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. 2023 Jun 22;19:901–908. doi: 10.3762/bjoc.19.68

Table 1.

Screening the optimized reaction conditions.a

graphic file with name Beilstein_J_Org_Chem-19-901-i001.jpg
Entry [Cu] cat. Base Solvent T (°C) Yield (%)b
1c Cu(OTf)2 (10 mol %) DIPEA dioxane/PhCF3 100 24
2c,d Cu(OTf)2 (10 mol %) DIPEA dioxane/PhCF3 100 N.D.
3c Cu(OTf)2 (10 mol %) DIPEA PhCF3 100 N.D.
4c Cu(OTf)2 (10 mol %) DIPEA 1,4-dioxane 100 47
5c Cu(OTf)2 (10 mol %) DIPEA CH2Cl2 100 39
6c CuI (10 mol %) DIPEA 1,4-dioxane 100 41
7c CuCN (10 mol %) DIPEA 1,4-dioxane 100 40
8c Cu2O (10 mol %) DIPEA 1,4-dioxane 100 55
9c / DIPEA 1,4-dioxane 100 N.D.
10c Cu2O (100 mol %) DIPEA 1,4-dioxane 100 72
11c Cu2O (100 mol %) CH3COOK 1,4-dioxane 100 75
12 Cu2O (100 mol %) CH3COOK 1,4-dioxane 100 83
13 Cu2O (100 mol %) CH3COOK 1,4-dioxane 80 54
14 Cu2O (100 mol %) CH3COOK 1,4-dioxane 120 64
15e Cu2O (100 mol %) CH3COOK 1,4-dioxane 100 79

aReaction conditions: A mixture of cyclobutanone oxime (1a, 1.5 mmol, 3.0 equiv), 1,1-diphenylethylene (2a, 0.5 mmol, 1.0 equiv), copper catalyst and base (5.0 mmol, 10.0 equiv) in extra dry solvent (0.1 M) was stirred at the corresponding temperature under an SO2F2 atmosphere (balloon) for 12 h. bThe yield was determined by HPLC using pure 3aa as the external standard (tR = 5.017 min, λmax = 250.0 nm, water/methanol 20:80 (v/v)). c6.0 equiv of base were used. dUnder Ar atmosphere (balloon) instead of SO2F2. eThe reaction lasted 16 h.