Dramatic micellar rate enhancement of the Cu2+ catalyzed vinologous Friedel-Crafts alkylation in water

Article abstract of DOI:10.1039/c0cc02584d

A dramatic rate enhancement of the Cu²⁺ catalyzed Friedel-Crafts alkylation in water was achieved in the presence of sodium dodecyl sulfate (SDS) micelles. The Royal Society of Chemistry.

Full text of DOI:10.1039/c0cc02584d

Supplementary Material (ESI) for Chemical Communications
This journal is (c) The Royal Society of Chemistry 2010
Electronic Supplementary Information
for
Dramatic micellar rate enhancement of the Cu2+ catalyzed
vinologous Friedel-Crafts alkylation in water
Fiora Rosati, Jens Olerich and Gerard Roelfes
Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4,
9747 AG, Groningen, The Netherlands
General remarks
All the substrates were synthesized following published procedures;i 5-methoxyindole, SDS and Cu(NO3)2 were
purchased from Sigma-Aldrich and used without further purification.
Representative procedure for catalytic Friedel-Crafts reactions: An aliquot of a stock solution of Cu(NO3)2
(0.15 mM final concentration) was added to a buffered solution (MOPS 20 mM, pH = 6) of SDS (8 mM final
concentration) in a final volume of 250 mL. To this solution 2-acyl imidazole 1a, b, d (0.30 mmol) and 5-
methoxyindole (1.5 mmol) both dissolved in a minimal amount of DMSO were added consecutively. The reaction
was performed at room temperature and was stopped after 30 min by addition of diethyl ether. The organic layer
was separated and dried over Na2SO4 and concentrated in vacuo. The product was purified by column
chromatography (SiO2 AcOEt: Pentane 1/1).
Kinetic measurements. All kinetic measurements were performed using UV-visible spectroscopy (JASCO V-560
or JASCO V-570 spectrophotometers) monitoring the decrease of the absorption of the dienophile at 25 °C. The
decrease of the absorption at 326 (1c-e) and at 440 nm (1a-b) was followed in time until the reaction was
complete. Pseudo-first-order rate constants were obtained using Grafit 3.0 (Erithacus software Ltd., 1992) to the
exponential equation At=A∞.+ A0·e-kl·t, giving the observed rate constants (kobs) directly. The (kobs) was plotted
against the concentration of 5-methoxyindole, and the kapp was subsequently determined from the slope of this
graph.
Cmc measurement: The measurements were performed under reaction conditions (MOPS buffer, 20 mM, pH = 6
and Cu(NO3)2 0.15 mM) using Lauda Drop-volume tensiometer device.
Fig. S1 Cmc determination of SDS in presence of 0.15 mM Cu(NO3)2
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UV spectra: The UV-Vis spectra were measured on a JASCO V-660 at 25°C
Fig. S2 UV spectra of the substrate 1a / Cu(NO3)2 in absence and in presence of 8 mM SDS
1.5
1.3
0 mM SDS
8 mM SDS
1.1
0.9
0.7
0.5
0.3
0.1
-0.1
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wavelenght (nm)
[Cu2+] = 0.15 mM; [1a] = 0.015 mM
Characterization of products from preparative scale reactions.
1H-NMR-spectra
3-(5-methoxy-1H-indol-3-yl)-3-(4-methoxyphenyl)-1-(1-methyl-1H-imidazol-2-yl)propan-1-one (2a)
δ H (400 MHz, CDCl3) 8.20 (br s, 1H), 7.15 (m, 1H), 7.05 (d, J = 2.2 Hz, 2H), 6.98 (d, J = 2.4 Hz, 1H), 6.92 (s, 1H),
6.79- 6.74 (m, 3H), 4.93 (t, J = 7.6 Hz, 1H), 3.98 -3.92 (dd, J = 16.3, J = 7.1, 1H), 3.89 (s, 3H), 3.84-3.78 (dd, J =
16.3, J = 8.2, 1H), 3.76 (s, 3H), 3.73 (s, 3H).
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Supplementary Material (ESI) for Chemical Communications
This journal is (c) The Royal Society of Chemistry 2010
3-(5-methoxy-1H-indol-3-yl)-1-(1-methyl-1H-imidazol-2-yl)-3-phenylpropan-1-one (2b)
δ H (400 MHz, CDCl3) 8.20 (br s, 1H), 7.36 (d, J = 8.4, 2H), 7.21- 7.18 (m, 2H), 7.18-7.11 (m, 2H), 7.07 (d, J = 2.3
Hz, 1H), 6.98 (m, 1H), 6.91(d, J = 2.4 Hz, 1H), 6.77 (dd, J = 8.8 Hz, J = 2.4 Hz, 1H), 4.98 (t, J = 7.6 Hz, 1H), 4.03-
3.96 (dd, J = 16.4 Hz, J = 7.3 Hz, 1H), 3.89 (s, 3H), 3.86-3.80 (dd, J = 16.4 Hz, J = 7.9 Hz, 1H), 3.75 (s, 3H).
3-(5-methoxy-1H-indol-3-yl)-4-methyl-1-(1-methyl-1H-imidazol-2-yl)pentan-1-one (2d)
δ
H (400 MHz, CDCl3) 7.87 (br s, 1H), 7.16 (d, J = 8.8 Hz, 1H), 7.12 (m, 1H), 7.04 -7.01 (dd, J = 6.1 Hz, J = 2.4
Hz, 2H), 6.93 (s, 1H), 6.80- 6.78 (dd, J = 8.8 Hz, J = 2.3 Hz, 1H), 3.84 (s, 3H), 3.77 (s, 3H), 3.68- 3.56 (m, 2H),
3.45- 3.40 (m, 1H), 2.11- 2.04 (m, 1H), 0.95 (d, J = 4.2 Hz, 3H), 0.93 (d, J = 4.2 Hz, 3H).
i.
D. A. Evans, K. R. Fandrick and H. J. Song, J. Am. Chem. Soc., 2005, 127, 8942-8943; M. C.
Myers, A. R. Bharadwaj, B. C. Milgram and K. A. Scheidt, J. Am. Chem. Soc., 2005, 127, 14675-
14680.
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