Hydrochloric Acid → ethyl 5-(3-butyl-8-chloro-2,6-dioxo-2,3,6,7-tetrahydro-1H-purin-1-yl)pentanoate

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Reaction Conditions

Reaction Steps

To 3-butyl-8-chloro-7-(2-propen-1-yl)-3,7-dihydro-1H-purine-2,6-dione (1.5 g, 5.31 mmol) in dry DMF (25 ml) was added Cs2CO3 (1.905 g, 5.84 mmol), followed by ethyl 5-bromovalerate (1.46 g, 6.99 mmol). The mixture was heated at 55° C. for 18 h then allowed to cool. It was degassed by repeatedly evacuating and readmitting nitrogen, then morpholine (3.70 ml, 42.5 mmol) and tetrakis(triphenylphosphine)palladium(0) (1.0 g, 0.865 mmol) were added and the mixture stirred for 5 h. EtOAc (75 ml), 2M HCl (40 ml) and water (20 ml) were added and the organic phase was separated, washed with brine (3×25 ml), filtered to remove some insoluble yellow solid, dried (Na2SO4) and evaporated. The residue (2.5 g) was purified by aminopropyl SPE (20 g), loading in THF-MeOH (1:1), washing with MeOH and eluting the product with DCM-MeOH (1:1) containing 5% added AcOH to afford the title compound (1.53 g).

Provenance & Evidence