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. Author manuscript; available in PMC: 2011 Jun 19.
Published in final edited form as: Tetrahedron. 2010 Jun 19;66(25):4423–4427. doi: 10.1016/j.tet.2010.04.044

Table 2.

Tandem Michael-Henry reaction between 1,2-diones and nitroalkenesa

graphic file with name nihms-196836-f0005.jpg
entry R1 R2 R3 R4 drb yield (%)c eed (%)
1 -(CH2)3- H Ph(3a) 88:12 75 97
2 -(CH2)3- H 4-MeC6H4(3b) 92:8 83 97
3 -(CH2)3- H 4-MeOC6H4(3C) 88:12 82 97
4 -(CH2)3- H 4-ClC6H4(3d) 86:14 68 96
5 -(CH2)3- H 4-BrC6H4(3e) 94:6 89 97
6 -(CH2)3- H 4-CNC6H4(3f) 91:9 79 97e
7 -(CH2)3- H 4-NO2C6H4(3g) 94:6 90 93e
8 -(CH2)3- H 2-MeOC6H4(3h) 95:5 87 94
9 -(CH2)3- H 2-BrC6H4(3i) 72:28 66 92
10 -(CH2)3- H 3-ClC6H4(3j) 88:12 77 96e
11 -(CH2)3- H graphic file with name nihms-196836-t0006.jpg 92:8 89 99e
12 -(CH2)3- H n-C6H13(3l) 88:12 77 97
13 -(CH2)3- Me Ph (3m) 88:12 67f 97
14 Me H H Ph --- 0 ---
15 -(CH2)2- Me Ph --- 0g ---
a

All reactions were conducted with trans-nitroalkenes (0.25 mmol), 1,2-diones (0.30 mmol), and catalyst 4 (15 mmol %) in toluene (1.5 mL) at room temperature for 26 to 32 h (TLC monitoring).

b

Diastereomeric ratio was determined by 1H NMR analysis of the crude mixture.

c

Yield of the isolated major diastereomer after column chromatography.

d

Unless otherwise specified, ee values were determined by HPLC analysis on a ChiralCel OJ-H column.

e

Determined by HPLC analysis on a ChiralPak AD-H column.

f

The reaction time was 72 h.

g

A complex mixture of unidentified products was obtained.