1993 Fiscal Year Final Research Report Summary
Structure of New Chiral Organoheterocuprate and Enantioselective Conjugate Addition
| Project/Area Number |
04453022
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
有機化学一般
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
TANAKA Kazuhiko Kyoto Univ., Science, Associate Professor, 理学部, 助教授 (00025446)
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| Project Period (FY) |
1992 – 1993
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| Keywords | (R)-muscone / enantioselectivity / alkoxydimethylcuprate / amplification / homochiral / C_2 symmetry / asymmetric / (E)-2-cyclopentadecenone |
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| Research Abstract |
1. (R)-Muscone was obtained in 100% optical purity and 93% chemical yield by conjugate addition of chiral organohcterocuprate, derived from (1R,2R,3S,4S)-3-[(1-methylpyrrol-2-yl)-methyl-amino]-1,7,7-trimethl-bicyclo[2.2.1]heptan-2-ol(endo-MPATH), MeLi, Cul, and MeLi, to (E)-2-cyclopentadecenone in toluene-THF solvent system at-78ﾟC.
2. Actual reactive species that afforded high enantioselectivity and high chemical yield was found to be alkoxydimehtylcuprate derived from copper alkoxide of endo-MPATH(1 equiv.)and methyllithium(2 equiv.).
3. The first chiral amplification in organocuprate conjugate addition was observed. This phenomenon can be explained by considering that the reaction proceeds through dimeric clusters such as homochiral dimer possessing C_2 symmetry and heterochiral dimer, which possess different reactivity and stability.
4.This conjugate addition reaction is also effective for other (10-18-membered) macrocyclic enones. Chiral ketones with R-confiurarion were obtained in good chemical and optical yields from (E)-enones. In the case of (Z)-enones, reversed stereoselectivity was observed. The results can be explained by assuming the topside approach of a methyl group of the alkoxydimethylcuprate to the beta carbon to form ketones regardless of the geometry of the cyclic enones.
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