Heterocycles containing two or more sulfur atoms

HETEROCYCLES CONTAINING TWO OR MORE SULFUR ATOMS 6.4.4.1 Dithianes... 

The best-known cyclic sulfur imides are saturated sulfurnitrogen heterocycles, which are derived from cyclo-Sg by the replacement of one or more sulfur atoms by an amido (NH) group. Derivatives containing adjacent NH groups are not found. Thus, the members of this series consist of S7NH (70), three diimides 1,3-, 1,4- and 1,5-S6(NH)2, two triimides 1,3,5- and l,3,6-Ss(NH)3, and S4N4H4 (71). 

In this section, the reactivity of carbon- and heteroatom-containing substituents attached directly or indirectly to the heterocyclic ring of 1,3-dithiole derivatives is discussed. Here, chemical manipulations on these systems exclude ring carbon and sulfur atoms, which are the subject of Section 4.12.6. Special 1,3-dithioles called Jt-extended TTFs, containing two or more 1,3-dithiole moieties linked together via =C-(C=C) -C= or similar conjugated spacers, are discussed with typical TTFs in Section 4.12.11, although formally they constitute an example of functionalization of the 1,3-dithiole by 2rt-extended substituents, terminated by another 1,3-dithiole moiety. 

The present review includes data on the synthesis and chemical properties of the fluorine containing derivatives of furan, thiophene, selenophene, phospholene, and hve-membered heterocycles with two or more oxygen and sulfur atoms pubhshed prior 2007. Every section starts with discussion on the synthetic methods for unsaturated heterocycles (furan, thiophene etc.) and is followed by synthesis and transformations of dihydro and tetrahydro derivatives. 

Five-membered fluorine-containing heterocyclic compounds with two or three sulfur atoms are more extended. A ring expansion reaction of thietanes into 1,2-dithiolanes involving heating with sulfur was used. ... 

A heterocycle is a cyclic compound that contains atoms of two or more elements in its ring, usually carbon along with nitrogen, oxygen, or sulfur. Heterocyclic amines are particularly common, and many have important biological properties. Pyridoxal phosphate, a coenzyme sildenafil (Viagra),... 

Reaction of di-/ -butylcyclopentadiene 76 with excess KOBuc in the presence of elemental sulfur leads to hitherto unknown cyclopentadienes 77 bridged by S-atoms via one or two dithioketal functionalities. Thus, polycyclic compounds with tetrathiepin fragment as well as eight- and more membered heterocyclic rings, containing sulfur and carbon atoms, were formed (Equation 14) <2000ICA184>. 

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