Sulfides thio esters

Thiols and sulfides are protonated on sulfur in superacid media and give mono- and dialkylsulfonium ions, respectively49. Thiocarboxylic acids, S-alkyl esters, thio-esters, dithioesters and thiocarbonates in similar media also form stable protonated ions179 such as... 

Petasis and co-worker reported that methylenation of selenol and thio esters with dimethyl titanocene led to the formation of the corresponding vinyl se-lenides and sulfides (Eq. 58) [111]. Dimethyl titanocene can be easily prepared from titanocene dichloride and methyllithium [112]. The methylenation reactions involve simply heating a mixture of dimethyl titanocene and chalcogeno esters at 60-75 °C. 

Leeks Leek oil contains numerous thiols, sulfides, di-, tri-, tetra-, and pentasulfides, trithiolanes and thio-esters. One isomer of 3-ethyl-5-methyl-I,2,4-trithio-lane (CsH.oSj, Mr 166.31, CAS [116505-59-0]) has a mild leek odor, the other resembles the odor of onions. S-S... 

Sulfides orthio derivatives Metallic derivatives of thio ethers and disulfides, usually mixed with organic phosphite esters long-chain alkyl thienyl ketones Lubricating oils boiler water... 

Further adaptations of the boranes has led to reagents which reduce carboxylic acids but afford thio-acetals rather than the aldehyde itself.Thus, with the thioborane (3 equation 1), aliphatic acids give 80-87% yields of thioacetals but aromatic acids respond less well in giving significant quantities of sulfides as well. Carboxylic acid esters are inert to this reagent but give sulfides if a Lewis acid is included. Similarly, the 1,3,2-dithiaborinane-dimethyl sulfide adduct (4 equation 2) affords cyclic dithioacetals in 70-90% isolated yields in the presence of SnCb. Aliphatic acids react in about 6 h at room temperature but aromatic acids need about 20 h and yields are somewhat poorer. This area has been reviewed.From a practical viewpoint, it should be noted that the dithiaborinane (4) requires a week for its preparation. 

Also shown in the same equation is the synthesis of esters by the reaction of 3-pyrazolin-5-ones with carbon disulfide and either ethyl bromide or ethyl chloroformate in the presence of aluminum chloride.89,109 The monothio acids have been synthesized by reaction of acid chlorides with hydrogen sulfide.109 Kocwa826,829,830,831 has studied the preparation of amides and hydrazides of these thio acids and found that two types exist. In one type the compounds are thioamides but in the other they are iminothiolic acids. Treatment... 

Although the corresponding thio compounds should be readily available from hydrazidoyl halides and hydrogen sulfide or mercaptans, respectively, these reactions are not reported in the literature. However, Fusco and Musante investigated the reaction of thiocarbonic acid 0-esters with hydrazidoyl bromides. 

Acetates of MBH adducts have also been established for the synthesis of sulfur-containing trisubstituted alkenes via a nucleophilic displacement protocol, in either S- 2 or S- 2 fashion with 5-centered nucleophiles, such as thio-lates, ° arenesulfinate and thiocyanate anions. Significantly, these reactions are highly stereoselective for both acrylonitrile/acrylate ester-derived MBH acetates, but with a reversed stereochemical directive effect, that is, acrylonitrile-derived MBH acetates afford ( )-sulfur-containing trisubstituted alkenes 336 as the sole product, while acrylate ester-derived MBH acetates afford (Z)-olefins 335 exclusively under the same reaction conditions. Both (Z)-and ( )-allyl sulfides have been stereoselectively obtained from MBH acetates in a one-pot with treatment with benzenethiol in the presence of catalytic amounts of 15% aqueous NaOH and TBAI in DM SO at room temperature (Scheme 3.146). ° The method has also been applied for the synthesis of (Z)-3-(4-methoxybenzylidene)thiochroman-4-one (337), a potent antifungal compound (Scheme 3.147). 

---