Nature Communications

Table 1 Optimized conditions for the reaction^a.

From: Brønsted acid-enhanced copper-catalyzed atroposelective cycloisomerization to axially chiral arylquinolizones via dearomatization of pyridine


Entry	Catalyst	Ligand	Solvent	Additives	t (h)	Yield (%)^b	Ee (%)^c
1	AgOTf	L1	DCE	–	0.5	70	29
2	CuBF₄	L1	DCE	–	72	50	36
3	CuCl	L1	DCE	–	72	51	73
4	CuCl	L1	THF	–	72	38	69
5	CuCl	L1	MeCN	–	72	34	56
6	CuCl	L1	Toluene	–	72	45	76
7	CuCl	L2	Toluene	–	72	30	20
8	CuCl	L3	Toluene	–	72	35	46
9	CuCl	L4	Toluene	–	72	56	69
10	CuCl	L5	Toluene	–	72	30	35
11^d	CuCl	L1	Toluene	–	72	51	90
12^d	CuCl	L1	Toluene (2.0 mL)	–	72	70	90
13^d	CuCl	L1	Toluene (3.0 mL)	–	72	58	90
14^d	CuCl	L1	Toluene	(R)-CPA	36	88	92
15^d	CuCl	L1	Toluene	TsOH	36	67	90
16^d	CuCl	L1	Toluene	PhCOOH	36	57	90
17^d	CuCl	L1	Toluene	(R)-CPA (0.5 eq)	36	83	91
18^d	CuCl	L1	Toluene	(R)-CPA (0.2 eq)	36	76	90
19^d	CuCl	L1	Toluene	NaBAr_F	72	26	13
20^d	CuCl	L1	Toluene	DBU	72	N.D.^e	N.D.^e

^aReaction conditions: 1a (0.1 mmol), catalyst (10 mol%), ligand (15 mol%), solvent (1.0 mL), 20 °C.
^bYields of isolated products.
^cEe values were determined by chiral HPLC.
^d1b was used as the substrate.
^eN.D. = Not detected. Compound 1b was decomposed.

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