Water → HCID 15676252, compound

Participants

Reaction Conditions

Reaction Steps

17.6 g (37.1mmol) of (1S,5R,6S,7R)-7-benzoyloxy-6-[(E)-(3R,4S)-2 -bromo-3-hydroxy-4-methyl-1-nonen-6-inyl]-2-oxabicyclo[3.3.0]octan-3-one (for preparation see EP0284547) is dissolved in 260 ml of acetone, cooled under an atmosphere of dry argon to -30° C. and 20 ml of a standardized Jones solution is instilled within 10 minutes. It is stirred for another 1.5 hours at -20° C., excess oxidizing agent is decomposed by adding 25 ml of isopropanol, allowed to heat to 20° C., mixed with 300 ml of water and extracted several times with a total of 600 ml of diethyl ether. The combined organic extracts are washed with water and saturated sodium chloride solution until neutral reaction, dried on magnesium sulfate and the residue obtained after filtration and removal of the solvent is purified by chromatography on about 800 ml of fine silica gel by using an n-hexane/ethyl acetate mixture. In addition to 11.3 g (23.9 mmol, 64%) of (1S,5R,6S,7R)-7-benzoyloxy-6-[(E)-(4S)-2-brom-3-oxo-4-methyl-1-nonen-6-inyl]-2-oxa-bicyclo[3.3.0]octan- 3-one, 3.59 g (7.58 mmol, 26%) of (1S,5R,6R,7R)-7-benzoyloxy-6-[(Z)-(4S)-1-oxo-2-bromo-4-methyl-non-2-en-6-inyl]-2-oxabicyclo[3.3.0]octan-3-one is isolated. The latter compound is dissolved in 45 ml of anhydrous methanol, cooled under an atmosphere of dry argon to -45° C., mixed in portions with a total of 520 mg of sodium borohydride and stirred for 30 more minutes at -45° C. Excess reducing agent is decomposed by adding 0.8 ml of acetone, allowed to heat to 20° C., mixed with water and extracted several times with diethyl ether. The combined organic extracts are washed with water and saturated sodium chloride solution until neutral reaction, dried magnesium sulfate and the residue obtained after filtration and removal of the solvent is purified by chromatography on about 200 ml of fine silica gel by using a dichloromethane/ethyl ether mixture. 1.79 g (3.76 mmol, 50%) of the nonpolar alcohol as well as 528 mg (1.11 mmol, 15%) of the polar alcohol are isolated.

Provenance & Evidence