Cl[C:2]1[C:7]([C:8]([O:10][CH2:11][CH3:12])=[O:9])=[CH:6][N:5]=[C:4]([S:13][CH3:14])[N:3]=1.[NH2:15][C@@H:16]1[CH2:21][CH2:20][CH2:19][C@H:18]([OH:22])[CH2:17]1.CCN(C(C)C)C(C)C>C(O)C>[OH:22][C@H:18]1[CH2:19][CH2:20][CH2:21][C@@H:16]([NH:15][C:2]2[C:7]([C:8]([O:10][CH2:11][CH3:12])=[O:9])=[CH:6][N:5]=[C:4]([S:13][CH3:14])[N:3]=2)[CH2:17]1Ethyl 4-chloro-2-(methylthio)pyrimidine-5-carboxylate (4.38 g, 18.82 mmol) and (1S,3R)-3-aminocyclohexanol (2.276 g, 19.76 mmol; prepared as described in Tetrahedron: Asymmetry 15:2051-2056 (2004)) were dissolved in ethanol (75 mL) before adding DIEA (4.93 ml, 28.2 mmol) and heating to 60° C. After 2 hrs, LCMS showed the desired product mass was the dominant peak formed. The reaction was removed from heat and concentrated. The crude material was purified on a 340G SNAP Biotage column (20-100% ethyl acetate in hexane) to give ethyl 4-((1R,3S)-3-hydroxy-cyclohexylamino)-2-(methylthio)pyrimidine-5-carboxylate (5 g, 16.06 mmol, 85% yield) as a white foam; MS (ESI) m/z 312.1 [M+1]+
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