A useful ring transformation route to novel thiazepino[7,6-b]indoles from monochloro-β-lactam-fused 1,3-thiazino[6,5-b]indoles, analogues of cyclobrassinin

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Abstract

The Staudinger ketene-imine cycloaddition reactions of cyclobrassinin phytoalexin analogues 2-aryl-4,9-dihydro-1,3-thiazino[6,5-b]indoles with chloroacetyl chloride as a ketene source were investigated under different conditions. Both β-lactam ring formation and the N-chloroacetylation of the indole moiety took place. The indole N-chloroacetyl group can be easily removed by treatment in the presence of silica gel in methanol at reflux temperature. The selective β-lactam formation can be also achieved in certain cases under milder Staudinger conditions. The treatment of azeto[2,1-b]thiazino[6,5-b]indole-1-one derivatives with sodium ethoxide in ethanol provided the novel thiazepino[7,6-b]indole ring systems in a one-step ring transformation. The structures of the new ring systems were determined by means of IR and NMR spectroscopy.

Original languageEnglish
JournalTetrahedron
DOIs
Publication statusAccepted/In press - Nov 26 2016

Fingerprint

Indoles
Lactams
Imines
Cycloaddition
Silica Gel
Cycloaddition Reaction
Nuclear magnetic resonance spectroscopy
Methanol
Infrared spectroscopy
Ethanol
Magnetic Resonance Spectroscopy
Derivatives
Temperature
indole
cyclobrassinin
ketene

Keywords

  • Indole protection
  • Ring transformation
  • Staudinger cycloaddition
  • Thiazepino[7,6-b]indoles
  • β-Lactam

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

Cite this

@article{2875a8e4b4424c6f8baf11c95bd533e1,
title = "A useful ring transformation route to novel thiazepino[7,6-b]indoles from monochloro-β-lactam-fused 1,3-thiazino[6,5-b]indoles, analogues of cyclobrassinin",
abstract = "The Staudinger ketene-imine cycloaddition reactions of cyclobrassinin phytoalexin analogues 2-aryl-4,9-dihydro-1,3-thiazino[6,5-b]indoles with chloroacetyl chloride as a ketene source were investigated under different conditions. Both β-lactam ring formation and the N-chloroacetylation of the indole moiety took place. The indole N-chloroacetyl group can be easily removed by treatment in the presence of silica gel in methanol at reflux temperature. The selective β-lactam formation can be also achieved in certain cases under milder Staudinger conditions. The treatment of azeto[2,1-b]thiazino[6,5-b]indole-1-one derivatives with sodium ethoxide in ethanol provided the novel thiazepino[7,6-b]indole ring systems in a one-step ring transformation. The structures of the new ring systems were determined by means of IR and NMR spectroscopy.",
keywords = "Indole protection, Ring transformation, Staudinger cycloaddition, Thiazepino[7,6-b]indoles, β-Lactam",
author = "P. Csom{\'o}s and L. Fodor and A. Cs{\'a}mpai and P. Soh{\'a}r",
year = "2016",
month = "11",
day = "26",
doi = "10.1016/j.tet.2017.03.047",
language = "English",
journal = "Tetrahedron",
issn = "0040-4020",
publisher = "Elsevier Limited",

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TY - JOUR

T1 - A useful ring transformation route to novel thiazepino[7,6-b]indoles from monochloro-β-lactam-fused 1,3-thiazino[6,5-b]indoles, analogues of cyclobrassinin

AU - Csomós, P.

AU - Fodor, L.

AU - Csámpai, A.

AU - Sohár, P.

PY - 2016/11/26

Y1 - 2016/11/26

N2 - The Staudinger ketene-imine cycloaddition reactions of cyclobrassinin phytoalexin analogues 2-aryl-4,9-dihydro-1,3-thiazino[6,5-b]indoles with chloroacetyl chloride as a ketene source were investigated under different conditions. Both β-lactam ring formation and the N-chloroacetylation of the indole moiety took place. The indole N-chloroacetyl group can be easily removed by treatment in the presence of silica gel in methanol at reflux temperature. The selective β-lactam formation can be also achieved in certain cases under milder Staudinger conditions. The treatment of azeto[2,1-b]thiazino[6,5-b]indole-1-one derivatives with sodium ethoxide in ethanol provided the novel thiazepino[7,6-b]indole ring systems in a one-step ring transformation. The structures of the new ring systems were determined by means of IR and NMR spectroscopy.

AB - The Staudinger ketene-imine cycloaddition reactions of cyclobrassinin phytoalexin analogues 2-aryl-4,9-dihydro-1,3-thiazino[6,5-b]indoles with chloroacetyl chloride as a ketene source were investigated under different conditions. Both β-lactam ring formation and the N-chloroacetylation of the indole moiety took place. The indole N-chloroacetyl group can be easily removed by treatment in the presence of silica gel in methanol at reflux temperature. The selective β-lactam formation can be also achieved in certain cases under milder Staudinger conditions. The treatment of azeto[2,1-b]thiazino[6,5-b]indole-1-one derivatives with sodium ethoxide in ethanol provided the novel thiazepino[7,6-b]indole ring systems in a one-step ring transformation. The structures of the new ring systems were determined by means of IR and NMR spectroscopy.

KW - Indole protection

KW - Ring transformation

KW - Staudinger cycloaddition

KW - Thiazepino[7,6-b]indoles

KW - β-Lactam

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