Table 2.

Synthesis of spiro[5,8-methanoquinazoline-2,3′-indoline]-2′,4-dione derivatives 3a–p ^a.

Entry	Amide	Ketone	Time (h)	Product	Yield b (%)	de c (Major/Minor)
1	1a	2a	6	3a	42	1:0
2	1a	2b	5	3b	46	1:0
3	1a	2c	6	3c	29	1:0
4	1a	2d	6	3d	30	1:0
5	1b	2a	12	3e d	35	1:0
6	1b	2b	10	3f	37	1:0
7	1b	2c	24	3g d	30	1:0
8	1b	2d	24	3h d	28	1:0.3
9	1c	2a	5	3i	45	1:0
10	1c	2b	5	3j	42	1:0
11	1c	2c	6	3k	24	1:0
12	1c	2d	6	3l	38	1:0.4
13	1d	2a	14	3m	31	1:0
14	1d	2b	20	3n	24	1:0.4
15	1d	2c	24	3o e	25	1:1
16	1d	2d	24	3p e	34	1.3:1

^a A mixture of the corresponding isatin (0.13 mmol), β-amino amide (0.13 mmol), alum (20 mg, 30 mol%), and EtOH (5 mL) was stirred under reflux for the specified time. ^b Isolated yield after purification by flash chromatography. ^c The diastereoselectivity major/minor ratio was calculated by NMR measurements. ^d A mixture of the corresponding isatin (0.13 mmol), β-amino amide (0.13 mmol), I₂ (19 mg, 30 mol%), and EtOH (5 mL) was stirred under reflux for the specified time. ^e A mixture of corresponding isatin (0.13 mmol), β-amino amide (0.13 mmol), NH₄Cl (5 mg, 30 mol%), and 2M2B (5 mL) was stirred under reflux for the specified time.