Table 1. Screening of different Ligands.
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Entry a | [Pd] | Ligand | Conv. (%) | 2a : 3 : 4 b |
1 | Pd[P(t-Bu)3]2 | Full | 44 : 56 : 0 | |
2 | Pd2(dba)3 | L1, SPhos | 46 | 83 : 0 : 17 |
3 | Pd2(dba)3 | L2, CPhos | 38 | 87 : 0 : 13 |
4 | Pd2(dba)3 | L3, XPhos | Full | >99 : 0 : 0 |
5 | Pd-PEPPSI-IPent | Full | 96 : 0 : 4 |
aConditions: (3-methylbut-2-en-2-yl)lithium (0.40 mmol, 0.6 M in THF) was added to a solution of 1a (0.3 mmol) and catalyst in toluene (1 mL), 1 h addition time.
b 2a : 3 : 4 ratios determined by GC analysis. dba = dibenzylideneacetone.