Scheme 1. Synthetic routes to the first round of functionalisation. Reagents and conditions: (a) DIAD (1.1 equiv.), PPh3 (1.2 equiv.), 4 Å M.S. in THF, 77%. (b) NMO (1.2 equiv.), K2OsO4·2H2O (0.8 mol%) in THF/H2O 27% over two steps. (c) NaIO4 in H2O (1.4 equiv.), silica in DCM. (d) RNH2 (1.2 equiv.), STAB (3.0 equiv.), AcOH (0.1 equiv.), M.S. 4 Å in THF. (e) NaBH4 (1.1 equiv.) in MeOH. (f) NaH (60% dispersion in mineral oil) in dry THF, 0 °C, 1 h and then 2-chloropyrimidine, r.t., overnight, 67%.
