Modified Riemschneider Reaction of 3‐Thiocyanatoquinolinediones |
| |
Authors: | Ondřej Rudolf Vladimír Mrkvička Antonín Lyčka Michal Rouchal Antonín Klásek |
| |
Institution: | 1. Department of Chemistry, Faculty of Technology, Tomas Bata University, CZ‐76272 Zlin;2. Research Institute for Organic Syntheses (VUOS), Rybitví 296, CZ‐53354 Pardubice 20 |
| |
Abstract: | The Riemschneider reaction of 3‐thiocyanatoquinoline‐2,4(1H,3H)‐diones with conc. H2SO4 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]thiazolo5,4‐c]quinoline‐2,4‐diones and 1,9b‐dihydro‐9b‐hydroxythiazolo5,4‐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]oxathiolo4,5‐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, 1H‐ and 13C‐NMR, and EI and ESI mass spectra, and in some cases, 15N‐NMR spectra were also used to characterize new compounds. |
| |
Keywords: | Dealkylation Riemschneider reaction Oxathioloquinolinediones Thiazoloquinolinediones Thiocyanates |
|
|