Table 3.

Optimization of the synthesis of cyclopentadienes.^[a]

Entry	Deviation from above[a]	Yield [%][b]
1	none	52 (50)[c]
2	catalyst A instead of B	45
3	catalyst D instead of B	–[d]
4	catalyst F instead of B	17
5	DCE instead of EtOAc	25
6	90 °C	33
7	120 °C	40

[a] Reaction conditions: 2 a (0.1 m in EtOAc), 5 a (1.5 equiv), catalyst B (5 mol %), 100 °C, 12 h. [b] The yield was determined by GC–FID with diphenylmethane as an internal standard. [c] The yield of the isolated product is given in parentheses. [d] Not detected. FID=flame ionization detection.