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Modified Riemschneider Reaction of 3‐Thiocyanatoquinolinediones
Author(s) -
Rudolf Ondřej,
Mrkvička Vladimír,
Lyčka Antonín,
Rouchal Michal,
Klásek Antonín
Publication year - 2012
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.201200049
Subject(s) - chemistry , quinoline , reaction conditions , mass spectrum , medicinal chemistry , reaction mechanism , nmr spectra database , group (periodic table) , stereochemistry , mass spectrometry , organic chemistry , spectral line , catalysis , chromatography , astronomy , physics
The Riemschneider reaction of 3‐thiocyanatoquinoline‐2,4(1 H ,3 H )‐diones with conc. H 2 SO 4 was investigated. Using different reaction conditions, 13 types of reaction products were isolated. Compounds bearing a Me, Et, or Bu group at C(3) afforded mainly [1,3]thiazolo[5,4‐ c ]quinoline‐2,4‐diones and 1,9b‐dihydro‐9b‐hydroxythiazolo[5,4‐ c ]quinoline‐2,4‐diones. In the case of the 3‐Bu derivatives of the starting compounds, C ‐debutylation was also observed. If a Bn group is present at C(3), rapid C ‐debenzylation of the starting thiocyanates occurred, yielding [1,3]oxathiolo[4,5‐ c ]quinoline‐2,4‐diones, and mixtures of mono‐, di‐, and trisulfides derived from 4‐hydroxy‐3‐sulfanylquinoline‐2‐ones. The reaction mechanism of all of the transformations is discussed. All new compounds were characterized by IR, 1 H‐ and 13 C‐NMR, and EI and ESI mass spectra, and in some cases, 15 N‐NMR spectra were also used to characterize new compounds.