Methyllithium dichloride

However, the reaction of (lZ,3Z)-l,4-dilithio-l,3-butadiene (36) with phenylantimony dichloride (Scheme 5) affords 1-phenylstibole (37),14 which has been converted to l.l -distibaferrocene (9).15 Unfortunately, there is no totally satisfactory synthetic route to dilithio compound 36. Sn/Li exchange of (lZ,3Z)-l,4-bis(trimethylstannyl)-l,3-butadiene (38) with methyllithium gives a good yield of 36, but the preparation of 38 is... 

Very recently, Eisch and co-workers have developed new alkylidene-group IV metal complexes such as methylidene titanium dichloride 67, readily accessible from titanium(iv) chloride and an excess of methyllithium at low temperature (Scheme 24).53 The new methylenating agent 67 can easily convert benzophenone at low temperature into 1,1-diphenylethylene in quantitative yield. 

The Petasis reagent, dimethyl titanocene (4.93) can also be used for the methylenation of carbonyl compounds. The Petasis reagent (4.93) is prepared by the reaction of methyl magnesium chloride or methyllithium with titanocene dichloride (Cp2TiCl2). Carbonyl compounds on heating with 4.93 at 60-65° C in a toluene solution give the corresponding alkenes or enol ethers. 

N-Methylisatin, 228 Methyl isobutyl ketone, 87 Methyl isocyanate, 341 Methyl isocyanide, 272 Methylisocyanide dichloride, 5 23 Methyl jasmonate, 483-4 84 Methyl 3-keto-l-cyclohexaneacetate, 396 Methyl 6-ketoheptanoate, 108 Methyl levopimaiate, 149 Methyllithium 36, 151, 214, 310, 334, 337, 407... 

Insertion with complete regio- and stereoselectivity occurs when steroids 2 are treated with methyllithium to give 3 the Cl 1 to HI la bond is exclusively attacked by the cyclopropylidene intermediate. The clean reaction with the dichloride is noteworthy. 

Pentamethylbismuth is prepared from trimethylbismuth dichloride and methyllithium [94AG(E)976]. Pentaorganylbismuth compounds can be transformed into lithium hexaorganylbismuthates by further action of organo-lithium reagent [93IC3948, 94AG(E)976]. 

Wittig and Clauss499 obtained pentaphenylarsenic by the action of phenyl lithium on triphenylarsine dichloride or tetraphenylarsonium bromide. The analogous reaction of methyllithium with trimethylarsine dibromide or tetra-methylarsonium iodide gave no isolable amount of pentamethylarsine, although the formation of small amounts of this product could be demonstrated among the others.500... 

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. 

More recently, Petasis has shown that titanocene dimethyl, " which is easily generated from titanocene dichloride and methyllithium, also generates the same titanium methylidene upon thermolysis (Scheme 13.5, bottom). Thermolysis of titanocene dimethyl is a convenient way to generate the titanocene-methylidene complex because titanocene dimethyl is formed in high yield and is stable to water, -although it is sensitive to light and can undergo autocatalytic decomposition. This complex has been used in synthesis... 

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