Table 2.

Discovery and evaluation of the Cu-catalyzed asymmetric cascade process^a.

Entry	Catalyst	Ligand	Solvent (mL)	Additive (equiv)	Yield (%)b	er c
1	Co(acac)2	Xantphos	THF (0.2)	—	76	—
2	Co(acac)2	(R,R)-Walphos	THF (0.2)	—	33	39:61
3	Co(acac)3	(R,R)-Walphos	THF (0.2)	—	28	35:65
4	Cu(acac)2	(R,R)-Walphos	THF (0.2)	—	20	76:24
5	Cu(acac)2	(R,S)-Josiphos	THF (0.2)	—	25	32:68
6	Cu(acac)2	(R)-tol-BINAP	THF (0.2)	—	15	45:55
7	Cu(acac)2	(S,S)-Me-duphos	THF (0.2)	—	n.d.	—
8	Cu(acac)2	(R,R)-Me-ferrocelane	THF (0.2)	—	n.d.	—
9	Cu(acac)2	(R,R)-Walphos	Cyclohexane (1.0)	—	33	88:12
10	Cu(acac)2	(R,R)-CH3-Walphos	Cyclohexane (1.0)	—	16	72:28
11	Cu(acac)2	(R,R)-tBu-Walphos	Cyclohexane (1.0)	—	17	62:38
12	Cu(acac)2	(R,R)-CF3-Walphos	Cyclohexane (1.0)	—	18	86:14
13	Cu(acac)2	(R,R)-Nap-Walphos	THF (0.2)	—	23	84:16
14d	Cu(acac)2	(R,R)-Walphos	Cyclohexane (1.0)	PMHS (1.0)	78	94:6

^aAfter catalyst (4 mol%), ligand (4 mol%), HBdan (0.24 mmol) were mixed in 0.2 mL of THF at room temperature for 15 min, HBpin (0.3 mmol) and 1 (0.2 mmol) were added subsequently at room temperature, then the resulting mixture was stirred at ambient temperature for 24 h.

^bIsolated yield.

^cThe enantioselectivity was determined by Chiral HPLC.

^dAfter catalyst (6 mol%), ligand (6 mol%), HBdan (0.24 mmol) and PMHS (1.0 equiv) were mixed in 1.0 mL of cyclohexane at room temperature for 10 min, HBpin (0.3 mmol) and 1 (0.2 mmol) were added subsequently at room temperature, then the resulting mixture was stirred at ambient temperature for 60 h.