Table 2. Study on the Substituent Effect in the Reaction of Compounds 1 Carried out with 6 equiv of t-BuOK.

entrya	1–3	R1	R2	R3	R4	R5	2:3 ratiob	yield (%)
1	a	Me	C(O)Me	H	Cl	Cl	0.09:1.00	84c (2a+3a)
2	b	Me	C(O)Me	Me	Cl	Cl	1.00:0.88d	54c (2b+3b)
3	c	Et	C(O)Me	H	Cl	Cl	0.13:1.00	90c (2c+3c)
4	d	Bn	C(O)Me	H	Cl	Cl	0.25:1.00	62c (2d+3d)
5	f	Me	C(O)Pr	H	Cl	Cl	0.18:1.00	86c (2f+3f)
6	i	Me	Me	H	Cl	Cl	1:0	85c (2i)
7	l	Me	C(O)Me	H	OMe	Cl	1:0	74e (2l)
8	n	Me	C(O)Me	H	H	OMe	1:0	35e (2n)
9	o	Me	C(O)Me	H	H	H	1:0	59e (2o)

^aReagents and reaction conditions: substrate (0.6 mmol), t-BuOK (3.6 mmol), THF (3 mL), 30 min, then quenching with H₂O.

^bThe product ratio of the isolated mixtures was determined by ¹H NMR.

^cThe reaction was carried out at 25 °C.

^ddr = 1.00:0.16.

^eThe reaction was carried out at reflux temperature.