2-Lithio-3-methoxy-1,3-dimethylcyclopentene: A synthetic equivalent of 2-lithio-1,3-dimethylcyclopentadiene and useful synthon for 6-alkyl-1,4- dimethylfulvenes and ansa-metallocene complexes

Young Chul Won, Ui Gab Joung, Eun Sook Cho, Bun Yeoul Lee, Hyosun Lee, Young Whan Park, Kwang Ho Song

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

2-Bromo-3-methoxy-1,3-dimethylcyclopentene (3). is synthesized in 85% yield in 80 g scale by 1,2-addition of MeLi to 2-bromo-3-methyl-2-cyclopenten-1-one and subsequent in situ treatment of MeI. Addition of n-BuLi to the bromo-compound 3 in Et2O affords 2-lithio-3-methoxy-1,3- dimethylcyclopentene (1). Successive addition of RCHO [R = CH3, (CH2)2CH3, CH(CH3)2, C(CH3)3, H] and MeI to the lithium compound and aqueous acidic work-up provide cyclopentadiene compounds, 2-[CHR(OMe)]-1,3-Me 2C5H3 in 60-84% yields. Treatment of the cyclopentadienes with NaH or KH in pentane affords 1,4,6-trimethylfulvene, 6-n-propyl-1,4-dimethylfulvene, 6-isopropyl-1,4-dimethylfulvene, 6-tert-butyl-1,4-dimethylfulvene and 1,4-dimethylfulvenein 67-83% yields. Ligand for an ansa-metallocene complex, CH2C(1,3-Me2Cp) 2ZrCl2, can be shortly afforded in 64% yield by reacting the lithium compound 1 with the newly synthesized 1,4-dimethylfulvene.

Original languageEnglish
Pages (from-to)1052-1056
Number of pages5
JournalSynthesis
Issue number7
DOIs
Publication statusPublished - 2004 May 6

Keywords

  • Cyclopentadienes
  • Fulvene synthesis
  • Lithiation
  • Metallocenes
  • Organometallic reagents

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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