Hexafluorothioacetone Research Articles

Regiochemistry of Diels-Alder reaction of hexafluorothioacetone and dienes

AbstractOK The reaction of 2,2,4,4-tetrakis(trifluoromethyl)-dithiethane-1,3 (1) with various hydrocarbon dienes is not regioselective and results in the formation of two isomeric Diels-Alder cycloadducts with the ortho isomer predominating. The reaction of non-conjugated dienes involves ene-insertion of hexafluorothioacetone (HFTA), followed by Diels-Alder reaction of the product of the ene- reaction with a second mole of HFTA, while the reaction of 1,1,4,4-tetramethylbutadiene-1,3 and 2,5-dimethylhexadiene-1,5 results exclusively in HFTA insertion into the allylic C H bond.

Do reactions of 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane require fluoride anion catalysis?

Abstract 2,2,4,4-Tetrakis(trifluoromethyl)-1,3-dithietane (cyclic dimer of hexafluorothioacetone (1)) was shown to react with a variety of organic substrates in the absence of metal fluoride catalyst at elevated temperature in DMSO or DMF solvents. While the reactions of vinyl ethers, phenyl vinyl sulfide, dienes and anthracenes under these conditions led to the formation of expected cycloadducts, the reaction of 1,5-cyclooctadiene resulted in the formation of the product derived from an ene reaction with hexafluorothioacetone (HFTA). In contrast to results reported for the CsF catalysed process, 2-vinylnaphthalene reacted with 1 to produce a compound that resulted from reaction with two molecules of HFTA. The structure of this adduct was established using single crystal X-ray diffraction. The formation of similar products was also observed in non-catalysed reactions of styrene and 2-methylstyrene with 1. Interestingly, no product of this type was observed in reaction of 4-MeO-styrene with 1, which instead led to the high yield formation of the corresponding thietane. The reaction of 1 with 1,3-cyclohexadiene was carried out in various organic solvents: the reaction in DMSO and DMF was significantly faster than in acetonitrile, tetrahydrofurane or hexane.

Hexafluorothioacetone‐Based Synthesis of Fluorinated Heterocycles.

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Hexafluorothioacetone based synthesis of fluorinated heterocycles

Cycloadducts of hexafluorothioacetone (HFTA) were prepared in high yield by a CsF catalyzed reaction between readily available 2,2,4,4-tetrakis-(trifluoromethyl)-1,3-dithietane (as a source of HFTA) with conjugated electron-rich hydrocarbon dienes, such as cyclopentadiene, 2,3-dimethylbuta-1,3-diene, cyclohexa-1,3-diene or (1 Z,3 Z)-cyclohepta-1,3-diene. Cyclohexa-1,4- and (1 Z,5 Z)-cycloocta-1,5-dienes, also undergo the reaction with in situ generated HFTA, but form the products of insertion of HFTA into the C–H bond of the diene as a result of ene-reaction. The highly selective reaction of HFTA with (1 Z,3 Z,5 Z)-cyclohepta-1,3,5-triene and (1 Z,3 Z,5 Z,7 Z)-cycloocta-1,3,5,7-tetraene leads to the formation of cycloadducts derived from exclusive addition of thioacetone to the corresponding bicyclic isomers—bicyclo[4.1.0]hepta-2,4-diene or bicyclo[4.2.0]octa-2,4,7-triene, respectively. The corresponding cycloadducts of HFTA with 2,3-dimethylbutadiene-1,3-cyclohexa-1,3-cyclohexa-1,4-dienes and (1 Z,3 Z,5 Z)-cyclohepta-1,3,5-triene were also prepared by direct reaction of sulfur/hexafluoropropene/KF and the corresponding hydrocarbon substrate at 35–45 °C in DMF.

Die reaktion von dithiooxamid mit dimerem hexafluorthioaceton

Dimeric hexafluorothioacetone (HFTA) ( 1) reacts with dithio-oxamide( 2) to give two isomeric products 3a and 3b. Theequilibrium of the two isomers has been studied by 1H- and 19F-nmrspectroscopy. The structure of 3a has been determined by X-raycrystallography.