[(NHC)Au I ]-Catalyzed Acid Free Hydration of Alkynes at Part-Per-Million Catalyst Loadings

Transcription

1 SUPPORTING INFORMATION [(NHC)Au I ]-Catalyzed Acid Free Hydration of Alkynes at Part-Per-Million Catalyst Loadings Nicolas Marion, Rubén S. Ramón, and Steven P. Nolan Institute of Chemical Research of Catalonia (ICIQ) Av. Països Catalans 16, Tarragona (Spain) snolan@iciq.es General Information...S2 General Procedure for Optimization Reactions...S3 Hydration of Diphenylacetylene in Methanol...S4 General Procedures for Hydration Reactions...S6 Large Scale Hydration Reaction of 4-Octyne...S7 References...S7 S1

2 General Information All reagents were used as purchased. Dry solvents were purified by passing through a purification column from Innovative Technology Inc. (SPS-400-6). Silver salts were stored in the dark,wrapped in aluminum foil. [(NHC)AuCl] complexes were synthesized according to literature procedures. 1 1 H and 13 C Nuclear Magnetic Resonance (NMR) spectra were recorded on a Bruker- 400 MHz spectrometer at ambient temperature in CDCl 3 containing tetramethylsilane (TMS). Alkynes 1 were purchased from Aldrich or Alfa Aesar and used as received. Ketones 2 are commercially available (CAS #: 2a, [ ]; 2b, [ ]; 2c, [ ]; 2d, [ ]; 2e, [ ]; 2f, [ ]; 2g, [ ]; 2h, [ ]; 2i, [ ]; 2j, [ ]; 2k a, [ ]; 2k b, [ ]; 2l a, [ ]; 2l b, [ ]) and their spectroscopic data were found in good agreement with previously reported characterization data. S2

3 General Procedures for Optimization Studies Gold catalyst optimization In a sealed 4 ml reaction vial equipped with a magnetic stirring bar, the catalyst (2 mol %) was added to 1,4-dioxane (1 ml). A small amount of AgSbF 6 (covering the tip of a spatula) was added and the reaction mixture was stirred for 1 minute. Diphenylacetylene (100 mg, 561 µmol, 1 equiv) was added, followed by distilled H 2 O (100 µl). The reaction mixture was then heated at 80ºC for the indicated time. Conversions were monitored by GC. Silver salt optimization In a sealed 4 ml reaction vial equipped with a magnetic stirring bar, [(IPr)AuCl] (7.0 mg, 11 µmol, 2 mol %) was added to 1,4-dioxane (1 ml). A small amount of silver salt minute. Diphenylacetylene (100 mg, 561 µmol, 1 equiv) was added, followed by distilled H 2 O (100 µl). The reaction mixture was then heated at 80ºC for the indicated time. Conversions were monitored by GC. Water amount optimization In a sealed 4 ml reaction vial equipped with a magnetic stirring bar, [(IPr)AuCl] (3.5 mg, 5.61 µmol, 2 mol %) was added to 1,4-dioxane (3 ml). A small amount of AgSbF 6 minute. Diphenylacetylene (50 mg, 281 µmol, 1 equiv) was added, followed by a defined amount of distilled H 2 O. The reaction mixture was then heated for 2 h at 80ºC. Conversions were monitored by GC. Solvent optimization In a sealed 4 ml reaction vial equipped with a magnetic stirring bar, [(IPr)AuCl] (7.0 mg, 11 µmol, 2 mol %) was added to the solvent (1 ml). A small amount of AgSbF 6 minute. Diphenylacetylene (100 mg, 561 µmol, 1 equiv) was added, followed by distilled S3

4 H 2 O (100 µl). The reaction mixture was then heated at 80ºC for the indicated time. Conversions were monitored by GC. Hydration of Diphenylacetylene in Methanol Procedure In a sealed 4 ml reaction vial equipped with a magnetic stirring bar, [(IPr)AuCl] (7.0 mg, 11 µmol, 2 mol %) was added to MeOH (2 ml). A small amount of AgSbF 6 (covering the tip of a spatula) was added and the reaction mixture was stirred for 1 minute. Diphenylacetylene 1a (100 mg, 561 µmol, 1 equiv) was added, followed by addition of distilled H 2 O (1 ml). The reaction mixture was heated at 65ºC. Conversions were monitored by GC. Reported yields are average of two runs. GC Analysis 1a [(IPr)AuCl]/AgSbF 6 (2 mol %) MeOH/H 2 O (2:1) 65 C O 2a OMe Diphenylacetylene 1a Benzylphenylketone 2a Methyl-enolether 3 70 Percentage (%) Time (h) S4

5 Isolation of 3 and its conversion into 2a 1a [(IPr)AuCl]/AgSbF 6 (2 mol %) anhydrous MeOH 80 C OMe [(IPr)AuCl]/AgSbF 6 (2 mol %) MeOH/H 2 O (2:1) 3, 80% 80 C (E:Z, 10/90) O 2a, quant. Isolation of 3 In a 25 ml Schlenk tube equipped with a magnetic stirring bar, anhydrous MeOH (4 ml) was added to [(IPr)AuCl] (14 mg, 22 µmol, 2 mol %) under inert atmosphere. A small amount of AgSbF 6 (covering the tip of a spatula) was added and the reaction mixture was stirred for 1 minute. Diphenylacetylene (178 mg, 1 mmol, 1 equiv) was added and the reaction mixture was then heated overnight at 65ºC. Volatile components were then removed under reduced pressure and the residue was dissolved in DCM. The solution was filtered over a plug of silica (~1 cm, DCM) and the solvent removed under reduced pressure, affording 169 mg (804 µmol, E/Z 1:9, 80%) of compound 3. Conversion of 3 into 2a In a sealed 4 ml reaction vial equipped with a magnetic stirring bar the [(IPr)AuCl] (7.0 mg, 11 µmol, 2 mol %) was added to MeOH (2 ml). A small amount of AgSbF 6 minute. 3 (100 mg, 476 µmol, 1 equiv) was then added, followed by addition of distilled H 2 O (1 ml). The reaction mixture was heated for 6 days at 80ºC. Full conversion into ketone 2a was observed by GC. S5

6 General Procedures for Hydration Reactions General Procedure at 1000 ppm catalyst loadings In a sealed 4 ml reaction vial equipped with a magnetic stirring bar, [(IPr)AuCl] (62 µl of a 10 mg/ml solution in THF, 1 µmol, 1000 ppm) was added to 1,4-dioxane (660 µl). Then, the tip of a spatula of AgSbF 6 was added and the reaction mixture was stirred for 1 minute. Alkyne 1 (1 mmol, 1 equiv) was added, followed by addition of distilled H 2 O (330 µl). The reaction mixture was heated for 18 h at 120ºC and then allowed to cool to room temperature. 1 H NMR yields were determined by adding a known amount of benzaldehyde, as internal standard, to the crude product. Reported yields are average of two runs. General Procedure at 100 ppm catalyst loadings In a sealed 4 ml reaction vial equipped with a magnetic stirring bar [(IPr)AuCl] (62 µl of a 1 mg/ml solution in THF, 0.1 µmol, 100 ppm) was added to 1,4-dioxane (660 µl). Then, the tip of a spatula of AgSbF 6 was added and the reaction mixture was stirred for 1 minute. Alkyne 1 (1 mmol, 1 equiv) was added, followed by addition of distilled H 2 O (330 µl). The reaction mixture was heated for 18 h at 120 ºC and then allowed to cool to room temperature. 1 H NMR yields were determined by adding a known amount of benzaldehyde, as internal standard, to the crude product. Reported yields are average of two runs. General Procedure at 10 ppm catalyst loadings In a sealed 50 ml reaction vial equipped with a magnetic stirring bar, [(IPr)AuCl] (62 µl of an 1 mg/ml solution in THF, 0.1 µmol, 10 ppm) was added to 1,4-dioxane (6.6 ml). Then, the tip of a spatula of AgSbF 6 was added and the reaction mixture was stirred for 1 minute. Alkyne 1 (10 mmol, 1 equiv) was added, followed by addition of distilled H 2 O (3.3 ml). The reaction mixture was heated for 72 h at 120 ºC and then allowed to cool to room temperature. 1 H NMR yields were determined by adding a known amount of benzaldehyde, as internal standard, to the crude product. Reported yields are the average of two runs. S6

7 Large Scale Hydration Reaction of 4-Octyne Procedure In a sealed 50 ml reaction vial equipped with a magnetic stirring bar, [(IPr)AuCl] (1.0 mg, 2 µmol, 100 ppm) was added to 1,4-dioxane (13 ml). AgSbF 6 (0.7 mg, 2 µmol, 100 ppm) was added and the solution was stirred for 1 minute. 4-Octyne 1i (20 mmol, 2.20 g, 1 equiv) was added, followed by addition of distilled H 2 O (6.6 ml). The reaction mixture was then heated for 18 h at 120ºC. Volatile components were then removed under reduced pressure and the residue dissolved in DCM. The solution was filtered over a plug of silica (~1 cm) and the solvent was removed under reduced pressure, affording 2.15 g (16.8 mmol, 84%) of ketone 2i. References (1) de Frémont, P.; Scott, N. M.; Stevens, E. D.; Nolan, S. P. Organometallics 2005, 24, S7