Thioketones thiol

The addition of H2S to an aldehyde or ketone can result in a variety of products. The most usual product is the trithiane (8). ° ot-Hydroxy thiols (5) can be prepared from polychloro and polyfluoro aldehydes and ketones.Apparently, compounds 5 are stable only when prepared from these compounds, and not even for all of them. Thioketones (6) can be prepared from certain ketones, such as diaryl ketones, by treatment with H2S and an acid catalyst, usually HCl. They are often unstable and tend to trimerize (to 8) or to react with air. Thioaldehydes are even less stable and simple ones apparently have never been isolated, though t-BuCHS has been... 

Like its monomeric counterpart, the polymeric reagent is inert to simple amines, amides, alcohols and phenols, but easily oxidizes thiols to disulphides, phosphines to phosphine oxides, hydroquinone and catechol to quinones, and thioketones, thioesters and trithiocar-bonates to the corresponding 0x0 derivatives, in dichloromethane, chloroform or acetic... 

Perfluorohalogenoorganosulfenyl halides are, like thiols, mercaptides, and thioketones, key compounds for the synthesis of new perfluorohalo-genoorganomercapto derivatives. The high reactivity of the S—X bond (X = Cl, Br) toward electrophilic as well as nucleophilic reagents causes them to be highly valued starting materials for the synthesis of new derivatives. The chemistry of the not very stable sulfenyl fluorides has... 

However, for the free acid "C NMR analysis indicates the presence of a thioketone function instead of a thiol function <77JHCI4I7> (see Section 4.19.3.2). 

When a,/3-unsaturated esters are the target molecules, the use of a thioaldehyde or thioketone is advisable for the easy elimination of H2S from the intermediate thiol adduct. This strategy has been applied to thiolactams 94a and to thionolactones 94b, opening a route to vinylogous carbamates 95a143 and carbonates 95b144(equation 57). 

The reactions of dinuclear thioaldehyde and -ketone complexes with PR3 take a different course. When the dimeric complexes 112 are treated with PMe3 a Ti-S bond in 112 is cleaved and the monomeric complexes 113 are reversibly formed (see Scheme 26), 69 The reaction of 112 with benzene-thiol led to a Ti-C cleavage and formation of 1,3-propanedithiolato-(phenylthiolato) complex.69 The reaction of binuclear p-191 rf-thioketone molybdenum complexes related to 115 (M = Mo, E = S, R = Aryl) with P(OEt)3 also gave mononuclear complexes [Mo(CO)2(Et) i72-S = C(Aryl)2 (i75-C5H5)] by a rather complicated reaction sequence. When other phosphites were employed additionally binuclear complexes derived from addition of the phosphite to one molybdenum atom were isolated.225... 

Baker s yeast has been used to reduce selectively the thioketone moiety in a /J-thioketo ester353. Whilst a mixture of alcohol and thiol containing products are obtained, the ee is... 

Reduction of diaryl thioketones with ytterbium metal affords a mixture of the corresponding thiols and diarylmethanes together with products arising from homocoupling reactions (equation 119)433. 

The following reactions proceed with the participation of the allylic boron system (i) allylboration and protolytic cleavage of organic compounds with multiple bonds, (ii) allylboron-alkyne condensation,598 599 (iii) reductive mono-and trans-a,a -diallylation of nitrogen aromatic compounds, (iv) disproportionation processes between tribut-2-enylborane and BX3 (X = C1, Br, OR, SR). Allylboration of carbonyl compounds, thioketones, imines, or nitriles leads to the homoallylic alcohols, thiols, or amines (Equations (136) and (137). It is most important that 1,2-addition to aldehydes and imines proceeds with high diastereoselectivity so that ( )-allylic boranes and boronates give the anti-products, while -products are formed preferentially from (Z)-isomers. 

These tellurium-containing polymers were checked for their catalytic activity in the ep-oxidation of olefins1 and as oxidizing agents2. The polymeric 4-methoxyphenyl tellurium oxide did not react with amines, amides, alcohols, or phenols, but oxidized hydroquin-ones to quinones, thiols to disulfides, thioketones to ketones, thioesters to esters, and thiobenzamides in organic solvents to cyanobenzenes and in acetic acid to 2,5-diaryl-4,l,3-thiadiazoles2. 

There is apparently only one report of the dissolving metal reduction of thioketones thiobenzophe-none (107) has been reduced with excess Na-THF to give dianion (108), which on acidification gave thiol (109). The thiol was not isolated, but was oxidized with iodine to give the corresponding disulfide in 65% overall yield. The mechanism of the reduction is suggested to be the sequential addition of two electrons to the thiocarbonyl, which was confirmed by electron spin resonance spectroscopy studies of the intermediate thioketyl, and trapping dianion (108) with a variety of electrophiles. ... 

Thioketones (6) are slowly oxidised in air to the corresponding ketones, and they are reduced by the majority of common reducing agents to the thiols (29). Sodium borohydride often gives the optimum yield of the thiol. On the other hand, reduction with zinc-hydrochloric acid affords the hydrocarbon (30) the latter reaction is analogous to the Clemmensen reduction of ketones (Scheme 17). 

The most obvious disconnection (1,1-diX) of a thiazole 43 reveals an acid derivative but the other starting material 44 is an impossible compound requiring NH2 and SH groups to be cis substituted on an alkene. Neither of these functional groups (primary enamine or thioenol) is stable and control of the geometry would also be impossible. The thiol 44 is also the thioenol of an a-amino thioketone 45 these are equally unknown. 

Ring opening of 1,2-epoxides with thiol-derived nucleophiles is a well established route to /3-hydroxy sulfides that has been applied for the preparation of allylic alcohols, cyclic sulfides, thioketones, and important intermediates for the synthesis of... 

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