Thiocarbonyl compounds, and

These reactions differ from those of sulfur tetrafluoride with carbonyl compounds in that a formal oxidation-reduction of the sulfur atoms m the thiocarbonyl compound and sulfur tetrafluoride molecule occurs, resulting in the formation of free sulfur and the complete utilization of the fluorine atoms in sulfur tetrafluoride. 

Tc(V) and Re(V) are thiols, thioethers and thiocarbonyl compounds and molecules containing combinations of their functional groups. There exist significant differences in the ability of the various groups to form stable complexes and in the kind of complexes formed. Unlike thiols, a neutral S-donor shows a preference for the metals in oxidation states lower than +5. 

The use of thiocarbonyl compounds and also trimethylsilyldiazomethane in the Pechmann-Nold synthesis has greatly increased the scope of this reaction in recent years. Wolff s synthesis has also benefited from advances in the synthesis of both diazoketones and thionating reagents. 

Reactions of Phosphorus Ylides with Carbon Disulfide, Stable Thiocarbonyl Compounds, and Thiosilanones... 

The chemistry outlined in Schemes 8.32 and 8.34 illustrates the complexity of reactions that occur between thiocarbonyl compounds and diazo compounds. Heimgartner and co-workers (214-217) observed a similar reactivity pattern when they combined l,3-thiazol-5(477)-thiones (153) with diazoalkanes. When ethyl diazoacetate was used, additional reaction pathways occurred giving rise to a complex mixture of products (218). An interesting aspect of this chemistry involves... 

The cleavage of a S—S bond has been extensively used for the preparation of thiocarbonyl compounds and this elimination can be induced thermally or by base... 

Whereas coordination of a CA to a lone electron pair of a heteroatom containing only single bonds typically results in a hypsochromic shift of the CA absorption maxima, upon complexation of germylenes with S atoms of thiocarbonyl compounds (and also... 

S NMR spectra of thiocarbonyl, thiophosphoryl compounds, and of some sulphonium salts have also been published. Machiguchi et al. have reported the 33S NMR spectrum of tropothione41 2, a thiocarbonyl compound, and of its corresponding S-oxide, 3 and sulphenic acid, 4.42... 

The starting materials are usually thiocarbonyl compounds, and among them thioamides are the most popular. Two routes allow access to S-allylke-tene aminothioacetals from thioamides deprotonation by base followed by S-allylation, or vice versa. 

Carbonyl compounds and other dipolarophiles containing heteroatoms react with miinch-nones. Thus benzaldehyde forms the betaine (245) which suffers ring-cleavage to yield the enamine (246 equation 65). Thiocarbonyl compounds and nitrosobenzene behave in an analogous manner. The action of dipolarophiles containing cumulative double bonds results in the formation of new mesoionic systems. Thus carbon disulfide and phenyl isothiocyanate afford a zwitterionic thiazole and imidazole, respectively (Scheme 25). 

Another example which illustrates the importance of the structure of the diazoalkane in reactions of thiocarbonyl compounds and derivatives thereof is the reaction of trithiocarbonate S,S-dioxide 6 with diazomethane and phenyldiazomethane52. Whereas the former gives the dithiolane derivative 7, the latter affords the thiirane 8. Both reactions are, however, fully stereoselective affording single diastereomeric compounds the most probable structures are depicted in the scheme. 

Good yields of thietanes have been obtained by photolysis of a thiocarbonyl compound and an alkene. The thione is excited initially to one of two singlet states, Si (n -> 7T ) or Si (ir Thietane formation via the state proceeds through... 

Cycloaddition of a thiocarbonyl compound and a 1,3-diene affords a 5,6-dihydro-2//-thiapyran [Eq. (I)].1... 

In addition to activated olefins, other double-bond substrates, such as carbonyl and thiocarbonyl compounds and azomethines have been used ( ). Likewise, heterocumulenes, such as carbon disulfide, isocyanates, isothiocyanates, carbodiimides, and N-sulfinylamines have been added to nitrile imides ( ). While usually reaction occurs across one of the cumulative double bonds, with carbon disulfide only the bis-adduct LVIII could be isolated ( ). 

Esseffar et al. give an account of UV-visible spectra and intermolecular charge-transfer spectra of several complexes between thiocarbonyl compounds and I2 supplemented with ab initio calculations. A BCP between I and the amino H is localized demonstrating an intramolecular HB. They note that it appears between the iodine that points to the S atom, and not the terminal one as hypothesized before for imidazolidine-iodine complexes. 

LR converts carbonyl compounds to the corresponding thiocarbonyl compounds and alcohols to the corresponding thiols, as shown below ... 

The common method involves deprotonation of a thiocarbonyl compound and reaction of the intermediate enethiolate with an allyl halide (Scheme 9.8). This actually relies on two noticeable features of the sulfur series. (1) The proton located a to a thiocarbonyl group is much more acidic, by 7-10 pKa units, than the one of a carbonyl moiety [39, 41]. This may be related to the strong ability of the sulfur atom (polarizability) to stabilize the negative charge of the enethiolate. Presently, the preferred conditions involve LDA as a base for optimum deprotonation [42-45]. (2) The resulting anionic species are soft ambident nucleophiles. The... 

Thioamides and Related Compounds. Thioamides are the most stable thiocarbonyl compounds and have been prepared, for a century, from amides and P4S10 under rather drastic conditions. However, even for this purpose LR has turned out to be a superior reagent. High yields are obtained for all types of thioamides and -lactams including the elusive unsubstituted acrylo-thioamide (eq 18) and thioformamides or thioamides bearing sensitive substituents such as NO2, Z-NH, or OH (eq 19). ... 

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