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. Author manuscript; available in PMC: 2015 Nov 13.
Published in final edited form as: J Org Chem. 2015 Oct 2;80(19):9584–9591. doi: 10.1021/acs.joc.5b01570

Table 1.

Evaluation of the Conjugate Addition under Lewis Acidic Conditions

graphic file with name nihms724807t1.jpg
entrya Lewis acid 5:8c 5 (%)b
1 no catalyst 1:2.7 9
2 YbCl3 1.15:1 38
3 FeCl3 1.3:1 36
4 Yb(OTf)3 1:3.3 16
5 Gd(OTf)3 1:2.4 29
6 Lu(OTf)3 1:1.7 17
7 Cu(ClO4)2 1:4.3 6
8 Mg(ClO4)2 N/A 0
9 Zn(ClO4)2 N/A 0
10 PdCl2(PhCN)2 N/A 19
11 Ni(ClO4)2·6H2O 4.6:1 74
12 Ni(ClO4)2·6H2O (7 mol %) CH2Cl2:AcOH (6:1) 2.8:1 80
13d Ni(ClO4)2·6H2O (7 mol %) CH2Cl2:AcOH (6:1) 1:0 90
a

Reactions conducted with monoalkylidene 6 (1 equiv) and acylphloroglucinol 7 (1.5 equiv) in 1 mL of CH2Cl2.

b

Yields reported after isolation by silica gel column chromatography.

c

Compound 8 was the only byproduct observed after complete consumption of starting materials. Ratio was determined after isolating both products.

d

Solvents were thoroughly degassed using the freeze–pump–thaw method.