Optimisation of catalytic conditions for diastereodivergent [4 + 2] annulations^aa.

Entry	L	Solvent	Additive	Yieldb (%)	drc	eed (%)
1	L1	Toluene	—	Trace	—	—
2	L2	Toluene	—	Trace	—	—
3	L3	Toluene	—	4a, 62	>19 : 1	75
4	L4	Toluene	—	4a, 82	>19 : 1	93
5	L5	Toluene	—	4a, 30	4 : 1	71
6	L6	Toluene	—	4a, 73	10 : 1	93
7	L7	Toluene	—	4a, 95	>19 : 1	98
8e	L7	Toluene	—	4a, 95	>19 : 1	98
9f	L7	Toluene	—	4a, 50	>19 : 1	98
10	L8	Toluene	—	Messy	—	—
11	L9	Toluene	—	Messy	—	—
12	L10	Toluene	—	5a, 92	<1 : 19	82
13	L11	Toluene	—	Trace	—	—
14	L10	THF	—	5a, 51	1 : 10	80
15	L10	Dioxane	—	5a, 35	1 : 11	82
16	L10	CHCl3	—	5a, 20	1 : 2	89
17	L10	Toluene	A1	5a, 33	<1 : 19	83
18	L10	Toluene	A2	5a, 76	<1 : 19	80
19	L10	Toluene	A3	5a, 75	<1 : 19	80
20g	L10	Toluene	—	5a, 25	<1 : 19	82
21h	L10	Toluene	—	5a, 56	<1 : 19	83

^aUnless noted otherwise, reactions were carried out with 1a (0.1 mmol), 2a (0.05 mmol), Pd₂(dba)₃ (5 mol%), L (20 mol%) in toluene (0.5 mL) at 60 °C for 36 h under Ar.

^bYield of the isolated product.

^cThe ratio of 4a/5a, determined from ¹H NMR analysis of crude products.

^dDetermined from HPLC analysis on a chiral stationary phase.

^eL7 (10 mol%).

^fWith Pd₂(dba)₃ (2.5 mol%).

^gWith L10 (10 mol%).

^hAt 50 °C, for 72 h.