4,4-dimethyloxane-2,6-dione

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:

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: A solution of 3,3-dimethylglutaric anhydride in dry THF (60 cm3) was added over 30 min. to lithium aluminum hydride in dry THF (300 cm3) under nitrogen at 0° C. The mixture was then brought gradually up-to reflux. After 3 h, the mixture was cooled, treated with water (3.3 cm3), sodium hydroxide solution (15%, 3.3 cm3) and water (9.9 cm3). The mixture was then filtered, the precipitate extracted with EtOAc (×3), and the combined organics evaporated to afford 3,3-dimethyl-1,5-pentanediol (quantitative yield); 1H NMR (CDCl3) δ 0.95 (s, 6H), 1.57 (t, 4H, J=6.3 Hz), 3.75 (t, 4H, J−6.3 Hz). The mixture was then brought gradually up-to reflux the mixture was cooled The mixture was then filtered the precipitate extracted with EtOAc (×3) the combined organics evaporated

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

Procedure: 3,3-Dimethylglutaric anhydride (5.0 g.) and benzyl alcohol (11 ml.) were heated together at 150° C. for 16 hours. The cooled reaction mixture was partitioned between saturated sodium carbonate solution (50 ml.) and ether (50 ml.). The aqueous layer was separated, acidified with 2M hydrochloric acid and extracted with ether. The extracts were evaporated. The residual yellow oil (4.6 g.) was purified by chromatography on silica gel with methylene chloride as eluant to give benzyl hydrogen 3,3-dimethylglutarate as an oil (1.5 g.); NMR (CDCl3): 1.1 (6H,s, CH3), 2.45+2.47 (4H, 2s, COCH2), 5.12 (2H,s, OCH2), 7.37 (5H, s, aromatic H), 8.45 (1H, br.s, CO2H)ppm. This benzyl ester (1.5 g.) was dissolved in methylene chloride (15 ml.) and stirred with thionyl chloride (2.2 ml.) and N,N-dimethylformamide (DMF) (0.3 ml.) for 3 hours. The solvent was evaporated and the residue was dissolved in dry toluene (15 ml.) and the solution re-evaporated. This was repeated twice to remove excess thionyl chloride. The residual oil (1.5 g.) containing crude benzyl 4-chloroformyl-3,3-dimethylbutyrate was dissolved in methylene chloride (25 ml.). The solution was added to a cooled solution of 1,3-dipalmitin (1.4 g.) in methylene chloride (25 ml.) containing pyridine (0.32 ml.). The mixture was stirred for 2 hours at 0°-5° C. and then for 46 hours at ambient temperature. The solvent was evaporated and the residue was partitioned between ether (70 ml.) and water (3×25 ml.). The organic phase was washed with 2M hydrochloric acid, saturated sodium hydrogen carbonate solution (2×25 ml.) and finally with water (2×25 ml.), and then dried (MgSO4) and evaporated. The residual oil crystallised on treatment with ethanol to give 2-hexadecanoyloxy-1-(hexadecanoyloxymethyl)ethyl 4-benzyloxycarbonyl-3,3-dimethylbutyrate as a white solid (2.5 g.). The cooled reaction mixture was partitioned between saturated sodium carbonate solution (50 ml.) and ether (50 ml.) The aqueous layer was separated extracted with ether The extracts were evaporated The residual yellow oil (4.6 g.) was purified by chromatography on silica gel with methylene chloride as eluant

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

Procedure: 3,3-Dimethylglutaric anhydride (5.0 g.) and benzyl alcohol (11 ml.) were heated together at 150° C. for 16 hours. The cooled reaction mixture was partitioned between saturated sodium carbonate solution (50 ml.) and ether (50 ml.). The aqueous layer was separated, acidified with 2M hydrochloric acid and extracted with ether. The extracts were evaporated. The residual yellow oil (4.6 g.) was purified by chromatography on silica gel with methylene chloride as eluant to give benzyl hydrogen 3,3-dimethylglutarate as an oil (1.5 g.); NMR (CDCl3): 1.1 (6H,s, CH3), 2.45+2.47 (4H, 2s, COCH2), 5.12 (2H,s, OCH2), 7.37 (5H, s, aromatic H), 8.45 (1H, br.s, CO2H)ppm. This benzyl ester (1.5 g.) was dissolved in methylene chloride (15 ml.) and stirred with thionyl chloride (2.2 ml.) and N,N-dimethylformamide (DMF) (0.3 ml.) for 3 hours. The solvent was evaporated and the residue was dissolved in dry toluene (15 ml.) and the solution re-evaporated. This was repeated twice to remove excess thionyl chloride. The residual oil (1.5 g.) containing crude benzyl 4-chloroformyl-3,3-dimethylbutyrate was dissolved in methylene chloride (25 ml.). The solution was added to a cooled solution of 1,3-dipalmitin (1.4 g.) in methylene chloride (25 ml.) containing pyridine (0.32 ml.). The mixture was stirred for 2 hours at 0°-5° C. and then for 46 hours at ambient temperature. The solvent was evaporated and the residue was partitioned between ether (70 ml.) and water (3×25 ml.). The organic phase was washed with 2M hydrochloric acid, saturated sodium hydrogen carbonate solution (2×25 ml.) and finally with water (2×25 ml.), and then dried (MgSO4) and evaporated. The residual oil crystallised on treatment with ethanol to give 2-hexadecanoyloxy-1-(hexadecanoyloxymethyl)ethyl 4-benzyloxycarbonyl-3,3-dimethylbutyrate as a white solid (2.5 g.). The cooled reaction mixture was partitioned between saturated sodium carbonate solution (50 ml.) and ether (50 ml.) The aqueous layer was separated extracted with ether The extracts were evaporated The residual yellow oil (4.6 g.) was purified by chromatography on silica gel with methylene chloride as eluant

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

Procedure: A solution of 3,3-dimethylglutaric anhydride in dry THF (60 cm3) was added over 30 min. to lithium aluminum hydride in dry THF (300 cm3) under nitrogen at 0° C. The mixture was then brought gradually up-to reflux. After 3 h, the mixure was cooled, treated with water (3.3 cm3), sodium hydroxide solution (15%, 3.3 cm3) and water (9.9 cm3). The mixture was then filtered, the precipitate extracted with EtOAc (×3), and the combined organics evaporated to afford 3,3-dimethyl-1,5-pentanediol (quantitative yield); 1H NMR (CDCl3) δ 0.95 (s, 6H), 1.57 (t, 4H, J=6.3 Hz), 3.75 (t, 4H, J=6.3 Hz). The mixture was then brought gradually up-to reflux the mixure was cooled The mixture was then filtered the precipitate extracted with EtOAc (×3) the combined organics evaporated