Dithiocarbonyl

A series of 1,4-dithiocarbonyl piperazines has been synthesized from aldehydes, piperazine, and elemental sulfur under the action of microwave irradiation and solvent-free conditions. An important nonthermal effect of the radiation was revealed [72] (Eq. 19). 

The reaction of 1-alkynes 275 gives thioformylation products 277 (Equation (21)), " while that of propargyl alcohols 278 afforded thiofuranones 280 (Equation (22)). The reaction of allenes 281 gives alkenylthiolate 282 (Equation (23)), while dithiocarbonylation took place to yield 284 in the reaction of propargylic mesylates 283 (Equation (24)). ... 

Dithiocarbonyl azide see Azidodithiocarbonic acid and derivs 1 A632... 

Applied to dialkenyl disulfides, the dihetero sigmatropic shift gives rise to 1,4-dithiocarbonyl derivatives. The precursors are easily obtained by oxidation of the enethiolates, and the reaction has been observed with thioketones [500]. thioamides [501], dithioesters [356, 502] and thionesters [503],... 

The addition of lithium hydrosulfide to acetylene affords enethiol systems310 and the addition of elemental sulfur to diethylaminoacetylenes yields a-dithiocarbonyl compounds311,312 (equation 49). 

Dithiocarbonylated ethyl xanthates, (IV), dithiophosphorylates, (V), and azo derivatives, (VI), prepared by Wilczewska [2], Destarac [3], and Charmot [4], respectively, and were effective as chain transfer agents in free radical polymerization reactions. 

Overall, polymer chains with a dithiocarbonate end-group are formed. If addition to the dithiocarbonyl double bond is fast compared to propagation. 

One simple solution to this longstanding problem in radical chemistry is based on the degenerative radical exchange of dithiocarbonyl derivatives [3-6]. The principal, unwanted competing pathway is eliminated and, as a consequence, the intermediate radicals acquire a sufficient lifetime to allow them to add to un-activated olefins or, more generally, to undergo slow inter-or intra-molecular processes. 

There are many advantages attached to the use of the reversible addition-fragmentation on dithiocarbonyl derivatives. 

Dicyano-l,2-dithiete is an intermediate in the oxidation of the dianion of cis-2,3-dicyano-2,3-dimercaptoethylene 530 and related compounds.1,2-Dithietes are believed to be in equilibrium with 1,2-dithiocarbonyl compounds, as exemplified by 531. Several of these unstable 1,2-dithietes are observed by their electronic spectra at 77°K. Theoretical considerations indicate that the photochemical conversion of an a-dithione into a 1,2-dithiete is allowed the thermal process is forbidden. ... 

Dithiocarbonyl Azide. See Azidodithio-carbonic Acid and Derivatives, Vol 1, p A632-L... 

The mechanism involves the rearrangement of the intermediate into the l-5 -(5 -thio-/7-nitro-henzoyl)dithiocarbonyl glycopyranose followed by a subsequent rearrangement with loss of carbon oxide sulphide to give the product (compare O Scheme 40). 

Heating the diethanolamine or bis(2-chloroethyl)amine hydrochlorides with aniline derivatives gave 1-arylpiperazine derivatives. The 1-substituted piperazines were deuteromethylated. 1,4-Dithiocarbonyl piperazine was obtained from reaction of benzaldehyde with piperazine and sulfur. l,4-Diacetylpiperazine-2,5-dione were reacted with aldehydes to give the monoarylidene products and then 73. 4-Benzylpiperazine-2,5-dione was reacted with bromobenzene to give 74. Diels-Alder cycloaddition of pyrazinone with ethene gave 75 . ... 

The stability of the a-dithiocarbonyl compounds follows closely their potential utility for 4ir participation in Diels-Alder reactions with typical olefinic and acetylenic dienophiles [a-dithioamide > a-dithionoester > a-dithionothioester (dimer equilibrium at 25°C) > a-dithione > a-dithioalde-hyde]. The a-dithiocarbonyl compounds are electron-deficient and consequently react rapidly with electron-rich and strained olefins in inverse electron demand (LUMOd,ene controlled) Diels-Alder reactions and more slowly with unactivated or electron-deficient dienophiles in apparent normal (HOMODiels-Alder reactions (Scheme 8-IX).36 Subtle differences in the reactivity and observed course of reactions of the various a-dithiocarbonyl compounds have been detailed.36... 

The in situ photochemical generation of 1,2-dithioketones and -aldehydes including dithioglyoxal, 3,3-dimethyl-2-thioxobutanethial, and camphor dithioquinone was confirmed by the subsequent trap of the 1,2-dithiocarbonyl compounds in [4 + 2] cycloadditions. The 1,2-dithioketones and 1,2-dithioaldehydes exhibited a preference for 4ir participation in inverse electron demand (LUMOdlene controlled) Diels-Alder reactions with electron-rich dienophiles (Scheme 8-X).37... 

The reactivity of the thiocarbonyl group of 1,2-dithiocarbonyl compounds is well suited for 2n participation in Diels-Alder reactions with typical dienes (Chapter 5). In addition, frequent and well-defined Diels-Alder reactions with 4tt participation of symmetrical 1,2-dithiocarbonyl compounds with olefinic and acetylenic dienophiles have been detailed.36-39... 

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