Lithium sulfide intermediate compounds

The second step is also heterogeneous and involves the breakdown of the intermediate compound with further lithiation into lithium sulfide [12136-58-2] and finely divided iron [7439-89-6] particles. 

Vinyllithium [917-57-7] can be formed direcdy from vinyl chloride by means of a lithium [7439-93-2] dispersion containing 2 wt % sodium [7440-23-5] at 0—10°C. This compound is a reactive intermediate for the formation of vinyl alcohols from aldehydes, vinyl ketones from organic acids, vinyl sulfides from disulfides, and monosubstituted alkenes from organic halides. It can also be converted to vinylcopper [37616-22-1] or divinylcopper lithium [22903-99-7], which can then be used to introduce a vinyl group stereoselectively into a variety of a, P-unsaturated systems (26), or simply add a vinyl group to other a, P-unsaturated compounds to give y, 5-unsaturated compounds. Vinyllithium reagents can also be converted to secondary alcohols with trialkylb o r ane s. 

Tertiary and aromatic nitroso compounds are not readily accessible consequently not many reductions have been tried. Nitrosobenzene was converted to azobenzene by lithium aluminum hydride (yield 69%) [592], and o-nitrosobiphenyl to carbazole, probably via a hydroxylamino intermediate, by treatment with triphenylphosphine or triethyl phosphite (yields 69% and 76%, respectively) [298]. Nitrosothymol was transformed to amino-thymol with ammonium sulfide (yield 73-80%) [245], and a-nitroso-/J-naphthol to a-amino-/J-naphthol with sodium hydrosulfite (yield 66-74%) [255]. 

The classical preparation of alkyllithium compounds by reductive cleavage of alkyl phenyl sulfides with lithium naphthalene (stoichiometric version) was also carried out with the same electron carrier but under catalytic conditions (1-8%). When secondary alkyl phenyl sulfides 73 were allowed to react with lithium and a catalytic amount of naphthalene (8%) in THF at —40°C, secondary alkyllithium intermediates 74 were formed, which finally reacted successively with carbon dioxide and water, giving the expected carboxylic acids 75 (Scheme 30) °. 

By oxidising the sulfide to a sulfone, the synthetic versatility of this class of compounds is further increased. Deprotonation of either or both diastereoisomers of 98 leads, under thermodynamic control, to the equatorial organolithium 101 in which a destabilising interaction between the oxygen lone pair and the lithio substituent is avoided. However, lithium-naphthalene reduction of 102 to the organolithium 103 is axially selective because of the stabilisation afforded to the intermediate radical by the axial lone pair. Protonation of the product gives 104.88... 

Peterson (24) has also shown that even dimethyl sulfide can be metalated by BuLi-TMEDA to give high yields of methylthiomethyl-lithium. The reaction is rapid at room temperature and essentially complete within four hours in hexane as the solvent. Methylthiomethyllithium is quite valuable as an intermediate in synthesizing carbon functionally substituted organosulfur compounds since it has the unique advantage of giving derivatives in the sulfide oxidation state. These derivatives can... 

The potassio intermediates give excellent results in a number of derivatizations. For other functionalizations, particularly those with carbonyl compounds, potassium has to be replaced by lithium, this can be done most simply by addition of an equivalent amount of anhydrous lithium bromide, dissolved in THF. Although both vinyl ethers and the corresponding sulfides can be metallated in a short time, it is quite clear from the preparative experiments that the sulfides react faster [9]. A similar difference between oxygen and sulfur compounds has been observed in retaliations of other types of substrates. Some authors have invoked d-orbital effects to explain the easier retaliations of sulfur compounds [83], but an explanation on the basis of polarizability seems more satisfactory [84]. Using the kinetically very active bases mentioned, clean a-metallations of simple vinylic ethers and -thioethers can be realized at low temperatures. Under modified conditions two other processes have been observed [9,85] ... 

Lithium intermediates served as the starting compounds in the synthesis of the corresponding 2(a)- or 3(p)-substituted derivatives of thienyl sulfides 153 and 154, thieno[2,3-Z)]thienyl sulfides 155 and 156 and thieno[2,3-Z)]thienylthieno[2,3-Z)]thio-phenes 157 and 158 (79BSB325). 

Bruckner s approach started from L-arabinose converted in five steps to allylic alcohol 175, and to alkoxy sulfone 176 thereafter (Scheme 23). Key [2, 3] Wittig rearrangement of lithiated 176 in the presence of allyl lithium led to the desired compound 178 and its C17 isomer (ratio 1.4 1) via the intermediate 177. Regioselective epoxidation and thiophenate epoxide ring opening furnished sulfide 179 transformed in four steps to the C14-C20 building block 180. 

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