Expected and unexpected reactions of 1,3-benzothiazine derivatives, I. Ring transformation of β-lactam-condensed 1,3-benzothiazines into 4,5-dihydro-1,4-benzothiazepines and indolo-1,4-benzothiazepines

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Abstract

The ring-enlargement reactions of monochloro-β-lactam-fused 2-aryl-1,3-benzothiazines revealed that the reactions of ortho-nitro aryl-substituted derivatives with sodium methoxide in methanol provided two products, depending on the amount of the base. With 2 equiv of reagent, the expected 1,4-benzothiazepines were obtained. Somewhat surprisingly, treatment with a large excess of sodium methoxide led to the formation of indolo-1,4-benzothiazepines via a novel rearrangement. The structures of the new ring systems were determined by means of X-ray crystallography and NMR spectroscopy.

Original languageEnglish
Pages (from-to)224-227
Number of pages4
JournalTetrahedron Letters
Volume52
Issue number2
DOIs
Publication statusPublished - jan. 12 2011

Fingerprint

Lactams
Methanol
Derivatives
X ray crystallography
X Ray Crystallography
Nuclear magnetic resonance spectroscopy
Magnetic Resonance Spectroscopy

ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry
  • Drug Discovery

Cite this

@article{78e346019c80490eb0ef6ee54772bfc8,
title = "Expected and unexpected reactions of 1,3-benzothiazine derivatives, I. Ring transformation of β-lactam-condensed 1,3-benzothiazines into 4,5-dihydro-1,4-benzothiazepines and indolo-1,4-benzothiazepines",
abstract = "The ring-enlargement reactions of monochloro-β-lactam-fused 2-aryl-1,3-benzothiazines revealed that the reactions of ortho-nitro aryl-substituted derivatives with sodium methoxide in methanol provided two products, depending on the amount of the base. With 2 equiv of reagent, the expected 1,4-benzothiazepines were obtained. Somewhat surprisingly, treatment with a large excess of sodium methoxide led to the formation of indolo-1,4-benzothiazepines via a novel rearrangement. The structures of the new ring systems were determined by means of X-ray crystallography and NMR spectroscopy.",
keywords = "β-Lactam, 1,3-Benzothiazine, Indolo-1,4-benzothiazepine, Ring enlargement",
author = "L. Fodor and P. Csom{\'o}s and Tam{\'a}s Holczbauer and A. K{\'a}lm{\'a}n and A. Cs{\'a}mpai and P. Soh{\'a}r",
year = "2011",
month = "1",
day = "12",
doi = "10.1016/j.tetlet.2010.10.160",
language = "English",
volume = "52",
pages = "224--227",
journal = "Tetrahedron Letters",
issn = "0040-4039",
publisher = "Elsevier Limited",
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TY - JOUR

T1 - Expected and unexpected reactions of 1,3-benzothiazine derivatives, I. Ring transformation of β-lactam-condensed 1,3-benzothiazines into 4,5-dihydro-1,4-benzothiazepines and indolo-1,4-benzothiazepines

AU - Fodor, L.

AU - Csomós, P.

AU - Holczbauer, Tamás

AU - Kálmán, A.

AU - Csámpai, A.

AU - Sohár, P.

PY - 2011/1/12

Y1 - 2011/1/12

N2 - The ring-enlargement reactions of monochloro-β-lactam-fused 2-aryl-1,3-benzothiazines revealed that the reactions of ortho-nitro aryl-substituted derivatives with sodium methoxide in methanol provided two products, depending on the amount of the base. With 2 equiv of reagent, the expected 1,4-benzothiazepines were obtained. Somewhat surprisingly, treatment with a large excess of sodium methoxide led to the formation of indolo-1,4-benzothiazepines via a novel rearrangement. The structures of the new ring systems were determined by means of X-ray crystallography and NMR spectroscopy.

AB - The ring-enlargement reactions of monochloro-β-lactam-fused 2-aryl-1,3-benzothiazines revealed that the reactions of ortho-nitro aryl-substituted derivatives with sodium methoxide in methanol provided two products, depending on the amount of the base. With 2 equiv of reagent, the expected 1,4-benzothiazepines were obtained. Somewhat surprisingly, treatment with a large excess of sodium methoxide led to the formation of indolo-1,4-benzothiazepines via a novel rearrangement. The structures of the new ring systems were determined by means of X-ray crystallography and NMR spectroscopy.

KW - β-Lactam

KW - 1,3-Benzothiazine

KW - Indolo-1,4-benzothiazepine

KW - Ring enlargement

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U2 - 10.1016/j.tetlet.2010.10.160

DO - 10.1016/j.tetlet.2010.10.160

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EP - 227

JO - Tetrahedron Letters

JF - Tetrahedron Letters

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