(a) Anhydrous THF, Triphosgene (warning, triphosgene is toxic, see
Methods), reflux. (b) EtOH, Weinreb’s HCl salt,
reflux. (c) Anhydrous THF, n-Butyllithium, −78
°C. (d) Ethylacetoacetate, DMF, 4Å molecular sieves, 180
°C, µW. (e) 4:3 EtOH:H2O (0.05 M), 0 °C to r.t. (f)
hydrazine monohydrate, EtOH, 110 °C, µW. (g) Anhydrous THF,
4Å molecular sieves, 165 °C, µW.