| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2005: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
In the course of studies on "Synthesis of Novel Phosphonoacetates Bearing a Stereogenic Phosphorous Atom and Application to Asymmetric HWE Reaction", we have synthesized novel P-stereogenic phosphonoacetates. We have also developed several new reactions, such as asymmetric Horner-Wadsworth-Emmons (HWE) reactions and deconjugative esterification.
Racemic phosphonoacetates were readily prepared from methyl bis(2,2,2-trifluoroethyl)phosphonoacetate, a Z-selective HWE reagent, by alcoholysis with various alcohols in the presence of triethylamine or DBU. PLE-catalyzed kinetic resolution of some of these racemic phosphonoacetates proceeded in a highly effective manner to give the novel P-stereogenic phosphonoacetates. A diastereoselective HWE reaction of a P-stereogenic phosphonoacetate bearing (-)-menthol as a chiral auxiliary afforded the corresponding tetrasubstituted olefin in 84% de.
In addition, we demonstrated a novel diastereoselective HWE reaction for the synthesis of tetrasubstituted alkenes with an axis of chirality. An asymmetric HWE reaction of a-symmetric 4-methylcyclohexanone and a novel HWE reagent bearing 0-benzylisoman.nide was investigated by employing Sn(OSO_2CF_3)_2 and N-ethylpiperidine. As a result, a-methyl-a,β-unsaturated ester, a tetrasubstituted alkene with an axis of chirality, was obtained in > 99% de.
On the other hand, 4-(pyrrolidin-1-yl)pyridine-catalyzed deconjugative esterification of 2-cyclohexylidineacetic acids afforded isopropyl 2-(cyclohex-1-enyl)acetate by employing 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as a coupling reagent. Whereas, 4-(pyrrolidin-1-yl)pyridine-catalyzed esterification with 1,3-dicyclohexylcarbodiimide was not accompanied by deconjugation and gave isopropy 2-cyclohexylideneacetate,
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