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. 2017 Dec 20;83(2):854–861. doi: 10.1021/acs.joc.7b02844

Table 2. Optimization of the Imidoylative Sonogashira/Cyclization Conditionsa.

graphic file with name jo-2017-02844f_0008.jpg

entry Pd source ligand solvent 9a (%)b
1c Pd(PPh3)4 none DMSO nr
2 Pd(PPh3)4 none DMSO 61
3 Pd(PPh3)4 none toluene 27
4 Pd(PPh3)4 none dioxane 13
5 Pd(PPh3)4 none DMF 70
6 Pd/C none DMF nr
7 Pd(OAc)2 PPh3 DMF 82
8 Pd(OAc)2 Bu3P DMF nr
9 Pd(OAc)2 DPEPhos DMF 82
10 Pd(OAc)2 XantPhos DMF 91
11d Pd(OAc)2 XantPhos DMF nr
12e Pd(OAc)2 XantPhos DMF 56
13f Pd(OAc)2 XantPhos DMF nr
14g Pd(OAc)2 XantPhos DMF 31
15 Pd(OAc)2 none DMF nr
16 none XantPhos DMF nr
a

Reaction conditions: 2-bromoaniline (12a, 0.5 mmol, 1 equiv), phenylacetylene (6a, 1 mmol, 2 equiv), tert-butyl isocyanide (7a, 0.625 mmol, 1.25 equiv), catalyst (5 mol %), ligand (monodentate: 15 mol %, bidentate: 10 mol %), CuBr (15 mol %), and Cs2CO3 (1 mmol, 2 equiv) in solvent (3.0 mL) were stirred at 100 °C for 16–20 h under N2 atmosphere.

b

Yields determined by 1H NMR analysis using 2,5-dimethylfuran as internal standard.

c

Reaction performed in the absence of CuBr.

d

KOtBu (2.0 equiv) employed as base.

e

K2CO3 (2.0 equiv) employed as base.

f

Et3N (2.0 equiv) employed as base.

g

DBU (2.0 equiv) employed as base.