Electronic Supplementary Information
Chemoselective transfer hydrogenation of α,β-unsaturated carbonyls using palladium immobilized ionic liquid catalyst
Nilesh M. Patil,aTakehikoSasakib and Bhalchandra M. Bhanagea*
aDepartment of Chemistry, Institute of Chemical Technology, N. Parekh Marg, Matunga, Mumbai-400019,India.
E-mail:;;Fax: +91-22-3361-1020.
bDepartment of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8561, Japan.
Sr.no. / Content1 / General information
2 / Preparation of ImmPd-IL.
3 / General experimental procedure
4 / Recyclability study of catalyst
5 / Characterisation data
6 / 1H and 13C NMR Spectra
1) General information.
3-trimethoxysilylpropyl chloride,N-methylimidazoleand anhydrous redistilled 1-methylimidazole were procured from Aldrich.PdCl2andall the dry solvents were purchased from WAKO.Aerosil 300 (300 m2/g) was acquired from Japan Aerosil Co. and calcined at 573 K for 1.5 hin air and 30 min in vacuum before use as support. The catalyst ImmPd-IL prepared according toour previous reports with some modifications[19-22]. The catalyst was characterized by using elemental analysis, FTIR and loading of the catalyst was calculated by XRF measurements (SEA-2010, Seiko Electronic Industrial Co.). The XPS analysis of ImmPd-IL using a PHI5000 Versa Probe with a monochromatic focused (100 µm × 100 µm) Al Kα X-ray radiation (15 kV, 30 mA) and dual beam neutralization using a combination of Argon ion gun and electron irradiation.The crude products were isolated and purified by column chromatography on silica gel (100-200 mesh size).All the products are well known in literature and were characterized and confirmed by GC (Perkin Elmer, Clarus 400) (BP-10 GC column, 30 m x 0.32 mm ID, film thickness 0.25 mm), GCMS (Shimadzu GC-MS QP 2010), 1H NMR (Avance-II, Bruker, 400 Mhz) and 13C NMR spectra (100 MHz).
2. Preparation of ImmPd-IL.
The preparation of immobilized palladium ion-containing ionic liquid catalyst is as given below(scheme 2).
Scheme 2.The Preparation of palladium metal-ion-containing immobilizedionic liquid.
In a dry round bottom flask, 3-trimethoxysilylpropyl chloride (0.690 mol) and N-methylimidazole (0.690 mol) were added undernitrogen atmosphere and resulting reaction mixture was refluxed for 48 h. After completion, the reaction mixture was cooled to room temperature, washed with dry ethyl acetate for five times. The obtained residue was dried at room temperature under reduced pressure for 2 days and then stored at 253 K under dry nitrogen condition.
In the next step, 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride and silica (Aerosil 300, surface area 300 m2 g-1, calcined at 573 K for 1.5 h in air) (weight ratio 1 : 1) were added in a round bottom flask containing dry toluene and were refluxed for 48 h under nitrogen atmosphere. Thereafter, the reaction mixture was cooled at room temperature; the resulting mass was filtered by using glass filter. The obtained residue was washed several times with dichloromethane to remove the excess ionic liquid. This obtained residue was denoted as Imm-IL. In the last step, PdCl2 and Imm-IL were added in acetonitrile and reaction mixture was refluxed for 48 h. The resulting suspension was filtered by using glass filter and washed with acetone till removal of excess metal chloride and acetonitrile. The metal loading of ImmPd-IL was determined by XRF measurements and was found 3.4 wt%.
3.General experimental procedure.
The round bottom flask containing α,β-unsaturated carbonyl (1 mmol), HCOONH4 (3 mmol ) and ImmPd-IL (2 mol%) was added toluene (10 ml) and RM heated at 90 oC for 12 h. The progress ofthe reaction was monitored by using TLC and GC analysis. After completion, the reaction mixture was cooled to room temperature and the reaction mixture was filtered to separate catalyst. The filtrate was then evaporated under high vacuum rotary evaporator.The obtained residue was then purified by column chromatography using silica gel (100-200 mesh size) with pet ether and ethyl acetate (95:5) to give the desired pure product. All products are well known in literature and were characterised by GCMS, 1H NMR,13C NMR spectroscopy.
4. Typical experimental procedure for recycling of ImmPd-IL.
In order to make our catalytic system more economical, we have studied the reusability of ImmPd-IL catalyst for standard reaction of benzylideneacetophenone, HCOONH4 as a hydrogen source in toluene. After completion of the reaction the reaction mixture was filtered through sintered funnel to separate solid ImmPd-IL. The separated catalyst was then washed twice with toluene followed by distilled water and finally with methanol to remove the rest organic residue, the catalyst was then dried under vacuum with reduced pressure prior to the next reuse. The recyclability study shows that the catalyst could efficiently recycle up to four consecutive cycles without significant lose on in catalytic activity giving moderate to good conversion and selectivity (Fig. 1). To check the leaching of palladium in solution from solid immobilized support, we have performed ICP-AES analysis of first and forth recycle run, the result shows that palladium content in solution was below detectable level (0.001ppm). We have also performed hot filtration test to check the Pd leaching. The experimental result suggests that the palladium metal did not leach from the Imm-IL support at elevated temperature during the progress of reaction.
5. Spectral data of the products.
1) 1, 3-Diphenyl-propan-1-one
1H NMR (400 MHz, CDCl3) δ = 7.94 (d, J = 8.3, 1.2 Hz, 2H), 7.53 (t, 1H), 7.44 (t, 2H), 7.24 (m, J = 12.9, 8.6, 7.3 Hz, 5H), 3.29 (t, J=7.78 Hz, 2H), 3.06 (t, J=7.77 Hz, 2H); 13C NMR (101 MHz, CDCl3) δ = 199.27, 141.33, 136.86, 133.12, 128.65, 128.58, 128.48, 128.08, 126.18, 40.49, 30.15; GC-MS (EI) m/z (%) = 210(38) [M]+, 106(9), 105(100), 91(12), 77(42), 51(11).
2) 3-phenyl-1-(p-tolyl)propan-1-one
1H NMR (400 MHz, CDCl3) δ = 7.85 (d, J = 8.2 Hz, 2H), 7.28-7.17 (m, J = 7.1 Hz, 8H), 3.26 (t, J = 8Hz, 2H), 3.05 (t, J = 7.8Hz, 2H), 2.42 (s, 3H); 13C NMR (101 MHz, CDCl3) δ = 198.94, 143.88, 141.43, 134.39, 129.32, 128.55, 128.46, 128.20, 126.13, 40.38, 30.23, 21.67; GC-MS (EI) m/z (%) = 224 [M]+, 209, 119, 105, 91, 65, 51.
3) 3-(4-Methoxy-phenyl)-1-phenyl-propan-1-one
1H NMR (400 MHz, CDCl3) δ = 7.93 (d, J = 9.0 Hz, 2H), 7.24 (m, J = 9.0,5H), 6.91 (d, J = 9.0 Hz, 2H), 3.86 (s, 3H), 3.24 (t, J = 7.9 Hz, 2H), 3.05 (t, 2H); 13C NMR (101 MHz, CDCl3) δ= 197.86, 163.47, 141.49, 130.33, 129.96, 128.53, 128.46, 126.11, 113.74, 55.49, 40.15, 30.34; GC-MS (EI) m/z (%) =240(40) [M]+, 135(12), 122(9), 121(100), 108(18), 105(47), 77(41), 78(8), 51(8).
4) 1-Phenyl-3-thiophen-2-yl-propan-1-one
1H NMR (400 MHz, CDCl3) δ= 7.96 (d, J = 7.1 Hz, 2H), 7.56 (t, 1H), 7.46 (t, J = 8.2, 7.0 Hz, 2H), 7.12 (dd, J = 5.1, 1.2 Hz, 1H), 6.92 (dd, J = 5.1, 3.4 Hz, 1H), 6.86 (dd, J = 3.4, 1.0 Hz, 1H), 3.37 (m, 2H), 3.29 (m, 2H); 13C NMR (101 MHz, CDCl3) δ= 198.62, 143.90, 136.73, 133.21, 128.66, 128.05, 126.88, 124.71, 123.41, 40.57, 24.22; GC-MS (EI) m/z (%) =216(51) [M] +, 111(56), 110(14), 105(100), 97(64), 84(10), 77(75), 51(21), 45(13).
5 )3-Furan-2-yl-1-phenyl-propan-1-one
1H NMR (400 MHz, CDCl3) δ= 7.97(d, J=8 Hz, 2H), 7.54 (t, J=7.6 Hz, 1 H), 7. 46 (d,J=7.6 Hz,2H), 7.28(d,J=7.6 Hz,1H), 6.28 (d ,J=8 Hz,1H), 6.05 (d, J= 2.8 Hz,1H), 3.33 (t, J= 7.2,2H,), 3.09 (t, J= 7.2,2H); 13C NMR(101 MHz, CDCl3 ) δ =198.69, 154.77, 141.13, 136.72, 133.18, 128.65, 128.05, 110.27 105.34,36.95, 22.51;GC-MS (EI) m/z (%) =200(45) [M] +, 144(6), 106(9), 105(100), 95(35), 94(11), 91(14), 77(65), 53(12), 51(20).
6)Ethyl 3-phenylpropanoate
1H NMR (400 MHz, CDCl3) δ = 7.28 ( d, J = 7.6 Hz, 2H), 7.19 (m, J = 7.4 Hz, 3H), 4.12 (q, J = 7.1 Hz, 2H), 2.95 (t, 2H), 2.62 (t, J = 8.5, 7.3 Hz, 2H), 1.23 (t, J = 7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ = 172.97, 140.59, 128.49, 128.32, 126.25, 60.45, 35.98, 30.99, 14.23. GC-MS (EI) m/z (%) = 178 [M] +, 133, 104, 91, 77, 65, 51.
7) 3-phenylpropanamide
1H NMR (400 MHz, CDCl3) δ = 7.51 (d, J = 7.5 Hz, 2H), 7.31 (m, J = 7.2 Hz, 3H), 5.78 (bs, 1H), 5.48 (bs,1H), 2.96 (t, 2H), 2.52 (t, 2H);13C NMR (101 MHz, CDCl3) δ = 174.77, 141.49, 128.60, 128.33, 126.33, 37.56, 31.41. MS (EI) m/z (%) = 149 [M]+, 132, 115, 104, 77, 65, 51.
6) 1H and 13C NMR spectra
1) 1, 3-Diphenyl-propan-1-one
2) 3-phenyl-1-(p-tolyl)propan-1-one
3)3-(4-Methoxy-phenyl)-1-phenyl-propan-1-one
4) 1-Phenyl-3-thiophen-2-yl-propan-1-one
5) 3-Furan-2-yl-1-phenyl-propan-1-one
6) Ethyl 3-phenylpropanoate
7) 3-phenylpropanamide