Iodoethane → [(4S,5R)-5-ethyl-1,4-dimethyl-4-(3-nitro-phenyl)-6-oxo-1,4,5,6-tetrahydro-pyrimidin-2-yl]-carbamic acid tert-butyl ester

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Reaction Steps

To a solution of [(S)-1,4-dimethyl-4-(3-nitro-phenyl)-6-oxo-1,4,5,6-tetrahydro-pyrimidin-2-yl]-carbamic acid tert-butyl ester (165 mg, intermediate E1) in THF (3.0 ml) was added at −78° C. a solution of LDA (3 eq., 2.8 ml) and stirring was continued for 1 h. The mixture was treated at −78° C. with a solution of iodoethane (67 μl) in THF (2.0 ml) and stirring was continued at the same temperature for 1.5 h and at −20° C. for 16 hours. The mixture was quenched with saturated aqueous NH4Cl, extracted with diethyl ether, the organic layer was dried and evaporated. The residue was chromatographed on silica using n-heptane/ethyl acetate (4:1) to give [(4S,5R)-5-ethyl-1,4-dimethyl-4-(3-nitro-phenyl)-6-oxo-1,4,5,6-tetrahydro-pyrimidin-2-yl]-carbamic acid tert-butyl ester (96 mg) as a colorless foam. MS (ESI): m/z=391.3 [ M+H]+. The hydrogenation of the nitro group to give the aniline (intermediate F) was carried out as described in Scheme 1.

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