Cycloadditions in Syntheses. LII. Stereochemical Pathways of 1-Isoquinolone-Chloroethylene Photo [2 + 2] cycloaddition: Determination of Regio- and Stereostructures of the Products and Explanation for Their Formation

Takuo Chiba, Yoshihiro Takada, Chikara Kaneko, Fumiyuki Kiuchi, Yoshisuke Tsuda

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The cycloaddition of isoquinolone and its N-methyl derivative to all the chlorinated ethylenes has been studied. The structures of all of the photoadducts were determined on the basis of X-ray crystallographic analysis as well as nuclear magnetic resonance spectroscopy and it was found that the cyclobutane rings in the adducts took puckered conformation. The details of the two-step closure process via biradical intermediates are discussed and it is concluded that σ-bond rotation prior to spin relaxation in the biradical intermediates takes a primary role in determination of the stereochemical outcome. The interesting fact that more trans products are formed from cis-dichloroethylene and more cis products from trans-dichloroethylene can also be explained in terms of the present proposal.

Original languageEnglish
Pages (from-to)3317-3325
Number of pages9
JournalChemical and Pharmaceutical Bulletin
Volume38
Issue number12
DOIs
Publication statusPublished - 1990 Jan 1
Externally publishedYes

Keywords

  • X-ray analysis
  • biradical intermediate
  • conformation
  • conformation
  • cyclobutane
  • halogenated ethylene
  • isoquinolone
  • photocycloaddition
  • puckered

ASJC Scopus subject areas

  • Chemistry(all)
  • Drug Discovery

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