Methyl iodide → [(4S,5R)-1,4,5-trimethyl-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 (110 mg, intermediate E1) in THF (3.0 ml) was added at −78° C. a solution of LDA (3 eq., 1.95 ml) and stirring was continued for 1 h. The mixture was treated at −78° C. with a solution of iodomethane (38 μl) in THF (2.0 ml) and stirring was continued at the same temperature for 1.5 h. 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 (5:1) to give [(4S,5R)-1,4,5-trimethyl-4-(3-nitro-phenyl)-6-oxo-1,4,5,6-tetrahydro-pyrimidin-2-yl]-carbamic acid tert-butyl ester (72 mg) as a colorless foam. MS (ESI): m/z=377.4 [ 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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