Aqueous DMF 538,539 and sulfolane 541 have been preferred. 2,153 Solvent choice has a dramatic effect on the rate. For fine organic synthesis, the most useful appear to be copper(II) chloride, 537–539 hydroquinone 537,540 and t-butyl hydroperoxide. The choice of oxidant must be tailored to the reaction. Other reoxidants include benzoquinone, potassium peroxydisulfate, sodium dichromate, nitric acid and t-butyl hydroperoxide. When used in conjunction with oxygen, even the copper salt is utilized catalytically. Copper(II) chloride is by far the most common oxidant. The formation of Pd(0) requires an oxidant to make the reaction catalytic. Purification by flash column chromatography (10:1, dichloromethane/acetone + 1% triethylamine) affords phenyl-3- O-methyl-4,6- O-benzylidene-1-seleno-β- d-glucopyranoside as a colourless oil (0.15 g, 75%). Separate the organic layer and extract the aqueous phase with ethyl acetate (5 × 5 ml), dry the combined organic layers (MgSO 4) and remove solvents in vacuo to furnish the crude product as a pale yellow oil. Allow the reaction vessel to cool to room temperature and pour into a separatory funnel containing distilled water (3 ml) and 50% aqueous ammonia solution (3 ml) to afford a dark blue solution. Add methyl iodide (0.16 ml, 2.50 mmol) and heat the reaction mixture at reflux for 24 h. Add anhydrous copper(II) chloride (67.0 mg, 0.50 mmol) whereupon the white slurry will immediately dissolve to form a dark green solution. Stir the reaction mixture for 1 h at room temperature during this time a thick white slurry will form and hydrogen will be evolved. Stafford, in Carbohydrates, 2003 Procedure.īefore the protection reaction is commenced, the copper(II) chloride must be dried under reduced pressure (high vacuum, ∼ 0.1 mm Hg) at 80 ☌ for 24 h.Īdd sodium hydride (0.04 g, 1.00 mmol, 60% dispersion in oil) portion-wise to a stirred solution of phenyl-4,6- O-benzylidene-1-seleno-β- d-glucopyranoside (0.20 g, 0.50 mmol) in anhydrous THF (10 ml).
Kugelrohr distillation (95–100☌) of this crude reaction mixture under nitrogen provided chlorodiethylsilane (32.2 g, 77%). The diethyl ether was distilled, and the reaction mixture was transferred to a 100 mL flame-dried round-bottomed flask via a syringe, carefully leaving behind any remaining copper salt. After 43 h, the reaction mixture was filtered under a nitrogen atmosphere, and the flask was rinsed with diethyl ether (2 × 50 mL). After 4 h, it was noted that the reaction turned from orange brown to light gray in color with the formation of a black precipitate. Upon cooling to room temperature, copper(I) iodide (3.24 g, 17.0 mmol), diethyl ether (680 mL), and diethylsilane (30.0 g, 340 mmol) were successively added, and the resulting slurry was stirred at room temperature for 43 h. Kyushin, in Efficient Methods for Preparing Silicon Compounds, 2016 Experimental procedureĪnhydrous copper(II) chloride (96.5 g, 714 mmol) was dried under vacuum at 200☌ in a 2-L two-necked round-bottomed flask for 12 h with stirring.