On the mechanism of conversion of 4-carboxy-3,4-dihydro-3-phenyl-1(2H)-isoquinolones to indeno[1,2-c]isoquinolines by thionyl chloride

Xiangshu Xiao, Andrew Morrell, Phillip E. Fanwick, Mark Cushman

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

It has been known for a long time that thionyl chloride can effectively mediate the transformation of 4-carboxy-3,4-dihydro-3-phenyl-1(2H)-isoquinolones to indeno[1,2-c]isoquinolines. The mechanism of this unique transformation, however, remains to be established. Evidence is presented to demonstrate that (1) the two-electron dehydrogenation precedes Friedel-Crafts cyclization and (2) the two-electron dehydrogenation occurs via H-4 deprotonation and subsequent O-sulfinylation of the lactam moiety instead of C-sulfinylation of the carbon α to the carboxyl group.

Original languageEnglish (US)
Pages (from-to)9705-9712
Number of pages8
JournalTetrahedron
Volume62
Issue number41
DOIs
StatePublished - Oct 9 2006
Externally publishedYes

Fingerprint

Isoquinolines
Dehydrogenation
Electrons
Lactams
Deprotonation
Cyclization
Carbon
thionyl chloride

Keywords

  • Indenoisoquinoline
  • Intramolecular Friedel-Crafts reaction
  • Oxidation
  • Thionyl chloride

ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry
  • Drug Discovery

Cite this

On the mechanism of conversion of 4-carboxy-3,4-dihydro-3-phenyl-1(2H)-isoquinolones to indeno[1,2-c]isoquinolines by thionyl chloride. / Xiao, Xiangshu; Morrell, Andrew; Fanwick, Phillip E.; Cushman, Mark.

In: Tetrahedron, Vol. 62, No. 41, 09.10.2006, p. 9705-9712.

Research output: Contribution to journalArticle

Xiao, Xiangshu ; Morrell, Andrew ; Fanwick, Phillip E. ; Cushman, Mark. / On the mechanism of conversion of 4-carboxy-3,4-dihydro-3-phenyl-1(2H)-isoquinolones to indeno[1,2-c]isoquinolines by thionyl chloride. In: Tetrahedron. 2006 ; Vol. 62, No. 41. pp. 9705-9712.
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AB - It has been known for a long time that thionyl chloride can effectively mediate the transformation of 4-carboxy-3,4-dihydro-3-phenyl-1(2H)-isoquinolones to indeno[1,2-c]isoquinolines. The mechanism of this unique transformation, however, remains to be established. Evidence is presented to demonstrate that (1) the two-electron dehydrogenation precedes Friedel-Crafts cyclization and (2) the two-electron dehydrogenation occurs via H-4 deprotonation and subsequent O-sulfinylation of the lactam moiety instead of C-sulfinylation of the carbon α to the carboxyl group.

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