Diastereoselective nitroaldol reaction catalyzed by binuclear copper(II) complexes in aqueous medium

Article abstract of DOI:10.1002/cplu.201402200

Polydentate ligands 1 and 2, which incorporate a terminal pyridyl moiety and an oxygen-rich oxalate dihydrizide/malonic dihydrizide spacer moiety, as well as their binuclear metal complexes [Cu₂1₂] and [Cu₂2₂], which adopt a 1:1 metal/ligand ratio, were synthesized and characterized. Both complexes were screened for their catalytic activity in the nitroaldol reaction, in which [Cu₂1₂] worked efficiently as catalyst for both substituted benzaldehyde and pyridinecarboxaldehyde, whereas [Cu₂2₂] is highly substrate specific and showed activity towards nitro-substituted aldehydes and pyridinecarboxaldehyde. Furthermore, as helicates are intrinsically chiral, the stereochemical architecture in the binuclear double-stranded Cu₂helicates as catalyst favored the diastereoselective syn product with nitroethane and nitropropane and their respective diastereoselectivities were determined by using ¹H NMR spectroscopy.

Full text of DOI:10.1002/cplu.201402200

Supporting Information
ꢀ Copyright Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, 2014
Diastereoselective Nitroaldol Reaction Catalyzed by
Binuclear Copper(II) Complexes in Aqueous Medium
Rajendran Arunachalam,[a, b] Chirayil S. Aswathi,[a] Anjan Das,[a, b] Rukhsana I. Kureshy,[a, b] and
Palani S. Subramanian*[a, b]
cplu_201402200_sm_miscellaneous_information.pdf

Content
Spectral data for Complexes----------------------------------------------------- 02-04
Characterization of Nitroaldol products---------------------------------------- 05-07
1H-NMR spectra for Nitroaldol product----------------------------------------- 08-15
1

General
All starting materials and reagents were used as received without any further purification. 200 MHz or 500 MHz
spectrometers were used for the 1H and 13C NMR spectra. Chemical shifts were reported in ppm from
tetramethylsilane with the solvent resonance as the internal standard (CDCl3=7.26). Spectra are reported as
follows: chemical shift (ppm), multiplicity (s = singlet, d = doublet, t =triplet, q = quartet, m = multiplet), coupling
constants (Hz), integration, and assignment.
Spectral data for Complexes
S1. LCMS for Ligand-1
S2. LCMS for Ligand-1
2

S3. LCMS for [Cu212]
S4. LCMS for [Cu222]
3

S5. IR for [Cu212]
S6. IR for [Cu222]
4

S7. Charterization of Nitroaldol product
1
2-nitro-1-(4-nitrophenyl)ethanol: Yellow oil, Yield 92%; H- NMR
(200 MHz, CDCl3):  = 8.28-8.24 (d, 2H), 7.65-7.61(d, 2H), 5.65-5.59
(t, 1H), 4.68-4.54 (m, 2H), 3.38 (bs, 1H).
2-nitroethanol-1-phenylethanol: Colorless oil, Yield 83%;
1H- NMR (200 MHz, CDCl3)  = 7.28 (s, 5H), 5.34-4.29
(t, 1H), 4.48-4.39 (m, 2H), 3.12 (bs, 1H).
1
1-(4-fluorophenyl)-2-nitroethanol: Yellow oil, Yield 98%; H- NMR
(200 MHz, CDCl3)  = 7.43-7.36 (m, 2H), 7.14-7.06 (m, 2H), 5.49-5.43
(m, 1H), 4.58-4.51 (dd, 2H), 2.30 ( bs, 1H).
1
1-(4-chlorophenyl)-2-nitroethanol: Yellow oil, Yield 92%; H- NMR
(200 MHz, CDCl3)  = 7.44-7.36 (m, 2H), 7.15-7.04 (m, 2H), 5.49-5.43
(m, 1H), 4.58-4.51 (dd, 2H), 1.66 (bs, 1H).
1
1-(4-bromophenyl)-2-nitroethanol: Yellow oil, Yield 56%; H- NMR
(200 MHz, CDCl3)  = 7.55-7.51 (d, 2H), 7.30-7.26 (d, 2H), 5.48-5.39
(m, 1H), 4.56-4.50 (t, 2H), 3.09 (bs, 1H).
1
1-(3-bromophenyl)-2-nitroethanol: Colorless oil, Yield 89%; H- NMR
(200 MHz, CDCl3)  = 7.59-7.48 (t, 2H), 7.30-7.33 (m, 2H), 5.47-5.43 (t,
1H), 4.65-4.53 (m, 2H), 3.00 (bs, 1H).
1
4-chloro-2-(1-hydroxy-2-nitroethyl)phenol: Yellow oil, Yield 26%; H-
NMR (200 MHz, CDCl3)  = 8.09-8.05 (d, 1H), 7.97-7.94 (d, 1H), 7.79-
7.72 (t, 1H), 4.91-4.89 (d, 1H), 4.84-4.82 (d, 1H), 4.61-4.50 (m, 1H),
3.45 (bs, 1H), 1.85 (bs, 1H).
1
2-nitro-1-(2-nitrophenyl)ethanol: Yellow oil, Yield 90%; H- NMR (200
MHz, CDCl3)  = 8.03-7.98 (d, 1H), 7.91-7.87 (d, 1H), 7.72- 7.64
(t,
1H),7.52-7.45 (t, 1H), 5.99-5.95 (d, 1H), 4.84-4.76 (dd, 1H), 4.54-4.43
(m, 1H), 3.32 (bs, 1H).
5

1
2-nitro-1-(pyridine-2-yl)ethanol: Brown oil, Yield 92%; H- NMR: (200
MHz, CDCl3)  = 8.59-8.57 (d, 1H), 7.82-7.73 (t, 1H), 7.46-7.43 (d, 1H),
7.34-7.27 (t, 1H), 5.51-5.45 (dd, 1H), 4.84-4.59 (m, 1H), 1.71 (bs, 1H).
1
2-nitro-1-phenylpropan-1-ol: Colorless oil, Yield 83%; de 64%; H-
NMR (200 MHz, CDCl3)  = 7.36 (s, 5H), 5.02-4.97 (d, 1H), 4.83-4.72
(m, 1H), 3.00 (bs, 1H), 1.31-1.47 (dd, 3H).
2-nitro-1-(4-nitrophenyl)propan-1-ol: Yellow oil, Yield 93%; de 45 %;
1H- NMR (200 MHz, CDCl3)  = 8.28-8.24 (d, 2H), 7.61-7.57 (d, 2H),
5.22-5.17 (d, 1H), 4.86-4.69 (m, 1H), 3.14 (bs, 1H), 1.51-1.47 (d, 1H),
1.41-1.37 (d, 2H).
1-(4-fluorophenyl)-2-nitropropan-1-ol: Yellow oil, Yield 94%; de
49%; 1H- NMR (200 MHz, CDCl3)  = 7.31-7.24 (dd, 2H), 7.05-7.01 (d,
2H), 4.97-4.92 (d, 1H), 4.69-4.61 (m, 1H), 2.99 (bs, 1H), 1.24-1.21 (d,
3H).
1-(4-chlorophenyl)-2-nitropropan-1-ol: Yellow oil, Yield 85%; de 24%;
1H- NMR (200 MHz, CDCl3)  = 7.41-7.29 (m, 4H), 5.05-5.01 (d, 1H),
4.79-4.60 (m, 1H), 2.75 (bs, 1H), 1.51-1.48 (d, 1H), 1.35-1.31 (d, 2H).
1
2-nitro-1-(pyridin-2-yl)propan-1-ol: Brown oil, Yield 92%; de 96%; H-
NMR: (200 MHz, CDCl3)  = 8.57-8.55 (d, 1H), 7.80-7.72 (t, 1H), 7.37-
7.33 (t, 2H), 5.07-5.03 (d, 1H), 4.95-4.85 (m, 1H), 1.44-1.40 (d, 3H).
1
2-nitro-1-(4-nitrophenyl)butan-1-ol: Yellow oil, Yield 91%; de 40%; H-
NMR (200 MHz, CDCl3)  = 8.29-8.25 (d, 2H), 7.60-7.56 (d, 2H), 5.02-
5.16 (d, 1H), 4.67-4.56 (m, 1H), 2.90 (bs, 1H), 1.94-1.89 (m, 1H), 1.56-
1.45 (m, 1H), 0.96-0.89 (m, 3H).
1
2-nitro-1-(pyridin-2-yl)butan-1-ol: Brown oil, Yield 89%; de 100%; H-
NMR (200 MHz, CDCl3)  = 8.60-8.58 (d, 1H), 7.76-7.75 (d, 1H), 7.37-
7.31 (t, 2H), 5.05-5.02 (d, 1H), 4.81-4.74 (m, 1H), 3.44 (bs, 1H), 2.08-
1.99 (m, 1H), 1.08-1.59 (m, 1H), 0.98-0.91(m, 3H).
1
2-nitro-1-(pyridin-4-yl)butan-1-ol. Brown oil, Yield 92%; de 15%; H-
NMR: (200 MHz, CDCl3)  = 8.76-8.74 (d, 1H), 7.97-7.94 (d, 1H), 7.76-
7.69 (t, 2H), 5.07-5.03 (d, 1H), 4.59-4.54 (m, 1H), 1.83-1.72 (q, 2H), 0.99-
0.90(m, 3H).
6

2-nitro-1-(4-nitrophenyl)propan-1-ol: Yellow oil, Yield 94%; de 19%; 1H-
NMR (200 MHz, CDCl3)  = 8.29-8.24 (d, 2H), 7.62-7.56 (d, 2H), 5.21-5.17
(d, 1H), 4.81-4.70 (m, 1H), 3.05 (bs, 1H), 1.51-1.48 (d, 1H), 1.41-1.37 (d,
2H).
2-nitro-1-(pyridin-2-yl)propan-1-ol: Brown oil, Yield 94%; de 92%;1H-
NMR: (200 MHz, CDCl3)  = 8.51 (s, 1H), 7.72-7.64 (t, 1H), 7.49-7.38 (m,
1H), 7.28-7.19 (t, 1H), 5.00-4.97 (d, 1H), 4.91-4.78 (m, 1H), 1.38-1.35 (d,
3H).
2-nitro-1-(pyridin-3-yl)propan-1-ol: Brown oil, Yield 92%; de 32%; 1H-
NMR: (500 MHz, CDCl3)  = 8.56-8.54 (d, 2H), 7.79-7.77 (d, 1H), 7.38-
7.36 (t, 1H), 5.11-5.09 (d, 1H), 4.82-4.76 (m, 1H), 1.53-1.52 (d, 1H), 1.37-
1.35 (d, 2H).
2-nitro-1-(pyridin-4-yl)propan-1-ol: Brown oil, Yield 92%; de 40%; 1H-
NMR: (500 MHz, CDCl3)  = 7.71-7.70 (d, 2H), 7.53-7.52 (d, 2H), 5.15-
5.05 (d, 1H), 4.70-4.66 (m, 1H), 1.48-1.46 (d, 3H).
1
2-nitro-1-(4-nitrophenyl)butan-1-ol: Yellow oil, Yield 95%; de 16%; H-
NMR (200 MHz, CDCl3)  = 8.23-8.18 (d, 2H), 7.53-7.49 (d, 2H), 5.13-5.09
(d, 1H), 4.60-4.49 (m, 1H), 1.25-1.84 (m, 2H), 0.98-0.82 (t, 3H).
1
2-nitro-1-(pyridin-2-yl)butan-1-ol: Brown oil, Yield 95%; de 92%; H-
NMR (200 MHz, CDCl3)  = 8.57-8.55 (d, 1H), 7.77-7.69 (t, 1H), 7.35-7.25
(m, 2H), 5.03-4.99 (d, 1H), 4.79-4.72 (m, 1H), 2.01-1.96 (m, 1H), 1.66-
1.59 (m, 1H), 0.95-0.88 (m, 3H).
1
2-nitro-1-(pyridin-3-yl)butan-1-ol: Brown oil, Yield 92%; de 33%; H-
NMR (500 MHz, CDCl3)  = 8.54-8.50 (d, 2H), 7.79-7.77 (d, 1H), 7.38-
7.36 (t, 1H), 5.09-5.07 (d, 1H), 4.64-4.58 (m, 1H), 1.45-1.36 (m, 2H), 0.92-
0.89 (d, 3H).
1
2-nitro-1-(pyridin-4-yl)butan-1-ol: Brown oil, Yield 86%; de 36%; H-
NMR (500 MHz, CDCl3)  = 7.71-7.70 (d, 1H), 7.54-7.53 (d, 1H), 7.33-
7.32 (d, 2H), 5.05-5.04 (d, 1H), 4.62-4.54 (m, 1H), 1.36-1.31 (m, 2H), 0.95-
0.92 (t, 3H).
7

1H NMR spectra for nitroaldol product
Table. 1(Entry-17).
OH
NO2
O2N
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
Table. 3(Entry-1)
OH
NO2
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
8

Table. 3(Entry-2).
OH
NO2
F
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
Table. 3(Entry-3)
OH
NO2
Cl
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
9

Table. 3(Entry-4).
OH
NO2
Br
8.0
ppm (t1)
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
Table. 3(Entry-5).
OH
N
NO2
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
10

Table. 3(Entry-6).
OH
NO2
Br
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
Table. 3(Entry-7).
OH
OH
Cl
NO2
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
11

Table. 4(Entry-1).
OH
NO2
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
Table. 4(Entry 2).
OH
NO2
O2N
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
12

Table. 4(Entry-4).
OH
NO2
Cl
8.0
ppm (t1)
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
Table. 4(Entry-5).
OH
N
NO2
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
13

Table. 4(Entry-6).
OH
NO2
O2N
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
Table. 4(Entry-7).
OH
N
NO2
5.0
0.0
ppm (t1)
14

Figure. 3(Entry-2).
OH
N
NO2
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
Figure. 3(Entry-3).
OH
NO2
N
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
ppm (t1)
15