Thioketene 5-oxides

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... 

Thioketenes react with diazo compounds in the presence of metal catalyst ([Rh(OAc)2]2, CuCl, or CuS04) to yield the corresponding allene episulfides <81T219>. Allene episulfide 5-oxide can be formed from thioketene 5-oxide and diazo compounds <88T1827>. 

Other thermal 1,3-dipolar cycloadditions are the reactions between nitrile sulfides and electron-deficient aldehydes and ketones forming 1,3,4-oxathiazolines (98 Scheme 19) between aryl thioketones and thiofluorenone 5-tosylimide to yield the 1,3,4-dithiazolidines (204) and between thioketene 5-oxides and imines, yielding in one case the 1,2,4-oxathiazolidine (136). 

The azo-compound (248) rearranges thermally to the pyrazole (249). The 1-pyrazoline (250) is formed from the thioketen 5-oxide Bu Pr C=C=SO and 2-diazopropane.The allyl chloride H2C=C(COPh)CH2Cl reacts with 1,1-dimethylhydrazine to yield the pyrazolidine derivative (251). Numerous betaines (252 R, R, R = H or Me) have been prepared by the action of aromatic aldehydes on the appropriate pyrazolidinones. Treatment of diethyl acetylmalonate with 1,1-dimethylhydrazine affords the amine-imide (253). ... 

High-level quantum-chemical calculations on the 3 + 2-cycloadditions of thioformaldehyde 5 -imides, S -methylide, S-oxide, and 5-sulfide have been reviewed. Theoretical studies on the 1,3-dipolar cycloaddition between thioketene 5-oxide and methyleneimine show that this reaction is concerted but non-synchronous. Adamantanethione 5-methylide reacts with thiocarbonyl compounds to produce 1,3-dithiolanes. A density-functional-theory study of the cycloaddition of the sulfine H2CSO predicts the 2 + 3-mechanism having the lowest pathway, with an activation barrier of 12.3kcalmoP. R The thermal and photochemical reactions of fluorenethione 5-oxide (69) with cyclooctyne (70) involves an initial 1,3-dipolar cycloaddition to produce the adduct (71), followed by an efficient sulfur transfer to cyclooctyne to produce the enone (72) and the dithiin (73) (Scheme 26). ° ... 

Thioketene 5-oxides, which are sulfines with an extended cumulenic system, also participate in the cycloaddition reaction with 2-diazopropane. In this case, exclusive reaction across the C=C bond is observed to form the cycloadduct 29 in 70 % yield. ... 

In contrast, thioketene 5-oxides react with azomethines via a [3-1-2] cycloaddition in which the C=S=0 group participates as a 1,3-dipol to give SO". ... 

Oxidation of thioketenes with peracids affords thioketene 5 -oxides (R2C=C=S=0) , a class of heterocumulenes also treated in this chapter. A review of thioketene -oxides was published in 1985. Also, alkylidenethioketenes (R2C=C=C=S) and thiocarbonyl-5 -sulfides (R2C=S=S) are known. The higher homologue, CH2=C=C=C=S, is generated by irradiation of matrix isolated 2,5-diiodothiophene. ... 

An unusual reaction of thioketen 5-oxides with azomethines leads to 1,2,4-oxathiazolidines, a representative of the still largely unknown cyclic esters of sulphenic acid (Scheme 39). The structure has been confirmed by AT-ray analysis. ... 

Thioketene -oxides are excellent 1,3-dipoles. For example, reaction with azomethines proceeds via a [3+2] cycloaddition to give the oxazolidinethiones 69 in 48-72 % yields The cycloadducts 68 readily rearrange to give 69. 

When the thioketene -oxide 70 is reacted with the Lawesson Reagent, an isolable thiirane 2-thione 71 is obtained, which is also an excellent 1,3-dipole because a quantitative yield of the cycloadduct 72 is obtained on reaction with dimethyl acetylenedicarboxylate. ... 

In the reaction of thioketene -oxides with diazo compounds also [3+2] cycloadducts 75 are obtained in 13-95 % yields. ... 

Also, a [3+2] cycloaddition reaction of thioketene -oxides with 2-azaallyl anions 76 affords ionic cycloadducts, which after acidification give the heterocycle 77 . 

Thiirenes are photochemically converted to thioketenes or to alkynylthiols (Scheme 22) (80PAC1623). 2-Acetyl-3-methylthiirene rearranges on irradiation at 310 nm to a mixture of acetylmethylthioketene and thioacetylmethylketene, identified by their IR spectra (80NJC703). 2,3-Diphenylthiirene 1-oxide at 130 °C is believed to be isomerized to monothiobenzil which is air-oxidized to benzil (Scheme 23) (79JA390). 

Thiirenes have been isolated in argon matrices at 8 K by photolysis of 1,2,3-thiadiazoles or vinylene trithiocarbonates (Scheme 151) (80PAC1623, 8UA486). They are highly reactive and decompose to thioketenes and alkynes (Scheme 22). Electron withdrawing substituents stabilize thiirenes somewhat, but no known thiirene is stable at room temperature unlike the relatively stable thiirene 1-oxides and thiirene 1,1-dioxides. 

In an interesting contrast to the photochemical behavior of the simpler sulfine system, the photolysis of thioketene S-oxides such as 25 in carbon tetrachloride leads to the corresponding thioketenes in excellent yield36. This photochemical deoxygenation is... 

A -1,3,4-Thiadiazoline-1 -oxides (146) (Equation (18)) are formed by addition of diazo compounds (R2C=N2) to sulfines (R R C =S=0). The adducts from diazomethane and aryl substituted sulfines are unstable and give the thiadiazole (147) via a Pummerer-type aromatization <84CHEC-I(4)545>. The A -thiadiazoline-1,1-dioxide (149) has been produced by oxidation of the hydrazone (148) (Equation (19)) and treatment with sulfur dioxide <84CHEC-i(4)545>. 2-Alkylidenethiadiazolines can be obtained from the dipolar addition of diazo compounds to thioketenes <83CB66, 90TL3571, 92HCA1825>. 

Cycloaddition with thioketenes 3-Substituted imidazole 1-oxides 228 react with thioketenes to give a mixture of l,3-dihydro-2H-imidazol-... 

There is a long standing interest in the chemistry and the properties of cyclic compounds containing sulfur atom in modern material chemistry due to their redox chemistry. In particular, the focus has been on dithiole derivatives, e.g., dithiafulvenes and tetrathiafulvalenes, since the finding of metallic conductivity and low temperature superconductivity in radical cation salts. The quite low oxidation potentials of 1,4-dithiin compounds have been reported, recently [109]. On the other hand, thioketene dimers (2,4-bis(alkyli-dene)-l,3-dithietane) have been known for more than 100 years and synthesized by various methods [110-115]. The structure of these dimer compounds is similar to that of the redox-active sulfur compounds therefore, the potential electronic property of the thioketene dimer moiety is considerably attractive with the aim of application to a new and better -donor. 

We have reported the first electroactivity of a thioketene dimer compound [116]. The CV measurement of 2,4-dibenzylidene-l,3-dithietane (31), which was prepared by a basic dimerization of phenylthioketene derived from ben-zyltriphenylphosphonium chloride, showed irreversible two-step oxidation peaks at 0.25 and 0.61 V vs Ag/Ag+, indicating that 31 acts as a stronger electron donor than 2,6-bisphenyl-l,4-dithiafulvene (30) and TTF (2). The dimer (31) can form a 1 1 CT complex with TCNQ in DMSO. Cycloaddition polymerization of bisthioketene derived from p-xylenebis(triphenylphosphoni-um chloride) gave a -conjugated polymer (32) with thioketene dimer unit in the main chain (Scheme 12). This polymer was the first polymer contain-... 

Thioketen tert.-Butyl-isopropyl- -S-oxid Ell, 942 (S-Oxigenier.)... 

Reaction of l-benzyM,5-dimethylimidazole 3-oxide 362 with thioketene 363 in CDCI3 at room temperature for 2h gave a mixture of deoxygenated imidazole 364 as well as imidazole-2(3//)-thione 365 in 84% and 15% yields, respectively. Thiiranone 366 and ketene 367 were also obtained in 70% and 14% yield, respectively (Equation 54) <1998HCA1585>. 

Acetyl groups in desaurins may be oxidized to carboxylic acid groups by sodium hypochlorite without affecting the basic bis(methylene)dithietane structure. Treatment of 575 with bromine in chloroform effects replacement of the two methine hydrogen atoms by bromine atoms.An unusual methylene-1,3-dithietane reacts with bis(trifluoromethyl)thioketene to give a complex structure embodying a new methylene-l,3-dithietane and a 2-methylenethietane. Bis-... 

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