87184-80-3

83067-20-3

87184-80-3

5) Preparation of 5-(tert-butyldimethylsilyloxy)pentanal: To a solution of 5-(tert-butyldimethylsilyloxy)-1-pentanol (16.8 mmol, 3.66 g) in dichloromethane (30 mL) was added sequentially water (5.6 mL), potassium bromide (1.7 mmol, 202 mg), tetrabutylammonium hydrogensulfate (0.84 mmol, 290 mg), and TEMPO (30 mg). The resulting light brown solution was cooled to 5°C and sodium hypochlorite solution (19.3 mmol, 30 mL, 5%) was added slowly and dropwise at this temperature. When half of the sodium hypochlorite solution was added, solid potassium carbonate (300 mg) was added to maintain the basicity of the reaction mixture. Subsequently, the addition of the remaining sodium hypochlorite solution was continued dropwise at 5-10 °C. At this point, a precipitate appeared in the reaction mixture and stirring was continued at 10-15 °C for 1 hour. Upon completion of the reaction, water (100 mL) was added to dilute it. The mixture was extracted with ether (2 x 100 mL), the organic phases were combined, washed with brine (150 mL) and the organic layer was dried with anhydrous magnesium sulfate. The desiccant was removed by filtration and the solvent was concentrated under reduced pressure to give 5-(tert-butyldimethylsilyloxy)pentanal (3.32 g, 91% yield) as a light brown oil.ES(+)-HRMS m/z calculated value C11H24O2Si [M+H]+ 217.1619, measured value 217.1619.