Reagents and conditions: (a) isopropyl chloroformate, EtOH, 0°C, 20 min; (b) Na2CO3, H2O, 15°C to 25°C, 1 h; (c) 3-chloropropionyl chloride, toluene, 100°C, 3 h; (d) diethyl amine, toluene, 100°C, 10 h; (e): 2-chloroacetyl chloride, toluene, 100°C, 3 h; (f) R1H, DMF, NaH, 25°C, 3 h; (g) NaI, acetone, 25°C, 12 h; (h) R1H, NaHMDS, N2, THF, 0°C to 25°C, 1.5 h.
#Purified or unpurified intermediate, with partial structural characterization (1H NMR, MS, or both).
*An intermediate chemical prepared, purified or unpurified, and used as raw starting material for the next step without structural characterization.