Supporting Information

Transcription

1 Palladium-Catalyzed Cascade Oxidantion/sp 2 C-H Acylation of Azoarenes with Aryl Methanes Feng Xiong, a Cheng Qian, b Dongen Lin, b Wei Zeng b,* and Xiaoxia Lu a,* a Chengdu Institute of Biology,CAS, Chengdu , P R.China b School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou , P R.China luxx@cib.ac.cn; zengwei@scut.edu.cn Supporting Information Table of Contents 1. General methods General procedure for preparation of substituted azobenzene substrates... 2 a) General procedure for the synthesis of 1-a~1-h:... 2 b) General procedure for the synthesis of 1-i:... 4 c) General procedure for the synthesis of 1-j:... 4 d) General procedure for the synthesis of 1-k:... 4 e) General procedure for the synthesis of 1-l:... 5 f) General procedure for the synthesis of 1-m:... 5 g) General procedure for the synthesis of 1t:... 6 h) General procedure for the synthesis of 4: General procedure for reaction condition screening The mechanism exploration of Pd-catalyzed ortho-acylation of azobenzene with toluene Characterization data of coupling products References H and 13 C NMR spectra of the products

2 1. General methods Unless otherwise noted, all reagents were purchased from commercial suppliers and used without purification. Toluene was distilled from sodium under nitrogen. Purifications of reaction products were carried out by flash chromatography using silica gel (40-63 mm). Infrared spectra (IR) were recorded on a FT-IR spectrophotometer and are reported as wavelength numbers (cm -1 ). Infrared spectra were recorded by preparing a KBr pellet containing the title compound. 1 H and 13 C NMR spectra were recorded with TMS as internal standard at ambient temperature unless otherwise indicated on a standard spectrometer operating at 400 MHz for 1 H and 100 MHz for 13 C. Chemical shifts are reported in parts per million (ppm) and coupling constants are reported as Hertz (Hz). Splitting patterns are designated as singlet (s), broad singlet (bs), doublet (d), triplet (t), quartet (q). Splitting patterns that could not be interpreted or easily visualized are designated as multiplet (m).melting points were determined on a microscopic melting point apparatus and are uncorrected. Low resolution mass spectra were taken on a GC-MS instrument. High resolution mass spectra (HRMS) were recorded on an IF-TOF spectrometer (Micromass). Compounds described in the literatures were characterized by comparison of their 1 H, and 13 C NMR spectra to the previously reported data. 2. General procedure for preparation of substituted azobenzene substrates a) General procedure for the synthesis of 1-a~1-h: The mixture of CuBr (4.2 mg, 0.03 mmol), pyridine (8.7 mg, 0.09 mmol) and arylamine (1 mmol) in toluene (4 ml) was vigorously stirred at 60 C under air (1 atm) for 20 h. Then cooling down to room temperature and concentrating in vacuum, the residue was purified by flash chromatography on a short silica gel (eluent: petroleum ether) to afford the desired product. [1] (E)-1, 2-Di-p-tolyldiazene (1-a) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ 7.81 (d, J = 8.2 Hz, 4H), 7.30 (d, J = 8.2 Hz, 4H), 2.42 (s, 6H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , 21.46; MS (EI,70 ev): m/z = [M + ]. (E)-1, 2-Di-m-tolyldiazene (1-b) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ (m, 4H), 7.40 (t, J = 7.9 Hz, 2H), 7.28 (d, J = 7.4 Hz, 2H), 2.46 (s, 6H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , 21.36; MS (EI,70 ev): m/z = [M + ]. 2

3 (E)-1, 2-Di-o-tolyldiazene (1-c) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ 7.61 (d, J = 7.9 Hz, 2H), (m, 4H), (m, 2H), 2.73 (s, 6H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , 17.67; MS (EI,70 ev): m/z = [M + ]. (E)-1, 2-Bis (4-chlorophenyl) diazene (1-d) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ 7.86 (d, J = 8.6 Hz, 4H), 7.49 (d, J = 8.6 Hz, 4H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , ; MS (EI, 70 ev): m/z = [M + ]. (E)-1, 2-Bis (4-bromophenyl) diazene (1-e) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ (d, J = 8.8 Hz, 4H), 7.66 (d, J = 8.8 Hz, 4H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , ; MS (EI, 70 ev): m/z = [M + ]. (E)-1,2-Bis (4-fluorophenyl) diazene (1-f) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ (m, 4H), (m, 4H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm (d, J = Hz), (d, J =2.2 Hz), (d, J =9.0 Hz), (d, J =22.9 Hz); MS (EI,70 ev): m/z = [M + ]. (E)-1, 2-Bis (4-methoxyphenyl) diazene (1-g) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ 7.88 (d, J = 8.9 Hz, 4H), 7.00 (d, J = 8.9 Hz, 4H), 3.88 (s, 6H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , 55.55; MS (EI,70 ev): m/z = [M + ]. 3

4 (E)-Diethyl 4,4'-(diazene-1,2-diyl) dibenzoate (1-h) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ 8.21 (d, J = 8.4 Hz, 4H), 7.98 (d, J = 8.4 Hz, 4H), 4.43 (q, J = 7.1 Hz, 4H), 1.43 (t, J = 7.1 Hz, 6H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , 61.37, 14.33; MS (EI,70 ev): m/z = [M + ]. b) General procedure for the synthesis of 1-i: The mixture of CuBr (2.9 mg, 0.02 mmol), pyridine (4.8 mg, 0.06 mmol), aniline (93 mg, 1 mmol) and 4-methoxybenzenamine (0.2 mmol) in toluene (4 ml) was vigorously stirred at 60 C under O 2 (1 atm) for 24 h. Then cooling down to room temperature and concentrating in vacuum, the residue was purified by flash chromatography on silica gel (eluent: petroleum ether/ethyl acetate = 200:1) to afford 1-i. [1] (E)-1-(4-Methoxyphenyl)-2-phenyldiazene (1-i) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ 7.92 (d, J = 8.8 Hz, 2H), 7.88 (d, J = 7.2 Hz, 2H), (m, 3H), 6.99(d, J = 8.8 Hz, 2H), 3.85 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , 55.60; MS (EI,70 ev): m/z = [M + ]. c) General procedure for the synthesis of 1-j: The mixture of CuBr (2.9 mg, 0.02 mmol), pyridine (4.8 mg, 0.06 mmol), p-toluidine (93 mg, 1 mmol) and 4-methoxybenzenamine (0.2 mmol) in toluene (4 ml) was vigorously stirred at 60 C under O 2 (1 atm) for 24 h. Then cooling down to room temperature and concentrating in vacuum, the residue was purified by flash chromatography on silica gel (eluent: petroleum ether/ethyl acetate = 200:1) to afford 1-j. [1] (E)-1-(4-Methoxyphenyl)-2-p-tolyldiazene (1-j) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ 7.90 (d, J = 8.9 Hz, 2H), 7.79 (d, J = 8.2 Hz, 2H), 7.29 (d, J = 8.2 Hz, 2H), 7.00 (d, J = 8.9 Hz, 2H), 3.88 (s, 3H), 2.42 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , 55.58, 21.45; MS (EI,70 ev): m/z = [M + ]. d) General procedure for the synthesis of 1-k: The mixture of CuBr (2.9 mg, 0.02 mmol), pyridine (4.8 mg, 0.06 mmol), aniline (93 mg, 1 mmol) and ethyl 4-aminobenzoate (0.2 mmol) in toluene (4 ml) was vigorously stirred at 60 C under O 2 (1 atm) for 24 h. Then cooling down to room temperature and concentrating in vacuum, the residue was purified by flash chromatography on silica gel (eluent: petroleum ether/ethyl acetate = 200:1) to afford 1-k. [1] 4

5 (E)-Ethyl 4-(phenyldiazenyl) benzoate (1-k) [1] : 1 H NMR (400 MHz, CDCl 3 ) δ 8.19 (d, J = 8.5 Hz, 2H), (m, 4H), (m, 3H), 4.41 (q, J = 7.1 Hz, 2H), 1.42 (t, J = 7.1 Hz, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , 61.28, 14.35; MS (EI,70 ev): m/z = [M + ]. e) General procedure for the synthesis of 1-l: 50 ml of a 3% sodium hypochlorite solution in water were added dropwise to an ice cooled solution of 3-aminopyridine (3.00 g, 31.9 mmol) dissolved in 55 ml water. The solution was stirred for 45 min at 5-10 C. Then the corresponding crude product was extracted with ethyl acetate (3 15 ml). The combined organic layers were dried over magnesium sulphate, then filtrated and remove the solvent, the corresponding crude product was purified by column chromatography on silica gel (ethyl acetate) to afford 1-l. [2] 3, 3 -Azopyridine (1-l) [2] : 1 H NMR (400 MHz, CDCl 3 ) δ 9.23 (s, 2H), 8.74 (d, J = 4.5 Hz, 2H), 8.17 (d, J = 8.0 Hz, 2H), 7.47 (dd, J = 8.0, 4.8 Hz, 2H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , ; MS (EI,70 ev): m/z = [M + ]. f) General procedure for the synthesis of 1-m: To a round-bottom flask was added 2-chloropyrimidine (2.0 mmol), arylboronic acid (2 equiv), PdCl 2 (PPh 3 ) 2 (2.0 mol %) and Na 2 CO 3 (2M, 5 ml) in dioxane (5 ml). The reaction mixture was heated to 90 o C until the 2-chloropyrimidine was consumed completely (monitored by TLC). The heterogeneous aqueous was concentrated under reduced pressure and the residue was diluted with EtOAc (30 ml), washed by H 2 O (30 ml) and brine (30 ml). The organic layer was dried over Na 2 SO 4, concentrated and purified by column chromatography on silica gel (eluant: PE / EtOAc) to afford 1-m. [3] 2-phenylpyrimidine (1-m) [3] : 1 H NMR (400 MHz, CDCl 3 ) δ 8.76 (d, J = 4.8 Hz, 2H), (m, 2H), (m, 3H), 7.11 (t, J = 4.8 Hz, 1H); 13 C NMR (100 MHz, CDCl 3 ) δ , , , , , , ; MS (EI,70 ev): m/z = [M + ]. 5

6 g) General procedure for the synthesis of 1t: The mixture of CuBr (2.9 mg, 0.02 mmol), pyridine (4.8 mg, 0.06 mmol), aniline (93 mg, 1 mmol) and 2-methoxybenzenamine (0.2 mmol) in toluene (4 ml) was vigorously stirred at 60 C under O 2 (1 atm) for 24 h. Then cooling down to room temperature and concentrating in vacuum, the residue was purified by flash chromatography on silica gel (eluent: petroleum ether/ethyl acetate = 200:1) to afford 1t. [1] (E)-1-(2-methoxyphenyl)-2-phenyldiazene (1t) [4] : 1 H NMR (400 MHz, CDCl 3 ) δ 7.90 (dt, J = 3.7, 2.1 Hz, 2H), 7.66 (dd, J = 8.0, 1.6 Hz, 1H), (m, 4H), 7.09 (t, J = 7.0 Hz, 1H), (m, 1H), 4.01 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ , , , , , , , , , , 56.39; MS (EI, 70 ev): m/z = [M + ]. h) General procedure for the synthesis of 4: A 10 ml of reaction tube was charged with (E)-1-(2-methoxyphenyl)-2-phenyldiazene (1t, 0.3 mmol), 4-methylbenzonitrile (2p, 10.8 mmol), Pd(OAc) 2 (10 mol %), TBHP (3.6 mmol) and trifluorotoluene (2.0 ml) under Ar atmosphere. After the reaction was carried out at 80 o C for 72 h, it was cooled to room temperature and concentrated in vacuum. The residue was purified by flash chromatography (silica gel, ethyl acetate/petroleum ether 1:10, v/v), affording the desired compound 3-2p, yield: 35%. Red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.72 (d, J = 8.5 Hz, 2H), (m, 1H), 7.53 (d, J = 8.5 Hz, 2H), (m, 2H), (m, 4H), 7.02 (dd, J = 7.5, 1.0 Hz, 1H), 4.09 (s, 3H); 13 C NMR (101 MHz, CDCl 3 ) δ , , , , , , , , , , , , , , , , 56.71; HR-MS (EI) calcd for [M +H] + : C 21 H 16 N 3 O , found ; IR (KBr, cm -1 ): 3069, 2931, 2847, 2361, 2230, 1673, 1575, 1466, 1411, 1284, 1074, 974, 851,762, 689,

7 The procedure for reductive intramolecular cyclization was similar as the reference [5] : A 5 ml of reaction tube was charged with zinc dust (26.0 mg, 0.40 mmol), NH 4 Cl (32.1 mg, 0.60 mmol), 3-2p (68.3 mg, 0.20 mmol) and CH 3 OH (0.50 ml). The reaction mixture was stirred at 40 o C for 30 min. After red color was completely disappeared, the resulting slurry was diluted with water and filtrated. The filter liquor was then extracted with EtOAc (3 5 ml), and dried over MgSO 4. Then the solvent was evaporated under reduced pressure and the residue was purified by flash chromatography (silica gel, ethyl acetate/petroleum ether 1:5, v/v), affording the desired product 4 (62.5 mg, 96%). White solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.66 (d, J = 8.5 Hz, 2H), 7.45 (d, J = 8.5 Hz, 2H), (m, 5H), 7.25 (d, J = 8.4 Hz, 1H), 7.12 (dd, J = 8.4, 7.4 Hz, 1H), 6.66 (d, J = 7.4 Hz, 1H), 4.06 (s, 3H); 13 C NMR (101 MHz, CDCl 3 ) δ , , , , , , , , , , , , , , , , 55.60; MS (ESI): m/z = [M + ]; IR (KBr, cm -1 ): 2925, 2855, 2360, 2225, 1603, 1550, 1498, 1456, 1421, 1361, General procedure for reaction condition screening General procedure for acylation of azobenzene: A 10 ml of reaction tube was charged with azobenzene (1a, 0.15 mmol), substituted toluene (2a, 5.4 mmol), Pd(OAc) 2 (10 mol%), TBHP (1.8 mmol) and trifluorotoluene (1.0 ml) under Ar atmosphere. After the reaction was carried out at 80 o C for 30 h, it was cooled to room temperature and concentrated in vacuum. The residue was purified by flash chromatography (silica gel, ethyl acetate/petroleum ether 1:30, v/v), affording the desired oxidatively coupled product. Table S1. Optimization of the Pd-catalyzed ortho-acylation of azobenzene with toluene a 7

8 entry PdX 2 (mol %) oxidant (equiv) solvent yield (%) b 1 PdCl 2 TBHP CH 3 NO PdCl 2 TBHP DCE 15 3 PdCl 2 TBHP DMSO trace 4 PdCl 2 TBHP dioxane trace 5 PdCl 2 TBHP PhCF PdCl 2 DDQ PhCF PdCl 2 MnO 2 PhCF PdCl 2 Na 2 S 2 O 8 PhCF PdCl 2 O 2 PhCF PdCl 2 (MeCN) 2 TBHP PhCF 3 trace 11 Pd(TFA) 2 TBHP PhCF 3 trace 12 Pd(OAc) 2 TBHP PhCF Pd(OAc) 2 TBHP PhCF 3 55 c,d 14 Pd(OAc) 2 TBHP PhCF 3 60 c,e 15 Pd(OAc) 2 TBHP PhCF 3 67 c,f 16 Pd(OAc) 2 TBHP PhCF 3 77 c,g 17 Pd(OAc) 2 TBHP PhCF 3 80 c,h 18 Pd(OAc) 2 TBHP 60 I, j a Unless otherwise noted, the reactions were carried out using azobenzene (1a) (0.15 mmol) and toluene (2a) (0.30 mmol) with palladium catalyst (10 mol %) in the presence of oxidant (4.0 equiv) in solvent (2.0 ml) at 110 C under Ar for 30 h in a sealed tube, followed by flash chromatography on SiO 2. b Isolated yield. c Reaction temperature: 80 o C. d 12.0 equiv of toluene and 12.0 equiv of TBHP were used. e 24.0 equiv of toluene and 12.0 equiv of TBHP were used. f 24.0 equiv of toluene and 24.0 equiv of TBHP were used. g 36.0 equiv of toluene and 12.0 equiv of TBHP were used. h 36.0 equiv of toluene and 24.0 equiv of TBHP were used. i 1.0 ml of PhCF 3 was not used. j 36.0 equiv of toluene was used. 4. The mechanism exploration of Pd-catalyzed ortho-acylation of azobenzene with toluene 4.1. The GC spectra about the oxidantion progress of toluene. 8

9 Scheme 1 A 10 ml of reaction tube was charged with toluene (2a, 5.4 mmol, 36 equiv.), Pd(OAc) 2 (0.015 mmol, 10 mol %), TBHP (1.8 mmol, 12 equiv.) and trifluorotoluene (2.0 ml) under Ar atmosphere. Then the mixture was stirred at 80 o C for 6 h, the corresponding reaction progress was monitored by GC-MS. The corresponding GC-MS spectra about the oxidation products of toluene was shown in Figure 1. Figure 1. The GC spectra from the reaction mixture which was carried out for 6 h. Figure 2. The GC-MS spectra of 2aa, FW of 2aa is As shown in Figure 1, the oxidantion product of toluene was benzaldehyde. Dacane comes from the TBHP solution (a solution of 5.5 M in decane) Pd(II)-catalyzed ortho-acylation of azobenzene with benzaldehyde. CHO N Ph Pd(OAc) 2 (10 mol %) N TBHP (12 equiv) PhCF H 3 (2 ml), 80 o C, 30 h 68% yield 1a (0.15 mmol) 2q (0.15 mmol) 3a Scheme 2 N N Ph A 10 ml of reaction tube was charged with azobenzene (1a, 0.15 mmol), benzaldehyde 2q (0.15 mmol, 1 equiv.), Pd(OAc) 2 (0.015 mmol, 10 mol %), TBHP (0.6 mmol, 12 equiv.) and trifluorotoluene (2.0 ml). After the mixture was stirred under Ar atmosphere at 80 o C for 30 h, cooled to room temperature and concentrated in vacuum. The residue was purified by flash chromatography (silica gel, ethyl acetate/petroleum ether 1:30, v/v) to afford the desired product 3a in 68 % yield. Ph O 4.3. Pd(II)-catalyzed ortho-acylation of azobenzene with toluene in the presence of TEMPO. 9

10 Scheme 3 A 10 ml of reaction tube was charged with azobenzene (1a, 0.15 mmol), toluene (2q, 5.4 mmol, 36 equiv.), Pd(OAc) 2 (0.015 mmol, 10 mol %), TBHP (1.8 mmol, 12 equiv.), TEMPO (0.15 mmol, 1 equiv.) and trifluorotoluene (2.0 ml). Then the mixture was stirred under Ar atmosphere at 80 o C for 30 h, the corresponding reaction progress was monitored by GC-MS, unfortunately, no product 3a was observed The GC spectra of oxidative process of toluene in the presence of TEMPO. Scheme 4 A 10 ml of reaction tube was charged with toluene (2q, 5.4 mmol, 36 equiv.), Pd(OAc) 2 (0.015 mmol, 10 mol %), TBHP (1.8 mmol, 12 equiv.), TEMPO (0.15 mmol, 1 equiv.) and trifluorotoluene (2.0 ml). Then the mixture was stirred under Ar atmosphere at 80 o C for 12 h, the reaction progress was monitored by GC-MS, and the corresponding GC-MS spectra indicated that TEMPO suppressed the formation of desired product 3a ( Figure 3). Figure 3. The GC spectra from the reaction mixture after 12 h. 10

11 Figure 4. The GC-MS spectra of 2aa, FW of 2aa is As shown in Figure 3, benzaldhydes coiuld be formed even in the presence of TEMPO, this results indicated that TEMPO suppressed the acylation instead of the oxidantion of toluene. 5. Characterization data of coupling products (E)-Phenyl(2-(phenyldiazenyl)phenyl)methanone (3-1a) [5] : red oil; 1 H NMR (400 MHz, CDCl 3 ) δ 7.94 (d, J = 7.9 Hz, 1H), 7.77 (d, J = 7.5 Hz, 2H), (m, 1H), 7.58 (d, J = 4.2 Hz, 2H), (m, 3H), 7.34 (m, 5H). 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , ; MS (EI,70 ev): m/z = [M + ]; IR (KBr, cm -1 ): 2923, 2852, 2361, 1787, 1754, 1664, 1595, 1455, 1390, 1232, 997, 930, 841, 741, 682, 531. (E)-(2-(phenyldiazenyl)phenyl)(p-tolyl)methanone (3-1b) [5] : red oil; 1 H NMR (400 MHz, CDCl 3 ) δ ppm 7.93 (d, J = 7.6 Hz, 1H), 7.67 (d, J = 8.0 Hz, 2H), (m, 1H),

12 (m, 2H), (m, 2H), (m, 3H), 7.17 (d, J = 8.0 Hz, 2H), 2.35 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , 21.66; MS (EI,70 ev): m/z = [M + ]; IR (KBr, cm -1 ): 3829, 3744, 2924, 2855, 1661, 1603, 1462, 1286, 1150, 1025, 929, 835, 770, 688, 539, 472. (E)-(2-(phenyldiazenyl)phenyl)(m-tolyl)methanone (3-1c) [5] : red oil; 1 H NMR (400 MHz, CDCl 3 ) δ 7.93 (d, J = 8.0 Hz, 1H), (m, 2H), (m, 2H), 7.52 (d, J = 7.5 Hz, 1H), 7.46 (m, 2H), (m, 3H), (m, 2H), 2.32 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , , 21.26; MS (EI,70 ev): m/z = [M + ]; IR (KBr, cm -1 ): 2361, 1665, 1592, 1272, 955, 759, 688. (E)-(2-(phenyldiazenyl)phenyl)(o-tolyl)methanone (3-1d) [5] : red oil; 1 H NMR (400 MHz, CDCl 3 ) δ 7.72 (dd, J = 7.9, 1.0 Hz, 1H), 7.61 (dd, J = 7.4, 1.5 Hz, 1H), 7.52 (m, 2H), (m, 5H), (m, 2H), 7.13 (d, J = 7.4 Hz, 1H), 6.99 (t, J = 7.2 Hz, 1H), 2.49 (s, 3H); NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , , 21.19; MS (EI,70 ev): m/z = [M + ]; IR (KBr, cm -1 ): 3064, 2923, 2850, 2738, 2323, 1961, 1815, 1664, 1589, 1453, 1379, 1297, 1245, 1153, 1026, 924, 766, 731, 688, 633, 541, C (E)-(3,5-dimethylphenyl)(2-(phenyldiazenyl)phenyl)methanone (3-1e): red oil; 1 H NMR (400 MHz, CDCl 3 ) δ 7.92 (d, J = 7.8 Hz, 1H), (m, 1H), (m, 2H), (m, 12

13 2H), (m, 5H), 7.12 (s, 1H), 2.27 (s, 6H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , ,119.69,21.14; HR-MS (EI) calcd for [M +H] + : C 21 H 18 N 2 O , found ; IR (KBr, cm -1 ): 3058, 2922, 2856, 1961, 1666, 1598, 1449, 1381, 1309, 1223, 1138, 1025, 966, 865, 770, 684, 645, 542, 477. (E)-(2-chlorophenyl)(2-(phenyldiazenyl)phenyl)methanone (3-1f) [5] : red oil. 1 H NMR (400 MHz, CDCl 3 ) δ ppm 7.82 (dd, J = 7.5, 1.3 Hz, 1H), 7.73 (dd, J = 7.9, 0.9 Hz, 1H), 7.65 (td, J = 7.6, 1.5 Hz, 1H), 7.59 (td, J = 7.4, 1.3 Hz, 1H), 7.53 (dd, J = 6.5, 1.7 Hz, 1H), (m, 3H), (m, 2H), (m, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , ; MS (EI, 70 ev): m/z = [M + ]; IR (KBr, cm -1 ): 3434, 2920, 2851, 2361, 2340, 1658, 1588, 1433, 1276, 1262, 1057, 928, 750, 685, 477. (E)-(4-chlorophenyl)(2-(phenyldiazenyl)phenyl)methanone (3-1g) [5] : red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.99 (dd, J = 8.0, 0.7 Hz, 1H), (m, 3H), (m, 2H), (m, 2H), (m, 5H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , ; MS (EI,70 ev): m/z = [M + ]; IR (KBr, cm -1 ): 3063, 2925, 2855, 1669, 1587, 1482, 1399, 1290, 1151, 1093, 1014, 929, 845, 771, 683, 532,

14 (E)-(3-chlorophenyl)(2-(phenyldiazenyl)phenyl)methanone (3-1h): red solid; m.p C 1 H NMR (400 MHz, CDCl 3 ) δ ppm 7.97 (dd, J = 8.0, 0.6 Hz, 1H), 7.78 (t, J = 1.7 Hz, 1H), (m, 1H), (m, 3H), (m, 3H), (m, 3H), 7.28 (m, 1H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , ; HR-MS (EI) calcd for [M+H] + : C 19 H 14 ClN 2 O , found ; IR (KBr, cm -1 ): 3491, 3064, 2925, 2855, 1671, 1573, 1467, 1425, 1293, 1249, 1153, 1077, 1024, 951, 770, 725, 685, 634, 542. (E)-(4-bromophenyl)(2-(phenyldiazenyl)phenyl)methanone (3-1i) [5] : red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.96 (dd, J = 8.0, 0.6 Hz, 1H), (m, 3H), 7.57 (m, 2H), (m, 4H), (m, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , ; MS (EI,70 ev): m/z = [M + ]; IR (KBr, cm -1 ): 2921, 1664, 1583, 1474, 1393, 1285, 1150, 1067, 1011, 929, 842, 766, 685, 582, 538, 473. (E)-(2-bromophenyl)(2-(phenyldiazenyl)phenyl)methanone (3-1j): red oil; 1 H NMR (400 MHz, CDCl 3 ) δ ppm 7.84 (d, J = 7.5 Hz, 1H), (m, 2H), (m, 2H), 7.46 (d, J = 7.6 Hz, 1H), 7.37 (m, 5H), 7.28 (t, J = 7.6 Hz, 1H), 7.19 (m, 1H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , ; HR-MS (EI) calcd for [M+H] + : C 19 H 14 BrN 2 O , found ; IR(KBr, cm -1 ): 3062, 2922, 2853, 1667, 1586, 1464, 1431, 1295, 1241, 1152, 1025, 927, 767, 684, 626, 543,

15 (E)-Naphthalen-2-yl(2-(phenyldiazenyl)phenyl)methanone (3-1k): red oil; 1 H NMR (400 MHz, CDCl 3 ) δ 8.15 (s, 1H), 7.99 (m, 2H), (m, 3H), (m, 1H), 7.62 (d, J = 3.7 Hz, 2H), 7.54 (t, J = 7.5 Hz, 1H), (m, 3H), (m, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , , , , , ; HR-MS (EI) calcd for [M+H] + : C 23 H 17 N 2 O , found ; IR (KBr, cm -1 ): 3058, 2924, 2854, 1662, 1593, 1464, 1356, 1291, 1228, 1150, 1113, 1020, 921, 862, 821, 767, 687, 539, 475. (E)-(4-methoxyphenyl)(2-(phenyldiazenyl)phenyl)methanone (3-1l) [5] : red oil; 1 H NMR (400 MHz, CDCl 3 ) δ (d, J = 7.6 Hz, 1H), (dd, J =6.8 Hz, J = 2.0 Hz, 1H), (m, 5H), (m, 3H), 6.85 (dd, J =6.8 Hz, J = 2.0 Hz, 2H), 3.81 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , 55.46; MS (EI,70 ev): m/z = 316.1[M + ]; IR (KBr, cm -1 ): 3062, 2926, 2848, 2361, 2051, 1963, 1659, 1598, 1506, 1460, 1254, 1174, 1149, 1107, 1027, 930, 845, 771, 689, 606, 541. (E)-4-(2-(phenyldiazenyl)benzoyl)benzonitrile (3-1m) [5] : red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ ppm (m, 1H), (m, 2H), (m, 1H), (m, 4H), (m, 5H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , 15

16 115.67; MS (EI,70 ev): m/z = 310.9[M + ]; IR (KBr, cm -1 ): 3853, 3739, 3619, 2922, 2361, 2229, 1671, 1516, 1391, 1280, 1146, 930, 853, 767, 683, 545. (E)-1-(4-(2-(phenyldiazenyl)benzoyl)phenyl)ethanone (3-1n): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.98 (d, J = 7.9 Hz, 1H), 7.92 (d, J = 8.4 Hz, 2H), 7.83 (d, J = 8.4 Hz, 2H), (m, 1H), 7.61 (m, 2H), 7.42 (d, J = 7.0 Hz, 2H), (m, 3H), 2.57 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , 26.85; HR-MS (EI) calcd for [M+H] + : C 21 H 17 N 2 O , found ; IR (KBr, cm -1 ): 2923, 2853, 1662, 1592, 1401, 1362, 1250, 1151, 1106, 1071, 1021, 928, 851, 766, 683, 585, 538, 472. (E)-Ethyl 4-(2-(phenyldiazenyl)benzoyl)benzoate (3-1o): red oil; 1 H NMR (400 MHz, CDCl 3 ) δ 8.03 (d, J = 8.5 Hz, 2H), 7.99 (d, J = 8.1 Hz, 1H), 7.81 (d, J = 8.5 Hz, 2H), (m, 1H), (m, 2H), (m, 2H), (m, 3H), 4.36 (q, J = 7.1 Hz, 2H), 1.38 (t, J = 7.1 Hz, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , 61.38, 14.25; HR-MS (EI) calcd for [M+H] + : C 22 H 19 N 2 O , found ; IR (KBr, cm -1 ): 3063, 2924, 2855, 1956, 1718, 1670, 1589, 1464, 1401, 1272, 1103, 1018, 930, 864, 768, 719, 683,

17 (E)-(4-nitrophenyl)(2-(phenyldiazenyl)phenyl)methanone (3-1p) [5] : red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 8.19 (d, J = 8.6 Hz, 2H), 8.02 (d, J = 8.0 Hz, 1H), 7.89 (d, J = 8.6 Hz, 2H), 7.73 (t, J = 7.5 Hz, 1H), (m, 2H), (m, 5H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , MS (EI, 70 ev): m/z= [M + ]; IR (KBr, cm -1 ): 3861, 3742, 3621, 2362, 1675, 1599, 1524, 1344, 1282, 1148, 932, 854, 771, 710, 686, 527. (E)-(3-nitrophenyl)(2-(phenyldiazenyl)phenyl)methanone (3-1q): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 8.57 (s, 1H), 8.29 (d, J = 8.1 Hz, 1H), 8.04 (dd, J = 14.9, 7.8 Hz, 2H), 7.73 (t, J = 7.5 Hz, 1H), (m, 3H), 7.37 (m, 5H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , ; HR-MS (EI) calcd for [M+H] + : C 19 H 14 N 3 O , found ; IR (KBr, cm -1 ): 3852, 3739, 3619, 2361, 1675, 1531, 1386, 1348, 1263, 971, 757, 682. Phenyl(2-(pyrimidin-2-yl)phenyl)methanone (3-1r): white solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 8.53 (d, J = 4.9 Hz, 2H), 8.36 (dd, J = 7.6, 1.1 Hz, 1H), 7.71 (dd, J = 5.2, 3.3 Hz, 2H), (m, 2H), 7.50 (dd, J = 7.5, 1.3 Hz, 1H), (m, 1H), (m, 2H), 6.96 (t, J = 4.9 Hz, 1H); 13 C NMR (100 MHz, CDCl 3 ) δ , , , , , , , , , , , , , ; HR-MS (EI) calcd for [M+H] + : C 17 H 13 N 2 O , found ; IR (KBr, cm -1 ): 2963, 1665, 1626, 1583, 1543, 825, 809, 689, 639, 615,

18 (E)-(5-methyl-2-(p-tolyldiazenyl)phenyl)(phenyl)methanone (3-2a) [5] : red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.85 (d, J = 8.2 Hz, 1H), (m, 2H), (m, 2H), (m, 5H), 7.10 (d, J = 8.1 Hz, 2H), 2.47 (s, 3H), 2.32 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , 29.72, 21.45; MS (EI,70 ev): m/z = [M + ]; IR (KBr, cm -1 ): 3743, 3453, 2921, 2853, 2361, 1663, 1593, 1448, 1278, 1208, 1146, 961, 827, 744, 699, 644, 545. (E)-(4-methyl-2-(m-tolyldiazenyl)phenyl)(phenyl)methanone (3-2b): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.76 (d, J = 7.6 Hz, 2H), 7.71 (s, 1H), 7.52 (d, J = 7.7 Hz, 1H), 7.46 (t, J = 7.3 Hz, 1H), 7.37 (m, 3H), 7.21 (m, 3H), 7.10 (s, 1H), 2.51 (s, 3H), 2.28 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , , 21.49, 21.16; HR-MS (EI) calcd for [M+H] + : C 21 H 19 N 2 O , found ; IR (KBr, cm -1 ): 3839, 3712, 3615, 2923, 2854, 1667, 1599, 1378, 1285, 1261, 1178, 922, 826, 703, 612, 517. (E)-(3-methyl-2-(o-tolyldiazenyl)phenyl)(phenyl)methanone (3-2c): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.65 (d, J = 7.6 Hz, 2H), 7.48 (d, J = 7.4 Hz, 1H), (m, 2H), (m, 5H), 7.15 (d, J = 7.5 Hz, 1H), 7.07 (t, J = 7.6 Hz, 1H), 2.76 (s, 3H), 2.27 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , , 18.44, 17.28; HR-MS (EI) calcd for [M+H] + : C 21 H 19 N 2 O , found ; IR (KBr, cm -1 ): 3846, 3727, 3434, 2361, 2340, 1641, 1384, 1262, 1099, 749, 670,

19 (E)-(5-chloro-2-((4-chlorophenyl)diazenyl)phenyl)(phenyl)methanone (3-2d) [5] : red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.89 (d, J = 8.6 Hz, 1H), 7.75 (d, J = 7.7 Hz, 2H), (m, 2H), 7.51 (t, J = 7.3 Hz, 1H), 7.38 (m, 4H), 7.29 (d, J = 8.7 Hz, 2H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , ,124.17,121.12; MS (EI,70 ev): m/z = [M + ]; IR (KBr, cm -1 ): 3744, 2926, 1733, 1585, 1451, 1399, 1266, 1155, 1087, 1025, 955, 839, 753, 700, 648. (E)-(5-bromo-2-((4-bromophenyl)diazenyl)phenyl)(phenyl)methanone (3-2e): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.82 (d, J = 8.5 Hz, 1H), (m, 4H), 7.48 (m, 3H), 7.39 (t, J = 7.6 Hz, 2H), 7.28 (d, J = 8.6 Hz, 2H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , ; HR-MS (EI) calcd for [M+H] + : C 19 H 13 Br 2 N 2 O , found ; IR (KBr, cm -1 ): 3433, 2361, 2340, 1660, 1276, 1261, 750, 483. (E)-(5-fluoro-2-((4-fluorophenyl)diazenyl)phenyl)(phenyl)methanone (3-2f): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ ppm 7.97 (dd, J = 8.9, 5.1 Hz, 1H), (m, 2H), 7.51 (dd, J = 10.5, 4.3 Hz, 1H), (m, 4H), (m, 3H), 7.00 (t, J = 8.6 Hz, 2H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , (d, J C F = 65.4 Hz), (d, J C F = 67.1 Hz), , , (d, J C F = 7.1 Hz), , , , , (d, J C F = 9.0 Hz), (d, J C F = 8.7 Hz), (d, J C F = 22.8 Hz), (d, J C F = 19.3 Hz), (d, J C F = 20.6 Hz); HR-MS (EI) calcd for [M+H] + : C 19 H 13 F 2 N 2 O , found ; IR (KBr, cm -1 ): 3072, 2924, 1731, 1656, 1592, 1491, 1409, 1310, 1274, 1227, 1129, 1084, 844, 749, 702, 638,

20 (E)-(5-methoxy-2-((4-methoxyphenyl)diazenyl)phenyl)(phenyl)methanone (3-2g) [5] : red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ ppm 7.93 (d, J = 8.9 Hz, 1H), (m, 2H), 7.46 (t, J = 7.1 Hz, 1H), 7.36 (dd, J = 9.3, 6.1 Hz, 4H), 7.13 (dd, J = 8.9, 2.8 Hz, 1H), 7.03 (d, J = 2.7 Hz, 1H), (m, 2H), 3.91 (s, 3H), 3.80 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , 55.80, 55.48; MS (EI, 70 EV): m/z = [M + ]; IR (KBr, cm -1 ): 3749, 3736, 3615, 3589, 2922, 2851, 2363, 1668, 1651, 1595, 1574, 1521, 1284, 1254, 1234, 1102, 961, 749, 696, 516. (E)-Ethyl 3-benzoyl-4-((4-(ethoxycarbonyl)phenyl)diazenyl)benzoate (3-2h): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ (m, 2H), 8.00 (m, 3H), 7.77 (d, J = 7.3 Hz, 2H), 7.50 (m, 3H), 7.40 (t, J = 7.7 Hz, 2H), 4.44 (q, J = 7.1 Hz, 2H), 4.38 (q, J = 7.1 Hz, 2H), 1.41 (m, 6H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , , 61.68, 61.35, 14.30, 14.28; HR-MS (EI) calcd for [M+H] + : C 25 H 23 N 2 O , found ; IR (KBr, cm -1 ): 2923, 2852, 1720, 1669, 1589, 1450, 1403, 1365, 1244, 1148, 1097, 1016, 857, 766, 688, 636. (E)-(5-methoxy-2-(phenyldiazenyl)phenyl)(phenyl)methanone (3-2i): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.97 (d, J = 8.9 Hz, 1H), 7.79 (d, J = 7.5 Hz, 2H), 7.48 (t, J = 7.3 Hz, 1H), (m, 4H), (m, 3H), 7.15 (dd, J = 8.9, 2.6 Hz, 1H), 7.05 (d, J = 2.6 Hz, 1H), 3.92 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , 20

21 138.88, , , , , , , , , , , 55.84; HR-MS (EI) calcd for [M+H] + : C 20 H 17 N 2 O , found ; IR (KBr, cm -1 ): 3736, 3060, 2923, 2849, 1663, 1592, 1476, 1292, 1240, 1099, 1031, 960, 892, 850, 815, 770, 692, 629, 553, 521. (E)-(2-((4-methoxyphenyl)diazenyl)phenyl)(phenyl)methanone (3-2j): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.91 (d, J = 8.0 Hz, 1H), 7.76 (d, J = 7.5 Hz, 2H), (m, 1H), (m, 2H), 7.45 (m, 3H), 7.35 (t, J = 7.6 Hz, 2H), 6.81 (d, J = 8.9 Hz, 2H), 3.81 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , 55.52; HR-MS (EI) calcd for [M+H] + : C 20 H 17 N 2 O , found ; IR (KBr, cm -1 ): 3735, 3434, 3062, 2922, 2849, 2361, 2340, 1735, 1598, 1501, 1252, 1142, 1026, 929, 837, 764, 698, 632, 548. (E)-(5-methoxy-2-(p-tolyldiazenyl)phenyl)(phenyl)methanone (3-2k): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.95 (d, J = 8.9 Hz, 1H), 7.78 (d, J = 7.6 Hz, 2H), 7.47 (t, J = 7.4 Hz, 1H), 7.36 (t, J = 7.6 Hz, 2H), 7.28 (d, J = 8.2 Hz, 2H), 7.14 (dd, J = 8.9, 2.7 Hz, 1H), 7.09 (d, J = 8.2 Hz, 2H), 7.04 (d, J = 2.7 Hz, 1H), 3.91 (s, 3H), 2.32 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , 55.82, 21.40; HR-MS (EI) calcd for [M+H] + : C 21 H 19 N 2 O , found ; IR (KBr, cm -1 ): 3840, 3736, 3651, 3434, 2922, 2852, 2361, 2339, 1666, 1595, 1483, 1449, 1315, 1234, 1102, 1030, 963, 828, 750, 700, 553,

22 (E)-(2-((4-methoxyphenyl)diazenyl)-5-methylphenyl)(Phenyl)methanone (3-2l): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.83 (d, J = 8.2 Hz, 1H), 7.76 (d, J = 7.5 Hz, 2H), (m, 4H), 7.35 (t, J = 7.4 Hz, 3H), 6.80 (d, J = 8.7 Hz, 2H), 3.80 (s, 3H), 2.47 (s, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , 55.50, 21.40; HR-MS (EI) calcd for [M+H] + : C 21 H 19 N 2 O , found ; IR (KBr, cm -1 ): 3733, 3433, 2919, 2849, 2361, 2339, 1659, 1596, 1499, 1444, 1385, 1313, 1250, 1209, 1176, 1140, 1102, 1024, 961, 836, 695, 670, 646, 501. (E)-Ethyl 4-((2-benzoylphenyl)diazenyl)benzoate (3-2m): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ ppm 8.00 (d, J = 8.6 Hz, 2H), 7.96 (d, J = 7.4 Hz, 1H), (m, 2H), (m, 3H), 7.49 (t, J = 7.4 Hz, 1H), 7.44 (d, J = 8.6 Hz, 2H), 7.38 (t, J = 7.6 Hz, 2H), 4.37 (q, J = 7.1 Hz, 2H), 1.39 (t, J = 7.1 Hz, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , 61.27, 14.30; HR-MS (EI) calcd for [M+H] + : C 22 H 19 N 2 O , found ; IR (KBr, cm -1 ): 3741, 2926, 2362, 1708, 1647, 1290, 1271, 1126, 1106, 755, 677. (E)-Ethyl 3-benzoyl-4-(phenyldiazenyl)benzoate (3-2n): red solid; m.p C; 1 H NMR (400 MHz, CDCl 3 ) δ 8.31 (dd, J = 8.4, 1.8 Hz, 1H), 8.26 (d, J = 1.7 Hz, 1H), 7.99 (t, J = 9.0 Hz, 1H), (m, 2H), 7.49 (m, 3H), (m, 5H), 4.43 (q, J = 7.1 Hz, 2H), 1.42 (t, J = 7.1 Hz, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ ppm , , , , , , , , , , , , , , , , 61.58, 14.31; HR-MS (EI) calcd for [M+H] + : C 22 H 19 N 2 O , found ; IR (KBr, cm -1 ): 3750, 3434, 2921, 2851, 1715, 1664, 1272, 1101, 928, 861, 752, 698, 631, References [1] C. Zhang and N. Jiao, Angew. Chem. Int. Ed. 2010, 49, [2] S. Thies, H. Sell, C. Schutt, C. Bornholdt, C. Nather, F. Tuczek and R. Herges, J. Am. Chem. Soc. 2011, 133,

23 [3] X. J. Zheng, B. R. Song and B. Xu, Eur. J. Org. Chem. 2010, [4] R. Zhao, C. Y. Tan, Y. H. Xie, C. M. Gao, H. X. Liu and Y. Y. Jiang, Tetrahedron Lett. 2011, 52, [5] H. -J. Li, P. -H. Li and L. Wang, Org. Lett. 2013, 15,

24 7. 1 H and 13 C NMR spectra of the products 24

25 25

26 26

27 27

28 28

29 29

30 30

31 31

32 32

33 33

34 34

35 35

36 36

37 37

38 38

39 39

40 40

41 41

42 42

43 43

44 44

45 45

46 46

47 47

48 48

49 49

50 50

51 51

52 52

53 53

54 54

55 55

56 56

57 57