Table 6.

Asymmetric Betti reaction of 6-hydroxyquinoline (17) with ketimine 18 catalyzed by thioureas 1–7 or thiosquaramides 8–11.

Entry	Catalyst	Temp. [°C]	Yield [%] 1	ee [%] 2 (Conf.) 3
1	1	20	68	76 (S)
2	1	0	60	87 (S)
3	2	20	55	66 (S)
4	3	20	65	92 (S) 4
5	4	20	55	74 (S)
6	5	20	68	66 (S)
7	6	20	68	76 (R)
8	7	20	78	90 (R)
9	7	0	75	98 (R)
10	8	20	50	8 (R)
11	8·HCl	20	35	12 (R)
12	9	20	50	12 (S)
13	9·HCl	20	40	14 (S)
14	10	20	65	2 (R)
15	10·HCl	20	45	6 (R)
16	11	20	65	10 (R)
17	11·HCl	20	40	2 (R)

Reagents and conditions: 6-hydroxyquinoline (0.1 mmol, 1 eq.), ketimine (0.1 mmol, 1 eq.), 5 mol% cat., toluene (1 mL), molecular sieves 4 Å, 48 h. ¹ Isolated product. ² Determined by HPLC analysis, Chiralpak AD-H, hexane:iPrOH 80:20, 1 mL/min, 235 nm. ³ The configuration was established by comparison with the optical rotation from the literature [17]. ⁴ Lit. [17] ee = 93%.