Table 1. Impact of reaction parameters on catalytic enantioconvergent formal [1,3]-rearrangement ^a .

Entry	Variation from ‘standard’ conditions	Conv. b (%)	Yield b (%)	er c
1	R = H	0	—	—
2	None	>98	90	97.5 : 2.5
3	No CuTC	0	—	—
4	No (R)-L1	0	—	—
5	CuOTf·0.5PhH, instead of CuTC	66	50	77 : 23
6	CuI, instead of CuTC	88	50	47 : 53
7	Cu(MeCN)4BF4, instead CuTC	72	60	46 : 54
8	(R)-L2, instead of (R)-L1	>98	94	96.5 : 3.5
9	(R)-L4, instead of (R)-L1	>98	97	95.5 : 4.5
10	(R)-L5, instead of (R)-L1	>98	95	96.5 : 3.5
11	(R)-L6, instead of (R)-L1	>98	92	96.5 : 3.5
12	(R)-L3, instead of (R)-L1	39	24	19 : 81
13	(R)-L7, instead of (R)-L1	80	40	50 : 50
14	(R)-L8, instead of (R)-L1	<2	—	—
15	THF, instead of PhMe	>98	80	96 : 4
16	Addition of i-Pr2NEt (2.0 equiv.)	>98	82	96.5 : 3.5
17	5 mol% CuTC, 6 mol% (R)-L1 (7 h)	>98	85	97.5 : 2.5
18	–20 °C (1 h), instead of –40 °C	>98	96	96 : 4
19	20 °C (10 min), instead of –40 °C	>98	87	94 : 6

^aAll data are the average of two experiments performed using 0.1 mmol substrate. For entries in which incomplete conversion was observed, reaction times were 24 h.

^bDetermined by analysis of the crude reaction mixtures by ¹H NMR using CH₂Br₂ as an internal standard.

^cDetermined by chiral stationary phase HPLC. CuTC = copper(i)-thiophenecarboxylate. Bn = benzyl.