloromethane/methanol 0-4% methanol). 300 mg of 9-benzyloxy-6-(2-bromobenzyl)-2-isopropyl-3,4-dihydro-2H-pyrazino[1,2-c]pyrimidine-1,8-dione (71) (˜40% pure, ˜60% yield) as light yellow solid were isolated and used as obtained.

Provenance & Evidence