One-carbon ring-expansion of 2-substituted cyclohexanones via lithium- and magnesium β-oxido carbenoid rearrangement

a new synthesis of 2,7-disubstituted and 2,2,7-trisubstituted cycloheptanones

Tsuyoshi Satoh, Shu Tanaka, Naoyuki Asakawa

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Lithium α-sulfinyl carbanion of 1-chloroethyl p-tolyl sulfoxide was reacted with 2-substituted cyclohexanones to afford adducts in good yields. The adducts were treated with LDA or t-BuMgCl to give lithium or magnesium alkoxides, which were treated with t-BuLi or i-PrMgCl to afford one-carbon ring-expanded 2,7-disubstituted cycloheptanones through β-oxido carbenoids. Interestingly, 2,3-disubstituted cycloheptanones were obtained in a trace amount or were not obtained at all. The enolate intermediates of this reaction were found to be able to get trapped with electrophiles to give 2,2,7-trisubstituted cycloheptanones in moderate to good yields. This method is very useful for the synthesis of 2,7-disubstituted cycloheptanones and 2,2,7-trisubstituted cycloheptanones from 2-substituted cyclohexanones in only two steps.

Original languageEnglish
Pages (from-to)6769-6773
Number of pages5
JournalTetrahedron Letters
Volume47
Issue number38
DOIs
Publication statusPublished - 2006 Sep 18
Externally publishedYes

Fingerprint

Cyclohexanones
Lithium
Magnesium
Carbon
sulfoxide
cycloheptanone

Keywords

  • β-Oxido carbenoid rearrangement
  • 2,2,7-Trisubstituted cycloheptanone
  • 2,7-Disubstituted cycloheptanone
  • One-carbon ring-expansion
  • Sulfoxide

ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry
  • Drug Discovery

Cite this

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abstract = "Lithium α-sulfinyl carbanion of 1-chloroethyl p-tolyl sulfoxide was reacted with 2-substituted cyclohexanones to afford adducts in good yields. The adducts were treated with LDA or t-BuMgCl to give lithium or magnesium alkoxides, which were treated with t-BuLi or i-PrMgCl to afford one-carbon ring-expanded 2,7-disubstituted cycloheptanones through β-oxido carbenoids. Interestingly, 2,3-disubstituted cycloheptanones were obtained in a trace amount or were not obtained at all. The enolate intermediates of this reaction were found to be able to get trapped with electrophiles to give 2,2,7-trisubstituted cycloheptanones in moderate to good yields. This method is very useful for the synthesis of 2,7-disubstituted cycloheptanones and 2,2,7-trisubstituted cycloheptanones from 2-substituted cyclohexanones in only two steps.",
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AU - Tanaka, Shu

AU - Asakawa, Naoyuki

PY - 2006/9/18

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N2 - Lithium α-sulfinyl carbanion of 1-chloroethyl p-tolyl sulfoxide was reacted with 2-substituted cyclohexanones to afford adducts in good yields. The adducts were treated with LDA or t-BuMgCl to give lithium or magnesium alkoxides, which were treated with t-BuLi or i-PrMgCl to afford one-carbon ring-expanded 2,7-disubstituted cycloheptanones through β-oxido carbenoids. Interestingly, 2,3-disubstituted cycloheptanones were obtained in a trace amount or were not obtained at all. The enolate intermediates of this reaction were found to be able to get trapped with electrophiles to give 2,2,7-trisubstituted cycloheptanones in moderate to good yields. This method is very useful for the synthesis of 2,7-disubstituted cycloheptanones and 2,2,7-trisubstituted cycloheptanones from 2-substituted cyclohexanones in only two steps.

AB - Lithium α-sulfinyl carbanion of 1-chloroethyl p-tolyl sulfoxide was reacted with 2-substituted cyclohexanones to afford adducts in good yields. The adducts were treated with LDA or t-BuMgCl to give lithium or magnesium alkoxides, which were treated with t-BuLi or i-PrMgCl to afford one-carbon ring-expanded 2,7-disubstituted cycloheptanones through β-oxido carbenoids. Interestingly, 2,3-disubstituted cycloheptanones were obtained in a trace amount or were not obtained at all. The enolate intermediates of this reaction were found to be able to get trapped with electrophiles to give 2,2,7-trisubstituted cycloheptanones in moderate to good yields. This method is very useful for the synthesis of 2,7-disubstituted cycloheptanones and 2,2,7-trisubstituted cycloheptanones from 2-substituted cyclohexanones in only two steps.

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KW - Sulfoxide

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