With methyllithium to give

Unsubstituted oxepin reacts with methyllithium to give ew-6-methylcyclohexa-2,4-dien-l-ol216 and traces of the /runs-product,12 whereas the reaction with dimethylmagnesium gives a mixture of cis- and /rani-isomers in a ratio of 37 63.216 By using deuterated starting material it has been shown that a 1,6-addition takes place.216,217... 

Camphor tosylhydrazone, with methyllithium to give 2-bor-nene, 51, 66... 

The a-arylamino nitriles 251, obtained from primary aromatic amines, trimethylsilyl cyanide and acetone in the presence of zinc chloride, react with methyllithium to give A-t-butylarylamines 252287. Af,Af-Bis(trimethylsilyl)amines 253 (R = allyl, benzyl, 3-phenylpropyl etc.) are formed in 50-88% yields by the action of chlorotrimethylsilane on primary amines in the presence of a catalytic amount of titanium(IV) chloride288. 

Tosylhydrazones, formation, 52,122 with methyllithium to give olefins, 51, 69... 

Optical resolution employing a chiral Pt(II) complex enabled them to obtain (—)-l,2-cyclononadiene (the enantiomer of 116), [a] —71° (neat) which was estimated to have an optical purity of 44%. In their second approach, (—)-(R)-( )-cyclooctene (6) was treated with dibromocarbene to yield the ( + )-adduct 115, which was further treated with methyllithium to give (+)-116, [[Pg.19]

Smaller cyclic olefins react with dibromocarbene to give the gem-dibromo-bicyclic systems, but these have not been reported to give allenes on reaction with methyl- or n-butyllithium. One possible reason may be the severe ring strain of cyclic allenes with less than seven carbon atoms. For example, Moore and Ward [14] found that 7,7-dibromobicyclo[4.1.0]heptane reacts with methyllithium to give bicyclic carbene intermediates which can be trapped with olefins (Eq. 4). 

Ss2 reaction with a,fi-epoxy ketones.6 The enolate 1 of 2,3-epoxycyclohexanone reacts with methyllithium to give, after acidic work-up, 2-methy -2-cyclohexenone (3), the product of SN2 addition. Reaction of 1 with lithium dimethyl cuprate on the other hand results in 6-methyl-2-cyclohexcnonc (2), the product of Sv2 addition. 

Vogel and Gunther8 have reported that 86 reacts with methyllithium to give a mixture of cis- and trans-6-methylcyclohexane-2,4-dienols (229) in which the cis trans ratio is higher than 9. Formation of the cis isomer as a major product in the reaction suggests that the reaction predominantly occurs through a cis 1,6-addition. Repetition of the reaction by Jeffrey et al,144 yielded only ct s-(229) in 67% yield. The reaction with dimethylmagnesium yielded a 37 63 mixture of cis- and trans-(229) in 26% yield. 

Methyloctaethylchlorin (64) was obtained from the oxochlorin 54 with methyllithium to give an alcohol, which was reduced with hydroiodic acid. Similarly, the isobacteriochlorins 9 and 65, which are models of siroheme and sirohydrochlorin, were obtained from dioxo derivatives 55 and 57 (80B1971). 

The neutral complex 244 (arene = benzene) has been found to react with nucleophiles such as hydride, hydroxide, and cyanide to give cyclohexadienyl derivatives, but they were too unstable to be isolated (7). The complex [Ru(C6H6)Cl(PMe3)2](PF6) (5) reacts with methyllithium to give... 

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. 

Condensation of the allylic alcohol 646 with methyl orthopropionate in butyric acid gave ester 647 which, after hydrolysis, was treated with methyllithium to give ketone 648. Fischer indole cyclization with poly-phosphoric acid of the phenylhydrazone of 648 gave the indole 649. The iV-oxide of 649 in trifluoroacetic anhydride at 0° gave in 92% yield the hexahydroellipticine 650, convertible with palladium-charcoal to 267 in 35% yield. The overall yield from 646 is on the order of 19% (Scheme 43). 

Surprisingly, the sulfur epimer 60 prepared from ( , )-2,4-hexadiene was found to be unreactive toward phenylmagnesium bromide. Compound 60-reacted with methyllithium to give 57, but the yield was poor. This result was rationalized by considering the conformations of adducts 54 versus 60. Adduct 54 exists as half-chair conformer 54A vide supra). 

The Wittig reaction is very useful. How else could we convert cyclohexanone into pure methylenecyclohexane We can use the reactions of this chapter to devise a different synthesis. Some thought might lead to a sequence in which cyclohexanone reacts with methyllithium to give, after hydrolysis, a tertiary alcohol. An acid-catalyzed elimination reaction would give some of the desired product, but there is no easy way to avoid the predominant formation of the imdesired isomer, 1-methylcy-... 

Hahdes of transition metals react with methyllithium to give methyl compounds. This reaction is alternatively afforded by organocopper compounds hke hthiumdialkylcuprates which are also known as Gilman reagents. These reagents are widely used for nucleophilic substitutions of epoxides, alkyl hahdes and for conjugate additions to a,p-unsaturated carbonyl compounds by methyl anion. 

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