Sulfide Lithium, 2- phenyl

Aryl sulfides are prepared by the reaction of aryl halides with thiols and thiophenol in DMSO[675,676] or by the use of phase-transfer catalysis[677]. The alkenyl sulfide 803 is obtained by the reaction of lithium phenyl sulfide (802) with an alkenyl bromide[678]. 

Thiol esters can be reduced to sulfides or aldehydes. Alone generated from lithium aluminum hydride and boron trifluoride etherate [1099] or aluminum chloride [1100] in ether reduced the carbonyl group to methylene and gave yi-9y /o yields of sulfides. Phenyl thiolbenzoate failed to give the sulfide, and phenyl thiolacetate gave only an 8% yield of ethyl phenyl sulfide [1100]. 

CYCLOBUTENES Cyclopropyl phenyl sulfide. Lithium aluminum hydride. 

KETENE THIOACETALS 2-Chloro-l,3-dithiane. phenyl sulfide. Lithium diisopropylamide. 

Commercially available, air-stable Pd phosphinous acid complex is an active catalyst for the thioether formation by the reaction of 1-cyclopentenyl chloride (49) with thiophenol (50) and hexylmercaptan (52) to give the thioethers 51 and 53 [15]. 1-Cyclopentenyl phenyl thioether (55) was obtained by the reaction of 1-cyclopentenyl triflate (54) with lithium phenyl sulfide [16]. 

The use of excess lithium LiDBB in reductive lithiations is a drawback for preparative-scale reactions. A modification of Yus procedure [72, 73] allowed for the generation of a-alkoxylithium reagents under catalytic conditions [45] (Scheme 35). Slow addition of the phenyl sulfide 185 to a suspension of lithium... 

Allylmetallic reagents The ally] anions obtained by reductive metallation of ally I phenyl sulfides with lithium l-(dimethy amino)naphthalenide (LDMAN, 10, 244) react with a, 3-enals to give mixtures of 1,2-adducts. The regioselectivity can be controlled by the metal counterion. Thus the allyllithium or the allyltitanium compound obtained from either 1 or 2 reacts with crotonaldehyde at the secondary terminus of the allylic system to give mainly the adduct 3. In contrast the allylcerium compound reacts at the primary terminus to form 4 as the major adduct. 

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 the extension of the above-mentioned stereoselective asymmetric addition of alkylithiums to other organolithium reagents such as lithium salts of methyl phenyl sulfide, 2-methylthiazoline, trialkylsilylacetylene, N-nitroso-dimethylamine, and acetonitrile, chiral oxiranes (95) U1), thiiranes (96) nl), acetylenic alcohols (98) 112), and amino alcohols (97) U1) were readily obtained. 

Analogs ofl-lithiocyclopropyl phenyl sulfide bearing a methylsulfanyl instead of a phenyl-sulfanyl group were obtained from dibromocyclopropanes by sequential treatment with butyl-lithium, dimethyl sulfide and butyllithium. Addition to aldehydes occurred readily and rearrangement of the resulting /7-hydroxy sulfides 10 with trifluoroacetic acid yielded cyclobutanones II.172... 

The cleavage of alkyl phenyl sulfides by naphthalenelithium or a lithium ... 

The treatment of the double bridgehead sulfide, l,3-bis(phenylthio)bicyclo[l.l.l]-pentane (15d), with lithium 4,4 -di-/-butylbi phenyl also induces reductive elimination and leads to [l.l.ljpropellane71. However, as the required bicyclo[l.l.l]pentanes 15 are most conveniently prepared from the corresponding propellanes, they do not really offer an alternative synthetic route to [1.1. IJpropellanes. They are best considered as convenient propellane storage materials37. 

The first step in the reductive lithiation of alkyl phenyl sulfides (Screttas-Cohen process) consists of preparing the reducing reagent in stoichiometric amounts. Lithium naphthalenide, for example, is made from lithium and naphthalene. The sulfide is added drop wise to this reducing reagent. The mechanism of reduction corresponds step by step to the one outlined in Figure 17.44, except that the dissolved radical anion is the source of the electrons, as opposed... 

When A.A-dimethylisoindolinium bromide is treated with phenyl-lithium, it gives V-methylisoindole via the ylid (54).2 59,60 An attempt to prepare benzo[c]thiophene via the analogous ylid (55) failed. Thus, when l,3-dihydrobenzo[c]thiophene methylsulfonium iodide was treated with phenyllithium, it gave a mixture of methyl phenyl sulfide, spiro[5.5]-l-methylthio-2,3-benzo-6-methylthio-methyleneundeca-7,9-diene (56), and 3,4-bis(methylthio)-l,2 5,6-dibenzo-l,5-cyclooctadiene (57).59,60 The formation of methyl phenyl sulfide may be explained by the formation and ring cleavage of compound 58, and compounds 56 and 57 arise by Diels-Alder dimerization of the o-quinodimethane (59) formed by ring cleavage of the ylid (55). 

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