Electronic Supplementary Material (ESI) for ChemComm. This journal is © The Royal Society of Chemistry 2020 Supporting information Lewis acid–base synergistic catalysis of cationic halogen-bonding-donors with nucleophilic counter anions Koki Torita,a Ryosuke Haraguchi,*b Yoshitsugu Morita,a Satoshi Kemmochi,a Teruyuki Komatsu,a and Shin-ichi Fukuzawa*a aDepartment of Applied Chemistry, Institute of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, 112-8551 Tokyo, Japan bDepartment of Applied Chemistry, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan. Contents Instrumentation and Chemicals S2 Effect of Counter Anions on the Catalytic Activity S4 Effect of Water on the Catalytic Efficiency S4 NMR Titration Experiment S5 Experimental Procedure S7 Characterization Data S11 Theoretical Study S18 NMR Spectra Data S38 References S77 S1 Instrumentation and Chemicals All manipulations of oxygen- and moisture-sensitive materials were conducted under argon or nitrogen atmosphere in a flame dried Schlenk flask. Nuclear magnetic resonance spectra were taken on a JEOL ECA spectrometer using tetramethylsilane for 1 H NMR as an internal standard (δ = 0 ppm) when CDCl3 was used as a solvent, using 1 CD3CN for H NMR as an internal standard (δ = 1.94 ppm) when CD3CN was used as a 1 solvent, using (CD3)2SO for H NMR as an internal standard (δ = 2.50 ppm) when 13 (CD3)2SO was used as a solvent, using CDCl3 for C NMR as an internal standard (δ = 13 77.16 ppm) when CDCl3 was used as a solvent, using CD3CN for C NMR as an internal standard (δ = 118.26 ppm) when CD3CN was used as a solvent, using (CD3)2SO 13 for C NMR as an internal standard (δ = 39.52 ppm) when (CD3)2SO was used as a solvent. 1H NMR, 13C NMR, and 19F NMR data are reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, quint = quintet, sext = sextet, sept = septet, br = broad, m = multiplet), coupling constants (Hz), and integration. High-resolution mass spectra (HRMS) were measured by a JEOL JMS-T100LC AccuTOF. Infrared (IR) spectra were measured by an FT/IR-4100ST spectrometer. Potassium hexafluorophosphate was purchased from Tokyo Chemical Industry Co., Ltd. (P1023, >95%). tert-Butyl hypochlorite was purchased from Tokyo Chemical Industry Co., Ltd. (H0362, >98%). Potassium tert-butoxide was purchased from Tokyo Chemical Industry Co., Ltd. (P1008, >97%). Ethynylbenzene was purchased from Tokyo Chemical Industry Co., Ltd. (E0196, >98%). 4-Chlorobenzaldehyde was purchased from Tokyo Chemical Industry Co., Ltd. (C0125, >97%). 4-Acetylbenzaldehyde was purchased from Sigma-Aldrich Co. LLC (516333, 97%). Trimethylsilyl cyanide was purchased from Tokyo Chemical Industry Co., Ltd. (T0990, >96%). Iodine was purchased from nacalai tesque (19220-95, >99.8%). 4-Methoxybenzaldehyde was purchased from Tokyo Chemical Industry Co., Ltd. (A0480, >99%). N-(4-Methoxybenzylidene)aniline was purchased from Tokyo Chemical Industry Co., Ltd. (M0582, >98%). Styrene oxide was purchased from Tokyo Chemical Industry Co., Ltd. (E0013, >98%). Carbon dioxide was purchased from TOMOE SHOKAI Co.,LTD. (3407-a, >99.9%). Tetrahydrofuran was purchased from Kanto Chemical Co., Inc. (40993-95, >99.5%). Dichloromethane was purchased from Kanto Chemical Co., Inc. (10158-81, >99%), distilled from calcium hydride and stored under nitrogen. Unless otherwise noted, commercially available reagents were used without purification. 1,3-Bis(2,6-diisopropylphenyl)triazene[1], 1,3-bis(2,4,6-trimethylphenyl)triazene[1], 1,3-diphenyltriazene[2], 1-ethynyl-4-trifluoromethylbenzene[3], 4-ethynyltoluene[3], S2 4-ethynylanisole[3], 2-ethynyl-1,3-diisopropylbenzene[3], 1-ethynyl-2,4,6-trimethylbenzene[3], were prepared according to the literature. S3 Effect of Counter Anions on the Catalytic Activity (a) iodide vs tetrafluoroborate O OTMS catalyst (0.5 mol %) H + TMSCN CN (1.5 eq) CH2Cl2, 30 °C, 1 h Cl Cl 6a 7a CF3 CF3 with 5aa-I: 99% with 5aa-BF4: 49% i-Pr i-Pr N N i-Pr I I i-Pr I BF4 N N N N i-Pr i-Pr i-Pr i-Pr 5aa-I 5aa-BF4 (b) iodide vs hexafluorophosphate O OTMS catalyst (0.5 mol %) H + TMSCN CN (1.5 eq) CH2Cl2, 30 °C, 1 h Cl Cl 6a 7a with 5af-I: 47% with 5af-PF6: 26% i-Pr i-Pr N N i-Pr I I i-Pr I PF6 N N N N i-Pr i-Pr i-Pr i-Pr 5af-I 5af-PF6 Scheme. S1 Investigation of the effect of counter anions of cationic XB-donors 5 on the catalytic activity for the cyanosilylation of aldehyde 6a. Effect of Water on the Catalytic Efficiency O H2O (1.5 eq) OTMS 5aa-I (0.5 mol %) H + TMSCN CN (1.5 eq) CH2Cl2, 30 °C, 1 h Cl Cl 6a 7a trace Scheme. S2 Investigation of the effect of water on the catalytic activity for the cyanosilylation of aldehyde 6a. S4 NMR Titration Experiment 13 13 Fig. S1 (a) C NMR spectra of 5aa-I with 10 equivalents of 6a in CDCl3. (b) C NMR spectra of 1 1 5aa-I in CDCl3. (c) H NMR spectra of TMSCN with 1 equivalent of 5aa-I in CDCl3. (d) H NMR spectra of TMSCN in CDCl3. S5 1 1 Fig. S2 (a) H NMR spectra of TMSCN with 1 equivalent of (n-Bu)4I in CDCl3. (b) H NMR spectra of TMSCN in CDCl3. S6 Experimental Procedure General procedure for preparation of 1,3,4-triaryl-1H-1,2,3-triazolium salts 3 2 KPF6 (2.3 eq) Ar t-BuOCl (2.3 eq) Ar1 1 N 1 N Ar Ar + H N N 2 N H Ar CH2Cl2, –78 °C N to rt, 17 h PF6 1 1 (1.5 eq) 2 Ar 3 Following the reported procedure,[4] the reaction was performed in a 50-mL Schlenk flask equipped with a magnetic stirring bar and a septum. To a solution of triazene 1 (3.0 mmol) and potassium hexafluorophosphate (4.6 mmol, 0.85 g) in dichloromethane (10 mL) was added tert-butyl hypochlorite (4.6 mmol, 0.50 g) at −78 °C, and the resulting mixture was stirred at the same temperature for 30 min. Then, alkyne 2 (2.0 mmol) was added to the reaction mixture at −78 °C. The mixture was allowed to warm to room temperature and stirred for the additional 17 h. The resulting mixture was filtered through a pad of Celite, and the pad was rinsed with dichloromethane. The filtrate was concentrated in vacuo. Diethyl ether was added to the residue, the precipitate was filtered to give 1,3,4-triarylated-1H-1,2,3-triazolium salts 3. General procedure for preparation of 1,3,4-triaryl-1H-5-iodo-1,2,3-triazolium salts 5 Ar2 1) t-BuOK (1.5 eq) Ar2 Ar1 THF, 0 °C, 3 h Ar1 N N H I I N N 2) I2 (3.0 eq), 30 °C, 17 h N N PF6 Ar1 Ar1 3 5 The reaction was performed in a 50-mL Schlenk flask equipped with a magnetic stirring bar and a septum. 1,3,4-triaryl-1H-1,2,3-triazolium salts 3 (1.0 mmol) was dissolved in THF (10 mL) under a nitrogen atmosphere, and the mixture was cooled to 0 °C. To a stirred solution potassium was added tert-butoxide (1.5 mmol, 0.17 g), and the mixture was stirred at 0 °C for 3 h. To the reaction mixture was added iodine (3.0 mmol, 0.76 g) at 0 °C, and the mixture was allowed to warm to 30 °C. After being stirred for 17 h, the mixture was poured into a saturated aqueous solution sodium thiosulfate. The resulting mixture was extracted with dichloromethane. The combined organic layers were washed S7 with water and brine, dried over sodium sulfate, and concentrated in vacuo. To the residue was added the mixture of Et2O/acetone (5/1), and the precipitate was filtered to give the corresponding 1,3,4-triaryl-1H-5-iodo-1,2,3-triazolium salts 5. Procedure for preparation of 5aa-BF4 CF3 CF3 i-Pr i-Pr N AgBF4 (1.5 eq) N i-Pr I I i-Pr I BF N N 4 N CH2Cl2, rt, 18 h N i-Pr i-Pr i-Pr i-Pr 5aa-I 5aa-BF4 79% yield The reaction was performed in a 50-mL Schlenk flask equipped with a magnetic stirring bar and a septum. Silver tetrafluoroborate (1.1 mmol) and iodotriazolium iodide 5aa-I (0.7 mmol) were dissolved in dichloromethane (10 mL) under a nitrogen atmosphere. After the mixture was stirred at room temperature for 18 h in the dark, the mixture was filtered through a pad of Celite. The filtrate was concentrated in vacuo to give 5aa-BF4 in 79% yield. S8 General procedure for the reaction of 6a with trimethyl silylcyanide O OTMS catalyst (0.5 mol %) H + TMSCN CN (1.5 eq) CH2Cl2, 30 °C, 1 h Cl Cl 6a 7a To a 1-mL vial were added sequentially 6a (0.20 mmol, 28 mg), TMSCN (0.30 mmol, 30 mg), catalyst (0.0010 mmol), and dichloromethane (0.20 mL). After the vial was purged with argon and capped, the reaction mixture was stirred at 30 °C for 1 h. And then, the mixture was passed through a short silica gel pad. The filtrate was concentrated under reduced pressure, affording an yellowish oil. Yields were calculated based on the 1H NMR analysis of the crude reaction mixture using dibromomethane as the internal standard. Procedure for the reaction of 6c with trimethyl silylcyanide O TMSCN (1.5 eq) OTMS OTMS catalyst (0.5 mol %) H CN + CN CH2Cl2, 30 °C, 1 h NC O 6c O OTMS 7c 8c To a 1-mL vial were added sequentially 6c (0.20 mmol, 30 mg), TMSCN (0.30 mmol, 30 mg), catalyst (0.0010 mmol), and dichloromethane (0.20 mL) After the vial was purged with argon and capped, the reaction mixture was stirred at 30 °C for 1 h.