Table 7.

The synthesis of trans‐3 with various catalysts.^[a]

Entry	Catalyst [mol %]	t [h]	Conv. [%][b]	Selectivity trans‐3 [%]	trans/ cis 3
1	A (2)+[Bu4N]Br (3)	4.5	68	76	1:0
2	A (1)+[Bu4N]Br (3)	4.5	56	77	1:0
3	A (1)+[Bu4N]Br (3)	24	91	64	1:0
4	A (5)	4.5	83	72	1:0
5	[Bu4N]Cl (3)	4.5	35	82	1:0
6	[Bu4N]Br (3)	4.5	45	59	1:0
7	[Bu4N]I (3)	4.5	15	52	1:0
8	Aliquat 336[c] (3)	4.5	34	69	1:0
9	A (2)+[Bu4N]Cl (3)	4.5	83	78	1:0
10	A (2)+[Bu4N]I (3)	4.5	55	39	1:0
11	A (2)+[Bu4N]Cl (3)	24	93	74	1:0
12	A (2)+[Bu4N]Br (3)	24	96	55	1:0
13	A (2)+[Bu4N]I (3)	24	98	67	1:0
14	none	4.5	–[d]	–	–

[a] Reaction conditions: trans‐2 (2.0—2.6 mmol) (see the Supporting Information IVc), 140 °C, 75 bar CO₂ at 40 °C, biphenyl (10 mol %) as an internal standard, stirrer speed 300 rpm. [b] Determined from quantitative ¹H NMR spectroscopy. [c] Aliquat 336=commercial mixture of C₈ and C₁₀ quaternary ammonium salts with predominately N‐methyl‐N,N,N‐trioctylammonium chloride. [d] 5 % mass loss.