Scheme 1. Synthesis of triazolophostins. (a) H2SO4-silica, Ac2O, DCM, rt, 12 h, 90%; (b) TMSN3, AlCl3, DCM, 0 °C, 10 min, 99%; (c) NaOMe, MeOH, rt, 30 min, 96%; (d) (i) (iPr)2NP(OBn)2, ImOTf, DCM, rt, 1 h, (ii) m-CPBA, –78 °C, 45 min, 90%; (e) (i) trimethylsilylacetylene, Cu, CuSO4, H2O : tBuOH, rt, 12 h; (ii) TBAF, THF, rt, 2 h, (95% for two steps); (f) alkyne, Cu, CuSO4, H2O : tBuOH, rt, 12 h, 48–97%; (g) cyclohexene, Pd(OH)2, MeOH : H2O, 80 °C, 4 h, Bn = benzyl, Ac = acetyl, Me = methyl.
