Yields of mixed bis-thiopyrrolizidino dispiro-oxindole 6(A-E)(a-b) derived from curcumin, isatins, proline and thioproline.

Entrya	R1	R2	R3	R4	R5	R6	Product	Yieldb (%)
1	H	H	H	H	OMe	H	6Aa	30
2	H	H	H	H	OMe	H	6Ab	35
3	H	F	H	H	I	H	6Ba	32
4	H	F	H	H	I	H	6Bb	37
5	H	Cl	H	H	I	H	6Ca	31
6	H	Cl	H	H	I	H	6Cb	35
7	H	OMe	H	H	Me	Me	6Da	32
8	H	OMe	H	H	Me	Me	6Db	36
9	H	Me	H	H	Me	Me	6Ea	31
10	H	Me	H	H	Me	Me	6Eb	36

^aUnless otherwise noted, the reaction was performed with 1.76 mmol of 3A-E(a) (±), isatins and thioproline in 50.0 mL of MeOH under reflux for 8 h.

^bDetermined after isolation.