The importance of solvent effects of the diastereoreduction of acyclic ketones

DOI

Bibliographic Information

Other Title
  • 鎖状ケトンの面選択ヒドリド還元における溶媒効果

Description

LiAlH4 reduction of acyclic carbonyl compounds possessing a heteroatom at the a-position (R = Me) give R*,S*-diastereoisomers predominantly via Re attack. These diastereoselectivities are interpreted in terms of the chelation model, where Li interacts with both oxygen atoms of the substrate ketones. However, stereochemical reversal is observed if a large substituent, such as aryloxy group, is introduced at the a-position (R = Aryl). Theoretical calculations at the B3LYP/6-31+G(d,p) level on the reduction of a-aryloxy ketones with LiAlH4 assuming the chelated transition state could not reproduce the reversal of stereoselectivity. Therefore calculations were performed using the non-chelated transition state models with a few solvent molecules (dimethyl ether). It was found that two solvent molecules coordinate with lithium ion throughout the reaction and that they sterically prevent the formation of the chelated transition structure. Optimized transition structures with two dimethyl ether molecules at the Li nicely reproduced the observed data.

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Details 詳細情報について

  • CRID
    1390001205556000768
  • NII Article ID
    130004645474
  • DOI
    10.11494/kisoyuki.2008.0.344.0
  • Text Lang
    ja
  • Data Source
    • JaLC
    • CiNii Articles
  • Abstract License Flag
    Disallowed

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