Synthesis of enantiopure phthalides including 3-butylphthalide, a fragrance component of celery oil, and determination of their absolute configurations.
Enantiopure phthalides 2 and 5-8 were synthesized via enantioresolution of the corresponding alcohols with a chiral auxiliary of camphorsultam dichlorophthalic acid, (1S,2R,4R)-(-)-CSDP acid 3, followed by solvolysis with KOH in MeOH and the catalytic oxidation of chiral glycols with iridium complex 28. The absolute configurations of phthalides 2 and 5-8 were determined by applying the (1)H-NMR anisotropy method of MalphaNP acid (4), 2-methoxy-2-(1-naphthyl)propionic acid, to the chiral synthetic precursory alcohols. In the case of 3-phenylphthalide (R)-(-)-7, the absolute configuration determined by the (1)H-NMR anisotropy method using MalphaNP acid 4 agreed with that by the X-ray crystallographic method. By applying these methods, 3-butylphthalide (S)-(-)-2, a fragrance component of essential oil of celery, has been synthesized in an enantiopure form, and its absolute configuration was unambiguously determined.
Kosaka
Masashi
M
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan.
Sekiguchi
Satoshi
S
Naito
Junpei
J
Uemura
Makoto
M
Kuwahara
Shunsuke
S
Watanabe
Masataka
M
Harada
Nobuyuki
N
Hiroi
Kunio
K
D000438:Alcohols / Q000138:chemical synthesis / Q000737:chemistry; D000077102:Apium / Q000737:chemistry*; D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D004952:Esters; D015394:Molecular Structure; D009822:Oils, Volatile / Q000737:chemistry*; D010476:Perfume / Q000737:chemistry*; D010938:Plant Oils / Q000737:chemistry*; D058428:Silica Gel; D012822:Silicon Dioxide; D013057:Spectrum Analysis; D013237:Stereoisomerism
D000438:Alcohols; D001572:Benzofurans; D004952:Esters; D009822:Oils, Volatile; D010476:Perfume; D010938:Plant Oils; D058428:Silica Gel; D012822:Silicon Dioxide; C082022:phthalide