Poly(4-vinylimidazolium)s: A Highly Recyclable Organocatalyst Precursor for. Benzoin Condensation Reaction

Transcription

1 Electronic Supplementary Material (ESI) for RSC Advances. This journal is The Royal Society of Chemistry 24 Supporting Information Poly(4-vinylimidazolium)s: A Highly Recyclable rganocatalyst Precursor for Benzoin Condensation Reaction Ue Ryung Seo and Young Keun Chung* Intelligent Textile System Research Center, and Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 5-747, Korea Contents I. General Information S2 II. General procedure A. Procedure for the synthesis of benzoins and benzils from benzaldehydes S2 B. Procedure for the synthesis of -butyrolactones from benzaldehyde and methyl acrylate S3 III. Recycling Experiment S3 IV. NMR spectra S9

2 Ⅰ. General Information All solvents were obtained by passing through activated alumina columns of solvent purification systems from Glass Contour. n-hexanes and ethyl acetate were used without further purification. Reagents were purchased from Sigma-Aldrich, Alfa Aesar, Acros, TCI and were used as received. Reactions were carried out in a flame - dried glassware equipped with a stirring bar and capped with a rubber septum under N 2, unless otherwise indicated. Elevated temperatures were maintained in thermostat-controlled oil baths. The TLC plate was carried out on.25 mm E. Merck silica gel plates (6-254) visualized by UV-light (254 nm) and treatment with acidic p-anisaldehyde and KMn 4 stain followed by gentle heating. Workup procedures were done in air. lash chromatography was carried out on Merck 6 silica gel (23 4 mesh). IR spectra were measured on a Thermo Scientific Nicolet 67 spectrometer. H and 3 C NMR spectra were recorded with uker (3 MHz) and Varian spectrometer (4 MHz) spectrometer. H NMR spectra were referenced to residual TMS ( ppm) except D 2 (solvent reference, 4.79 ppm) and reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, dd = doublet of doublets, ddd = doublet of doublet of doublets, ddt = doublet of doublet of triplets, dt = doublets of triplets, br s = broad singlet, m = multiplet). Chemical shifts of the 3 C NMR spectra were measured relative to CD 3 (77.6 ppm). Mass spectral data were obtained from the Korea Basic Science Institute (Daegu) on a Jeol JMS 7 high resolution mass spectrometer. Static light scattering (SLS) measurements were measured by Dynamic Light Scattering Spectrophotometer (DLS-7) at National Instrumentation Center for Environmental Management (NICEM), College of Agriculture and Life Sciences, Seoul National University, Korea. II. General Procedure A. Procedure for the Synthesis of Benzoins and Benzils from Benzaldehydes 2 R H H catalyst, DBU + DM R R R benzoin benzil R Reactions were performed in a schlenk tube equipped with a stirring bar and a rubber septum and the followings were placed in the tube in order: 7 mol% of catalyst (3 mg,.3 mmol),.8 mmol of benzaldehyde,.3 eq of DBU (8 μl, 4 mmol) and ml of DM. After the mixture was stirred at 4 o C for 24 h,.45 ml of 4 M H in dioxane solution was added to the reaction mixture. The resulting solution was stirred for an additional h. Addition of excess acetone to the reaction mixture led to precipitae poly(nhc)s. After filtration, the filtrate was concentrated under reduced pressure. Purification by a flash chromatography on silica gel column eluting with n-hexane and ethyl acetate affords benzoin and benzil as products. In a case of pyridine-3- carboxaldehyde, purification was done by using an alumina column eluting with dichloromethane and methanol.

3 *Base screening Isolated yield (%) Entry Base Benzoin Benzil Total t-buk TEA 3 K 2 C DBU C. Procedure for the Synthesis of -Butyrolactones from Benzaldehyde and Methyl Acrylate. R H. precatalyst, DBU, DM, 4 o C, 24 h 2. Me dropping (eq) (5 h) R R + R CH 2 Me H Reactions were performed in a flame-dried 8 ml Schlenk tube equipped with a stirring bar and a rubber septum. The flask was charged with 7 mol% of catalyst (3 mg,.3 mmol),.8 mmol of benzaldehyde, 3 mol% of DBU (8 μl, 4 mmol) and ml of DM. The mixture was stirred at 4 for 24 h. Then, methyl acrylate (.63 ml, 8 mmol) was added, and the reaction mixture was stirred for an additional 5 h. Water was added to the reaction mixture and products were extracted with ethyl acetate 5 times. The organic layer was dried over anhydrous MgS 4 and concentrated under reduced pressure. Purification by flash chromatography on a silica gel column eluting with n-hexane and ethyl acetate afforded -butyrolactones and allylic alcohols, respectively. Ⅲ. Recycling Experiment A Schlenk tube was charged with 7 mol% of catalyst 2 (3 mg,.26 mmol),.3 equiv of DBU (8 μl, 4 mmol), benzaldehyde (.9 g,.8 mmol), and ml of DM. After the mixture was stirred for 24 h at 4 o C, poly(4-vinylnhc)s were successfully recovered by precipitation from the reaction mixture by addition of acetone. The filtrate was immediately introduced to the acid solution to avoid formation of benzil. 4 M H in dioxane solution was used for the acid solution. The solvent was evaporated from the filtrate, and the residue was purified by a flash column chromatograpy. The recovered poly(4-vinylnhc)s were reused for the next run of benzoin condensation reaction. The catalytic performance of poly(4-vinylnhc)s were well maintained during the seven times of the catalyst reuse, leading to benzoin and benzil products in a range of 97-% isolated yields.

4 H NMR, 3 C NMR, HRMS and Melting Point data of Products are Provided: [benzoins] H Benzoin H NMR (4 MHz, CD 3 ) δ (m, 2 H), (t, J = 7.4 Hz, H), 7.39 (t, J = 7.7 Hz, 2 H), (m, 5 H), 5.95 (d, J = 6. Hz, H), 5 (d, J = 6. Hz, H) ppm. 3 C NMR ( MHz, CD 3 ) δ 9, 39., 3, 33.6, 29.2(2), 28.7, 28.6, 27.8, 76.3 ppm. HRMS (EI) calc. for [C 4 H 2 2 ]: 2837, found: m.p.: 3 o C, white solid. H p-methyl benzoin H NMR (4 MHz, CD 3 ) δ 7.72 (d, J = 8.2 Hz, 2 H), 7.2 (d, J = Hz, 2 H), 6 (d, J = 8. Hz, 2 H), (d, J = 7.9 Hz, 2 H), 5.8 (d, J = Hz, H), (d, J = 5.9 Hz, H), 2.22 (s, 3 H), 2.6 (s, 3 H) ppm. 3 C NMR ( MHz, CD 3 ) δ 9, 44.9, 38.3, 36.4, 3.9, 29.8, 29.3(2), 27.6, 75.8, 2.7, 2. ppm HRMS (EI) calc. for [C 6 H 6 2 ]: 24, found: 24. m.p.: 86 o C, white solid. H Me Me p-methoxy benzoin H NMR (3 MHz, CD 3 ) δ 7.89 (d, J = 8.9 Hz, 2 H), 7.24 (d, J = 8.7 Hz, 2 H), 6.83 (dd, J = 8.8, 2.9 Hz, 4 H), 5.85 (d, J = 5.4 Hz, H), 4.6 (d, J = 5.7 Hz, H), 3.78 (s, 3 H), 3.72 (s, 3 H) ppm. 3 C NMR ( MHz, CD 3 ) δ 97.4, 64., 59.7, 3.9, 3.6, 29., 26.4, 4.6,, 75.3, 55.6, 55.3 ppm. HRMS (EI) calc. for [C 6 H 6 4 ]: 2749, found: m.p.: 8 o C, white solid. H p-chloro benzoin H NMR (3 MHz, CD 3 ) δ 7.82 (d, J = 8.4 Hz, 2 H), 7.37 (d, J = 8.4 Hz, 2 H), 7.27 (q, J = Hz, 4 H), 5.88 (s, H), 3 (bs, H) ppm.. 3 C NMR ( MHz, CD 3 ) δ 97.4, 4.6, 37.2, 34.7,, 3.4, 29.4, 29.2, 29., 7 ppm. HRMS (EI) calc. for [C 4 H 2 2 ]: 2858, found: m.p.: 87 o C, white solid. H C 3 3 C p-trifluoromethyl benzoin

5 H NMR (3 MHz, CD 3 ) δ (d, J = 8.2 Hz, 2 H), 7.69 (d, J = 8.3 Hz, 2 H), 7.6 (d, J = 8. Hz, 2 H), 7.45 (d, J = 8. Hz, 2 H), 2 (d, J = 5.9 Hz, H), (d, J = 5.9 Hz, H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 97.8, 42.6, 3, 35.7, 35.3, 3.4,, 2, 28.2, 26.4(q, J = 3.8 Hz), 26.(q, J = 3.6 Hz), 76. ppm. HRMS (EI) calc. for [C 6 H 6 2 ]: 34585, found: m.p.: 93 o C, white solid. H m-omo benzoin H NMR (4 MHz, CD 3 ) δ 6 (s, H), 7.77 (d, J = 7.4 Hz, H), 7.65 (d, J = Hz, H), (m, 2 H), (m, 3 H), 5.86 (s, H), 4.45 (bs, H) ppm. 3 C NMR ( MHz, CD 3 ) δ 97.2, 4.4, 36.9, 34.9, 3.9(2), 3.7, 3.6, 3.3, 2, 26.3, 23.2, 23., 7 ppm. HRMS (EI) calc. for [C 4 H 2 2 ]: , found: m.p.: 57 o C, yellow solid. H p-omo benzoin H NMR (4 MHz, CD 3 ) δ 7.74 (d, J = 8.4 Hz, 2 H), 6 (d, J = 8.6 Hz, 2 H), 7.46 (d, J = 8.8 Hz, 2 H), 7.8 (d, J = 8. Hz, 2 H), 5.86 (d, J = Hz, H), 4.46 (d, J = 6.3 Hz, H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 97.7, 37.7, 3, 32.3, 3, 3.6, 29.6, 29.4, 23., 75.6 ppm. HRMS (EI) calc. for [C 4 H ]: , found: m.p.: 92 o C, white solid. [benzils] Benzil H NMR (4 MHz, CD 3 ) δ 7.98 (d, J = 7.6 Hz, 4 H), 7.67 (t, J = 7.4 Hz, 2H), 2 (t, J = 7.7 Hz, 4 H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 94.7, 3, 33., 3, 29. ppm. HRMS (EI) calc. for [C 4 H 2 ]: 268, found: m.p.: 92 o C, yellow solid. p-methyl benzil H NMR (4 MHz, CD 3 ) δ 7.86 (d, J = 8.2 Hz, 4 H), 7.3 (d, J = Hz, 4 H), 2.43 (s, 6H) ppm. 3 C NMR ( MHz, CD 3 ) δ 94.6, 46.2, 3.8, 3., 29.8, 2 ppm. HRMS (EI) calc. for [C 6 H 4 2 ]: 23994, found: m.p.: 94 o C, yellow solid.

6 p-chloro benzil H NMR (3 MHz, CD 3 ) δ 7.92 (d, J = 8.6 Hz, 4 H), (d, J = 8.6 Hz, 4 H) ppm. 3 C NMR ( MHz, CD 3 ) δ 9, 4.9, 3.4, 3.2, 29.6 ppm. HRMS (EI) calc. for [C 4 H ]: , found: m.p.: 95 o C, yellow solid. C 3 3 C p-trifluoromethyl benzil H NMR (3 MHz, CD 3 ) δ 8.2 (d, J = 8. Hz, 4 H), 7.8 (d, J = 8.3 Hz, 4 H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 9, 36.6, 36., 35.3, 3, 26.3(q, J = 3.7 Hz) ppm. HRMS (EI) calc. for [C 6 H ]: 34428, found: m.p.: 32 o C, white solid. m-omo benzil H NMR (4 MHz, CD 3 ) δ 8.3 (t, J =.8 Hz, 2 H), 7.89 (ddd, J = 7.8,.6,. Hz, 2 H), 7.8 (ddd, J =,,. Hz, 2 H), 7.42 (dd, J =.7, 4. Hz, 2 H) ppm. 3 C NMR ( MHz, CD 3 ) δ 9, 38., 34.4, 32.7, 3.7, 28.7, 2ppm. HRMS (EI) [C 4 H ]: , found: m.p.: 22 o C, yellow solid. p-omo benzil H NMR (3 MHz, CD 3 ) δ 7.84 (d, J = Hz, 4 H), 7.67 (d, J = Hz, 4 H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 92.6, 32.6, 3.6, 3.4, 3.9 ppm. HRMS (EI) [C 4 H ]: , found: m.p.: 22 o C, yellow solid. N N,2-Di(pyridin-3-yl)ethane-,2-dione H NMR (4 MHz, CD 3 ) δ 9.2 (m, 2 H), 8.87 (dd, J = 4.8,.7 Hz, 2 H), 8.32 (dt, J =, Hz, 2 H), 7.49 (dd, J =, 4.9 Hz, 2 H) ppm. 3 C NMR ( MHz, CD 3 ) δ, 55.2,, 37., 28.3, 2 ppm. HRMS (EI) [C 2 H 8 N 2 2 ]:2586, found:2587.

7 [lactones] 5-Benzoyl-5-phenyltetrahydro-2(3H)- furanone H NMR (4 MHz, CD 3 ) δ (m, 2 H), 7.47 (m, 3 H), (m, 2 H), 7.33 (ddd, J =, 4.3,.9 Hz, 3 H), 3.42 (ddd, J =, 8.2, 7. Hz, H), (m, 2 H), 2.33 (dt, J =, 8.4 Hz, H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 95.3, 7, 39.4, 33.6, 3, 3.8, 29.3, 28.6, 28.3, 23.8, 92., 34.4, 2 ppm. HRMS (EI) calc. for [C 7 H 4 3 ]: 26943, found: 2694, colorless oil. 5-(4-Methylbenzoyl)-5-(4-methylphenyl)-tetrahydro-2(3H)-furanone H NMR (4 MHz, CD 3 ) δ (m, 2 H), (m, 2 H), 7.8 (d, J = 7.9 Hz, 2 H), 7.4 (m, 2 H), 3.39 (m, H), 9 (m, 2 H), (m, 7 H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 94.9, 75.8, 44.4, 38.4, 36.7,,, 29.9, 2, 23.7, 92.3, 34.4, 28., 2.7, 2. ppm. HRMS (EI) calc. for [C 9 H 8 5 ]: , found: , colorless oil. Me Me 5-(4-Methoxybenzoyl)-5-(4-methoxyphenyl)-tetrahydro-2(3H)-furanone H NMR (4 MHz, CD 3 ) δ 7.94 (m, 2 H), (m, 2 H), (m, 2 H), (m, 2 H), 3.79 (s, 3 H), 3.77 (s, 3 H), 3.38 (m, H), 8 (m, 2 H), 2.29 (dt, J =, 8.3 Hz, H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 93.7, 75.8, 63.6, 59.6, 33.2, 3.6, 26.3, 25.,,, 9, 55.4, 55.2, 34.3, 2 ppm. HRMS (EI) calc. for [C 9 H 8 5 ]: 324, found: 324, pale-yellow oil. 5-(4-Chlorobenzoyl)-5-(4-chlorophenyl)-tetrahydro-2(3H)-furanone H NMR (4 MHz, CD 3 ) δ (m, 2 H), 7.38 (s, 4 H), (m, 2 H), 3.42 (ddd, J = 3.2, 8.3, 6.8 Hz, H), (m, 2 H), 2.28 (dd, J = 8.6, Hz, H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 93.7, 7, 4.3, 37.7, 34.9, 32., 3.6, 29.6, 28.8, 25.2,, 34.2, 27.9 ppm. HRMS (AB,[M+H]) calc. for [C 7 H ]: 33242, found: 33243, colorless oil.

8 5-(3-omobenzoyl)-5-(3-bromophenyl)-tetrahydro-2(3H)-furanone H NMR (4 MHz, CD 3 ) ) δ 8 (t, J =.8 Hz, H), 7.85 (m, H), 7.62 (m, 2 H), 7.48 (m, H), 7.38 (m, H), (m, 2 H), (m, H), (m, 2 H), (m, H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 93.6, 74.9, 4.3, 36.7, 3, 33.4, 32., 3., 3, 2, 26.9, 23.8, 22.8, 22.4, 9.2, 34.3, 27.9 ppm. HRMS (EI) calc. for [C 7 H ]: , found: , colorless oil. [allylic alcohols] H CH 2 Me Methyl 2-(hydroxy(phenyl)methyl)acrylate H NMR (3 MHz, CD 3 ) δ (m, 5 H), 6.25 (s, H), 5.76 (s, H), 5.47 (s, H), 3.62 (s, 3 H), 8 (s, H) ppm. 3 C NMR ( MHz, CD 3 ) 66.8, 4, 4.3, 2, 27.9, 26.6, 26., 73.2, 5 ppm. HRMS (EI) calc. for [C H 2 3 ]: 9786, found:9783. colorless oil. H CH 2 Me Methyl 2-((3-bromophenyl)(hydroxy)methyl)acrylate H NMR (3 MHz, CD 3 ) δ 7.46 (s, H), 7.34 (d, J = 7.8 Hz, H), 7.23 (d, J = 7.7 Hz, H), (m, H), 6.29 (s, H), 5.77 (s, H), 5.44 (d, J = Hz, H), 3.66 (s, 3 H), 9 (d, J = 5.8 Hz, H) ppm. 3 C NMR (75 MHz, CD 3 ) δ 66.7, 43.7, 4.4, 3., 3, 29.7, 26.9, 25.3, 22.7, 72.9, 52.2 ppm. HRMS (EI) calc. for [C H 3 ]: , found: colorless oil

9 Ⅳ. NMR spectra water H H

10 H H

11 H CH 3 CH H CH 3 CH 3

12 H H

13 H H

14 H H

15 H H

16

17 H 3 C CH H 3 C CH 3

18

19

20 water

21 water

22 N N N N

23 water

24 C H 3 CH C H 3 CH 3

25 CH 3 CH CH 3 CH 3

26 water

27 water

28 H CH 2 CH H CH 2 CH 3

29 H CH 2 CH H