Thioketenes synthesis

Schaumann. E.. and Grabley, EE, Thioketene synthesis. Part 3. Reactions of phosphonate carbanions with carbon disulfide, Liebigs Ann. Chem., 1715, 1979. 

Ketenes and related compounds have been reviewed extensively (1 9). For the synthesis and synthetic uses of conjugated ketenes see Reference 10. Ketenes with three or more cumulated double bonds have been prepared (11,12). The best known is carbon suboxide [504-64-3] 3 2 preparative uses and has been reviewed (13—16). Thioketenes (17,18), ketenimines (19—21), and their dimers show interesting reactivity, but they have not achieved iadustrial importance to date. 

Thio-Claisen rearrangement 746-748 Thioketene 5-oxides photolysis of 878 reactions of 277 Thiolane dioxides formula of 382 NMR spectra of 460 reactions of 604 synthesis of 461 Thiolane oxides 747 formula of 382 IR spectra of 461 synthesis of 461, 462, 752 Thiolanes, photolysis of 881 Thiolene dioxides formula of 382 NMR spectra of 460 reactions of 464, 465 synthesis of 461 Thiolene oxides formula of 382 synthesis of 461, 746 Thiols... 

Vallee Y., Ripoll J. L. Synthesis of Thioaldehydes, Thioketones and Thioketenes... 

The synthesis of 2-alkylidene-l,3,4-thiadiazolines from thioketene and diazo compounds was discussed in the photochemical Section 4.10.6.1 <90TL357i>. 

As for thioaldehydes, the stability of thioketenes is largely influenced by the nature of the substituents and bulky groups tend to stabilize this functional group. Electronic factors such as those originating in silicon, phosphorus or trifluoromethyl substituents lead to a similar result. In general, however, the synthesis of monomeric thioketenes is difficult and requires the use of special techniques such as FVT, matrix isolation at low temperatures or generation under conditions which allow trapping in situ of the transient species. The... 

The versatility and selectivity of the Lawesson reagent is also evidenced in the synthesis of the highly complex alkaloid 19-hydroxytubotaiwine287, in which a ketolactam is transformed into a thionethiolactam (equation 41). Also, Diels-Alder cycloadducts can be thionated with 52 and, upon thermolysis at high temperatures (FVT), afford the corresponding thioketenes which are trapped in situ2m (equation 42). 

Only one isolated example of formation of thioketene and thioaldehyde dimolybdenum complexes has been reported507, but in contrast, zirconocene thioacetaldehyde and thiobenzaldehyde complexes, introduced by Buchwald, have been the subject of several studies508, including their application in the synthesis of novel antimony thiametallacy-cles 148509 (equation 156). Compound 146 was generated in situ and, after reaction with alkynes, gave rise to metallacycles 147 which, by treatment with SbCR, afforded 148. 

The synthesis of poly-dibenzylidene-l,3-dithietane 201 is based on the Wittig reaction of/ -xylcnc-bis(triphcnyl-phosphonium) chloride 199 with carbon disulfide <2001MM346, 2002MM3806>. The phosphonium salt 199 was converted to the ylide 200, which reacted with carbon disulfide, yielding, after methanolysis, a thioketene. The latter was stirred at room temperature for 12 h to provide the polymeric compound 201, bearing 1,3-dithietane moieties in 54% yield (Scheme 25) <2001MM346, 2002MM3806>. 

SCHEME 111. Synthesis of y-lactones from tartaric-derivedbis-thioester by aldol reaction and the bis-thioketene acetal obtained by silylation of the intermediate bis-enolate552... 

A general synthesis of benzofuran-2-thiolates utilizes 1,2,3-thiadiazoles as cyclization precursors. Upon treatment with base, the heterocycle is deprotonated and extrudes nitrogen to generate an alkynethiolate which can be spectroscopically monitored. This species can take up a proton to form a thioketene that undergoes cyclization to a benzofuranthiolate which is finally alkylated with an alkyl halide (Equation 125) <1997CC1753>. 

Thioketenes, for example, 463, add to imines, carbodiimides, and azines to give 1,3-thiazetidines with exocyclic double bonds, as exemplified by the synthesis of 464. A novel ring contraction of 464a gives 1,3-thiazetidine 464b. 1,3-Thiazetidlnes are postulated as intermediates in the photochemical addition of thiobenzophenone to imines. They fragment to the two possible thiocarbonyl components and imines. ... 

The formation of desaurins from ketones, carbon disulfide, and base 1275,1281,1282,1285-1290 believed to involve nucleophilic attack on a thioketene by the dianion of a 1,1-dimercaptoalkene, as shown for the synthesis of 572. Related syntheses involve the use of thiophosgene instead of carbon disulfide and the use of diazoalkanes or phosphonium and sulfonium ylides instead of a ketone and base. Treatment of perfluoroiso-butylene with fluoride ion and elemental sulfur in a dipolar, aprotic solvent ° °° or with sources of anionic sulfur (potassium sulfide, sodium hydrosulfide,potassium thiocyanate,sodium thiosulfate, dithiocarbamate salts, dithiophosphate salts ) give the dimer (573) of bis(trifIuoromethyl)-thioketene. Similarly, other 2,4-bis(methylene)-l,4-dithietanes are obtained by treating 2,2-dichlorovinyl ketones with anionic sulfur re-... 

Treatment of desaurin 572 with P4S10 leads to extensive rearrangement with incorporation of additional sulfur atoms in the products.The synthesis of the important dimer of bis(trifluoromethyl)thioketene 573 involves treating the tetra-ester 586 with Depending on conditions, two, three or... 

Thioketenes (34) are highly electrophilic and give a smooth reaction with ammonia or amines. In fact, addition of a secondary amine offers the best way to scavenge a suspected thioketene. But the approach also deserves interest from the point of view of thioamide synthesis as it allows very mild and nonreducing conditions, tolerating the presence of sensitive additional functional groups such as cyano, nitro, or sulfonyl residues (equation... 

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