Table 1. Optimization Studies of Cascade Reaction.

entrya	cat.	base	time (h)	drb	yieldc (%)	eed (%)
1	C1	K2CO3	24	17/1	58	99
2	C2	K2CO3	24	3/1	39	92
3	C3	K2CO3	24	3/1	58	91
4	C1	Na2CO3	48	20/1	55	99
5	C1	NaHCO3	168	20/1	32	99
6	C1	DIPEA	24	2/1	49	98
7e	C1	K2CO3	2	3/1	38	91
8f	C1	K2CO3	3	8/1	23	99
9g	C1	K2CO3	24	>20/1	59	99
10h	C1	K2CO3	18	>20/1	57	99
11i	C1	K2CO3	45	>20/1	64	99

^aReactions were conducted with 1a (0.1 mmol), 2a (0.2 mmol), corresponding base (0.2 mmol), and catalyst (20 mol %) in DCM (1.0 mL) at room temperature. After the full disappearance of methyleneindolinone 1a (monitored by TLC), the reaction mixture was concentrated using rotavap. Crude product was purified using column chromatography.

^bDetermined by ¹H NMR of the crude reaction mixture (3a/4a).

^cIsolated yield of 3a after column chromatography.

^dDetermined by chiral HPLC analysis.

^eEtOAc was used.

^fMTBE was used.

^gCHCl₃ was used.

^hReaction was conducted with 1a (0.10 mmol), 3a (0.15 mmol), and C1 (20 mol %) in CHCl₃ (1.0 mL) at room temperature.

ⁱReaction was conducted with 1a (0.10 mmol), 3a (0.15 mmol), and C1 (1 mol %) in CHCl₃ (1.0 mL) at room temperature.