C_5H_7Br + NaOEt rarr C_5H_6 +NaBrdarr +EtOH
C_5H_6 + NaOEt rarr [C_5H_5]^(-)Na^(+) +EtOH
"1 equiv" gives the diene, C_5H_6; the 2nd equiv gives cyclopentadienyl anion. These days, in inorganic laboratories, you can prepare 100*g quantities of base-free NaCp simply by boiling up sodium metal with dicyclopentadiene, C_10H_12,