Thiepine
Thiepins are a group of unsaturated seven-membered sulfur- containing heterocycles that are derived from thiepin. Thiepin itself is an unstable compound and cannot be obtained in pure form, but a number of its derivatives are known. The fully hydrogenated derivative is the thiepan .
properties
The Thieping skeleton has the empirical formula C 6 H 6 S and has a system of eight π electrons . Thiepine belong to the group of anti-aromatics . The ring is not planar, but is in a tub conformation. Thiepines are unstable compounds that tend to split off sulfur to form benzene derivatives . A thianorcaradiene intermediate is formed here, from which a benzene derivative is ultimately formed with elimination of sulfur. The driving force behind this reaction is the formation of an aromatic system.
stabilization
Thiepines can be stabilized by substituents which make the formation of the planar thianorcaradiene ring difficult. These include, for example, sterically demanding alkyl radicals , such as tert-butyl radicals . So has 2,7-di- tert -butylthiepin in boiling toluene a half-life of 365 hours. Substituents on carbon atoms C3 and C6 also have a stabilizing effect. On the other hand, if there are two substituents at positions C4 and C5, these usually have a destabilizing effect. The reason for this is that these substituents interfere more strongly in the seven-membered ring than in the six-membered ring. The decomposition to the benzene derivative thus causes relaxation.
use
There are drugs whose active substances are thiepine derivatives. These include the atypical neuroleptic Zotepin and the antidepressant Dosulepin .
literature
R. Gleiter, G. Krennrich, D. Cremer, K. Yamamoto, I. Murata: Electronic Structure and Stability of Thiepins. Photoelectron spectroscopic investigation. , J. Am. Chem. Soc. 1985 , 107 , 6874-6879.
Individual evidence
- ^ Theophil Eicher , Siegfried Hauptmann , Andreas Speicher: The Chemistry of Heterocycles , Wiley-VCH, 2012, ISBN 978-3-527-32747-8 , pp. 532-533.