methyl 5,5-dimethoxypentanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Methyl 5,5-dimethoxyvalerate (20.0 g, 0.114 mol), propane-1,3-diol (13 g, 0.17 mol) and para-toluene sulphonic acid (2.17 g, 0.0114 mol) were heated under Dean-Stark conditions in toluene (100 ml) for 4 h. The mixture was cooled to room temperature and diluted with diethyl ether (100 ml) and then neutralized with solid sodium bicarbonate. The solid was filtered and the filtrate evaporated to give a pale yellow oil (22.3 g). A 10 g portion of this was then purified by silica gel chromatography (eluent 30% EtOAc:hexane) which gave the title compound as a colourless oil (6.82 g). The solid was filtered the filtrate evaporated

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Methyl 5,5-dimethoxyvalerate (20.0 g, 0.114 mol), propane-1,3-diol (13 g, 0.17 mol) and para-toluene sulphonic acid (2.17 g, 0.0114 mol) were heated under Dean-Stark conditions in toluene (100 ml) for 4 h. The mixture was cooled to room temperature and diluted with diethyl ether (100 ml) and then neutralized with solid sodium bicarbonate. The solid was filtered and the filtrate evaporated to give a pale yellow oil (22.3 g). A 10 g portion of this was then purified by silica gel chromatography (eluent 30% EtOAc:hexane) which gave the title compound as a colourless oil (6.82 g). The solid was filtered the filtrate evaporated

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Methyl 5,5-dimethoxyvalerate (20.0 g, 0.114 mol), propane-1,3-diol (13 g, 0.17 mol) and para-toluene sulphonic acid (2.17 g, 0.0114 mol) were heated under Dean-Stark conditions in toluene (100 ml) for 4 h. The mixture was cooled to room temperature and diluted with diethyl ether (100 ml) and then neutralized with solid sodium bicarbonate. The solid was filtered and the filtrate evaporated to give a pale yellow oil (22.3 g). A 10 g portion of this was then purified by silica gel chromatography (eluent 30% EtOAc:hexane) which gave the title compound as a colourless oil (6.82 g). The solid was filtered the filtrate evaporated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 12 mmoles methyl 5,5-dimethoxypentanoate (Stevens, R. V. et al., J Am Chem Soc (1979) 7054) were dissolved in 20 ml 50% aqueous methanol. 16 mmoles NaOH were added and the mixture was stirred for 2 hr at room temperature. The solvent was then evaporated, the residue layered with 30 ml EtOAc, and the sodium salt neutralized with ice-cold 1N HCl. The aqueous phase was extracted with an additional 20 ml EtOAc, the organic extracts combined and dried over K2CO3. The product was filtered and the solvent evaporated to provide 5,5-dimethoxypentanoic acid. The solvent was then evaporated The aqueous phase was extracted with an additional 20 ml EtOAc dried over K2CO3 The product was filtered the solvent evaporated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a suspension of LAH (0.4 g, 11 mmol) in tetrahydrofuran (20 ml) was added dropwise at 0° C. methyl 5,5-dimethoxyvalerate (3.5 g, 20 mmol) dissolved in tetrahydrofuran (30 ml), which was then stirred for 2 hours. After the reaction was completed, the mixture was poured into ice-water (50 ml) and then extracted with ether. The organic layer was dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to give a crude product. This crude product thus obtained was subjected to silica gel column chromatography (n-hexane:ethyl acetate-2:1) to give 5,5-dimethoxypentanol (1.02 g, yield 34%). Methanesulfonylchloride (3.2 g, 28 mmol) and triethylamine (3.0 g, 30 mmol) dissolved in dichloromethane (50 ml) were added thereto, and the mixture was stirred at room temperature for 1 hour. After the reaction was completed, the reaction mixture was poured into water and extracted with chloroform. The organic layer was dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to give a crude product (2.36 g). While, 4,4,5,5,5-pentafluoropentyl thioacetate (5.7 g, 24 mmol) prepared in Step 1 was dissolved in methanol (10 ml), sodium methoxide (23 mg, 23 mmol, 11.0 mol/l) was added thereto, and the resulting mixture was stirred at room temperature for 1 hour. To this solution was added dropwise the crude product prepared above (0.90 g) dissolved in tetrahydrofuran (10 ml), which was then stirred at room temperature for 5 hours. After the reaction was completed, the reaction mixture was poured into water and extracted with ether. The organic layer was dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to give a crude product. This crude product thus obtained was subjected to silica gel column chromatography (n-hexane:ethyl acetate=20:1) to give 5,5-dimethoxy-1-(4,4,5,5,5-pentafluoropentylthio)pentane (460 mg). extracted with ether The organic layer was dried over anhydrous magnesium sulfate concentrated under reduced pressure to give a crude product This crude product thus obtained