Chiral functionalization of a zirconium metalorganic. catalyst in asymmetric Michael addition reaction

Transcription

1 Electronic supplementary material for paper Chiral functionalization of a zirconium metalorganic framework (DUT-67) as a heterogeneous catalyst in asymmetric Michael addition reaction Khoa D. Nguyen, Christel Kutzscher, Franziska Drache, Irena Senkovska,* and Stefan Kaskel* Department of Inorganic Chemistry, Dresden University of Technology, Bergstraße 66, Dresden, Germany Table of content 1. Exchange of formate by L-proline in DUT-67-fa... S2 2. Catalytic studies... S NMR spectra of the product... S Effect of catalyst amount and additives on the catalytic activity... S8 3. Elemental and thermogravimetric analysis... S ICP-OES... S TGA curves... S9 4. HPLC... S11 References... S12 S1

2 1. Exchange of formate by L-proline in DUT-67-fa As shown in previous studies, an 8-connected Zr 6 -node is typically coordinated by four monocarboxylate anions in addition to the linker to achieve an idealized 12 connected node (typical, for example, for UiO-66 and UiO-67). 1 However, the accessibility/possibility to exchange the monocarboxylates (M) is clearly influenced by various factors, including solvent polarity, the size of MOF crystals as well as the nature of monocarboxylates. 2-3 In most of the reports describing solvent assisted monocarboxylates exchange in zirconium based MOFs, the pristine compound is usually subjected to a washing step with HCl solution to remove pristine monocarboxylates and to create free terminal OH groups prior to functionalization. These free hydroxyl groups act as important anchoring points to decorate Zr cluster. 4-5 However, it was recently observed that HCl treatment is not needed when using fluorinated monocarboxylates, such as trifluoroacetate, pentafluorobenzoate to replace formate anions as modulators in DUT To calculate the amount of L-proline incorporated into DUT-67-fa the ratios of L-proline, formate or DMF to 2,5-thiophene dicarboxylate were determined by 1 H-NMR after digestion of DUT-67- fa crystals. Table S1. Degree of L-proline functionalization. N Sample Molar ratio L-proline Formate DMF Average number of molecules per cluster Molar ratio Average number of molecules per cluster Molar ratio Average number of molecules per cluster 1 12 h h h h h h Used in 2 catalytic cycles 8 HCl treated S2

3 Figure S1. 1 H-NMR spectrum of digested DUT-67 after soaking it for 12 h in L-proline solution Figure S2. 1 H-NMR spectrum of digested DUT-67 after soaking it for 24 h in L-proline solution. S3

4 Figure S3. 1 H-NMR spectrum of digested DUT-67 after soaking for 48 h in L-proline solution Figure S4. 1 H-NMR spectrum of digested DUT-67 after soaking for 72 h in L-proline solution. S4

5 Figure S5. 1 H-NMR spectrum of digested DUT-67 after soaking for 96 h in L-proline solution Figure S6. 1 H-NMR spectrum of digested DUT-67 after soaking for 120 h in L-proline solution. S5

6 Figure S7. 1 H-NMR spectrum of digested DUT-67 after HCl treatment Figure S8. 1 H-NMR spectrum of digested DUT-67 sample used in two catalytic cycles. S6

7 2. Catalytic studies 2.1. NMR spectra of the product 2-(2-Nitro-1-phenylethyl)cyclohexan-1-one: 1 H-NMR (300 MHz, CDCl 3 ) δ: (m, 5H), 4.85 (dd, 1H), 4.56(dd, 1H), 3.70(dt, 1H), (m, 1H), (m, 2H), (m, 1H), (m, 4H), (m, 1H). 13 C-NMR (100 MHz, CDCl 3 ) δ: , , , , , 77.21, , 42.31, 33.19, 28.50, MS (M + H + ) Figure S9. 1 H-NMR spectrum of 2-(2-nitro-1-phenylethyl)cyclohexan-1-one. Figure S C-NMR spectrum of 2-(2-nitro-1-phenylethyl)cyclohexan-1-one. S7

8 2.2. Effect of catalyst amount and additives on the catalytic activity Table S2. The effect of catalyst and additive amounts on the catalytic performance. N Temp. Catalyst/subtrate ratio (%) Additive Amount of additive (%) Yield determined by GC (%) syn/anti ee (%) 1 50 o C 5% o C 10% o C 20% : RT 15% RT 15% CH 3 COOH 10% 66 95: o C 15% : o C 15% CH 3 COOH 10% 99 91: o C 15% HCOOH 10% 99 89:11 28 Benzoic 9 50 o C 15% acid 10% 92 92:8 29 (*) The reaction was carried out in the mixture of ethanol and IPA, using 20 equivalent of cyclohexanone, in the presence of DUT-67-pro containing approximately 4 molecules L-proline per zirconium node. (**) The catalyst amount based on L-proline content. GC yield / % % 10% 5% Time / h Figure S11. The effect of catalyst amount on the rate of the Michael addition reaction. The sample with four L-proline molecules per cluster was used. The catalyst amount (in wt.%) refers to the L-proline content in the sample. S8

9 3. Elemental and thermogravimetric analysis 3.1. ICP-OES Table S3. Zirconium content. N Sample Chemical formula (*) Zr / wt.% calculated Zr / wt.% measured 1 As made DUT-67-fa Zr 6 O 6 (TDC) 4 (OH) 2 (HCOO) DMF. 1.2(HCOOH) DUT-67-H Zr 6 O 6 (TDC) 4 (OH) As made DUT-67-pro Zr 6 O 6 (TDC) 4 (OH) 0.08 (Pro) DUT-67-pro used in Zr 6 O 6 (TDC) 4 (OH) 0.08 (Pro) two catalytic cycles (*) Based on 1 H-NMR spectra 3.2. TGA curves The thermogravimetric analysis (TG) was performed on a STA 409 PC Luxx (Netzsch) thermal analyser in argon flow with a heating rate of 5 C/min (range: C). a) Weight loss (%) Remaining mass 39.50% Derivative weight (%/min) Temperature ( C) S9

10 b) Weight loss (%) Remaining mass 37.14% Derivative weight (%/min) c) Temperature ( C) Weight loss (%) Remaining mass 32.19% Derivative weight (%/min) Temperature ( C) Figure S12. (a) TGA curve of DUT-67-fa, (b) TGA curve of DUT-67-pro, (c) TGA curve of reused DUT-67-pro. S10

11 4. HPLC N. Retention time Area Note syn-product anti-adduct anti-adduct syn-adduct Racemic mixture Figure S13. HPLC spectrum of the 2-(2-nitro-1-phenylethyl)cyclohexan-1-one enantiomers produced in the presence of DL-proline as catalyst. S11

12 N. Retention time Area Note syn-product anti-adduct anti-adduct syn-adduct (Peak N.4) Figure S14. HPLC spectrum of the 2-(2-nitro-1-phenylethyl)cyclohexan-1-one enantiomers produced in the presence of DUT-67-pro as catalyst in isopropanol. References 1. Deria, P.; Mondloch, J. E.; Tylianakis, E.; Ghosh, P.; Bury, W.; Snurr, R. Q.; Hupp, J. T.; Farha, O. K., Perfluoroalkane Functionalization of NU-1000 via Solvent-Assisted Ligand Incorporation: Synthesis and CO2 Adsorption Studies. J. Am. Chem. Soc. 2013, 135, Drache, F.; Bon, V.; Senkovska, I.; Marschelke, C.; Synytska, A.; Kaskel, S., Postsynthetic Inner-Surface Functionalization of the Highly Stable Zirconium-Based Metal Organic Framework DUT-67. Inorg. Chem. 2016, 55, Deria, P.; Bury, W.; Hupp, J. T.; Farha, O. K., Versatile functionalization of the NU-1000 platform by solvent-assisted ligand incorporation. Chem. Commun. 2014, 50, Deria, P.; Bury, W.; Hod, I.; Kung, C.-W.; Karagiaridi, O.; Hupp, J. T.; Farha, O. K., MOF Functionalization via Solvent-Assisted Ligand Incorporation: Phosphonates vs Carboxylates. Inorg. Chem. 2015, 54, Marshall, R. J.; Forgan, R. S., Postsynthetic Modification of Zirconium Metal-Organic Frameworks. Eur. J. Inorg. Chem. 2016, 2016, S12