Synthesis of dihydrofuran-fused spirooxindole^a.

Entry	R1	R2	Yieldb (%) (7/10)	d.r.c
1d	H	Ph	15/74	10 : 1 (10a)
2	H	2-FC6H4	13/66	16 : 1 (10b)
3	H	4-FC6H4	11/68	16 : 1 (10c)
4	H	3,4-Cl2C6H3	12/71	8 : 1 (10d)
5	H	4-BrC6H4	10/75	10 : 1 (10e)
6	H	2-CH3C6H4	8/78	20 : 1 (10f)
7	H	4-OCH3C6H4	Trace/81	18 : 1 (10g)
8	H	Thienyl	15/60	5 : 1 (10h)
9	H	Naphthyl	15/62	5 : 1 (10i)
10	H	CH3	14/74	6 : 1 (10j)
11	H	OEt	13/76	5 : 1 (10k)
12	5-F	Ph	8/70	10 : 1 (10l)
13	7-F	Ph	Trace/56	16 : 1 (10m)
14	5-Cl	Ph	14/66	5 : 1 (10n)
15	6-Cl	Ph	12/67	15 : 1 (10o)
16	5-Br	Ph	10/70	13 : 1 (10p)
17	6-Br	Ph	10/69	10 : 1 (10q)
18	5-CH3	Ph	8/80	18 : 1 (10r)
19e	H	Ph	12/80	9 : 1 (10a)

^aUnless otherwise noted, all reactions were performed with 3 (0.15 mmol), 4 (0.165 mmol) in 2 mL DCM at 50 °C for 4 h.

^bIsolated yields of the compound 7 and 10.

^cThe diastereoselective ratio of compounds 10 were determined by ¹H-NMR analysis of the crude reaction mixture.

^dThe relative configuration of 10a was determined by X-ray crystallographic analysis (Fig. 2), and the relative configurations of other products 10 were tentatively assigned by analogy.

^eA gram scale reaction of 3a (3.13 mmol) and 4a (3.44 mmol) in DCM at 50 °C was carried out.