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Stereocontrolled synthesis of carbocyclic compounds with a quaternary carbon atom based on SN2 ' alkylation of γ,δ-epoxy-α,β-unsaturated ketones

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Title: Stereocontrolled synthesis of carbocyclic compounds with a quaternary carbon atom based on SN2 ' alkylation of γ,δ-epoxy-α,β-unsaturated ketones
Authors: Yoshimura, Fumihiko Browse this author →KAKEN DB
Kowata, Ayano Browse this author
Tanino, Keiji Browse this author →KAKEN DB
Issue Date: 28-Jul-2012
Publisher: Royal Society of Chemistry
Journal Title: Organic & Biomolecular Chemistry
Volume: 10
Issue: 28
Start Page: 5431
End Page: 5442
Publisher DOI: 10.1039/c2ob25719j
PMID: 22706976
Abstract: We developed a new method for stereoselective construction of an all-carbon quaternary stereogenic center on a carbocyclic ring based on regio- and stereoselective SN2' alkylation reactions of γ,δ-epoxy-α,β-unsaturated cyclic ketones. Treatment of the ketones, which were readily prepared in enantiomerically pure form by means of aldol condensations between 3-ethoxy-2-cycloalkenones and α,β-epoxy aldehydes, with a R2Zn-CuCN reagent afforded anti-SN2' products stereoselectively. Conversely, the corresponding syn-SN2' products were stereoselectively obtained through two-step transformations of the same γ,δ-epoxy-α,β-unsaturated cyclic ketones: (1) conversion of the epoxide moiety to a chlorohydrin by treatment with MgCl2 and (2) subsequent SN2' substitution of the chlorohydrin with a R2Zn-CuCN reagent. These substitution products with their chiral trans-allylic alcohol moieties are promising precursors for complex molecules. For example, Eschenmoser-Claisen rearrangement of one of the substitution products resulted in stereoselective formation of a keto amide having contiguous quaternary and tertiary stereogenic centers.
Rights: Org. Biomol. Chem., 2012,10, 5431-5442 - Reproduced by permission of The Royal Society of Chemistry (RSC)
Type: article (author version)
URI: http://hdl.handle.net/2115/52793
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 吉村 文彦

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