Scheme 1
Reagents and Conditions: (
a
) Chloroacetyl chloride, NaOH, CH
2
Cl
2
/H
2
O, rt, 1 h; (
b
)
t-
BuOK, toluene, rt, 3 h; (
c
) NaH, ethyl bromoacetate, DMF, N
2
, 0°C, rt, 1.5 h; (
d
) KOH, MeOH, reflux, 2 h.