Table 3.

Syntheses of Spirooxindoles with N-alkyl groups^a

entry	R1	R2	Pdt(Y%) b	drc (ee %)d
1	Ph	Me	5k (70)	6.5:1:0.5 (99)
2	Ph	Bn	5l (82)	6:1:0.5:0.3 (99)
3	Ph	allyl	5m (84)	7:1:0.4 (99)
4	p-ClPh	allyl	5n (74)	6.5:1:0.3:0.2 (99)
5	p-MePh	allyl	5o (74)	7:1:0.5:0.5 (99)
6	pNO2Ph	allyl	5p (70)	2:1:0.5 (99)

^aGeneral reaction conditions: the reaction was performed by employing 3-olefinic oxindole (0.1 mmol), dialdehyde 2 (50% in water, 0.3 mmol), and organocatalyst A (0.01 mmol) in DMF (0.5 mL) at room temperature for 2 days.

^bIsolated yield.

^cDetermined by ¹H NMR of crude product.

^dThe ee was determined by chiral-phase HPLC analysis of major diastereomer.