The first total synthesis of (R)-7-butyl-6,8-dihydroxy-3-pentylisochroman-1-one

The enantioselective synthesis of 7-butyl-6,8-dihydroxy-(3R)-pentylisochroman-1-one has been achieved for the first time in which Sharpless asymmetric dihydroxylation is the key step.

Figure optionsDownload as PowerPoint slide

(1R,2R)-1-(4-Butyl-3,5-dimethoxyphenyl)heptane-1,2-diolC19H32O4Ee 95%[α]D25=-3 (c 1.0, CH3OH)Source of chirality: enantioselective synthesisAbsolute configuration: 1R,2R

(R)-1-(4-Butyl-3,5-dimethoxyphenyl)heptan-2-olC19H32O3Ee 93%[α]D25=-12 (c 1.0, CH3OH)Source of chirality: enantioselective synthesisAbsolute configuration: R

2-Butyl-1,3-dimethoxy-5-((R)-2-methoxyheptyl)benzeneC20H34O3Ee 93%[α]D25=+14 (c 1.0, CH3OH)Source of chirality: enantioselective synthesisAbsolute configuration: R

2-Bromo-4-butyl-3,5-dimethoxy-1-((R)-2-methoxyheptyl)benzeneC20H33BrO3Ee 93%[α]D25=-4 (c 1.0, CH3OH)Source of chirality: enantioselective synthesisAbsolute configuration: R

Ethyl 3-butyl-2,4-dimethoxy-6-((R)-2-methoxyheptyl)benzoateC23H38O5Ee 93%[α]D25=+12 (c 1.02, CH3OH)Source of chirality: enantioselective synthesisAbsolute configuration: R

7-Butyl-6,8-dihydroxy-3(R)-pentylisochroman-1-oneC18H26O4Ee 93%[α]D25=-24 (c 0.1, CH3OH)Source of chirality: enantioselective synthesisAbsolute configuration: R