Epoxide with methyllithium

The 1 la-methyI-9, lly5-epoxide (41) is the sole product of the reaction of the 9a-fluoro-11-ketone (40) with methyllithium. ... 

The 1,2-carbonyl transposition takes place through the enJo-epoxide 18 easily prepared through the tosylhydrazone 16, followed by regioselective cleavage to the less substituted double bond (17) with 2 equivalents of methyllithium [4] and epoxidation with MCPBA in chloroform from the more accesible convex face of the decalin system. 

Reaction of the epoxide of 1-butene with methyllithium gives 3-pentanol in 90% yield. In contrast, methylmagnesium bromide under similar conditions gives the array of products shown below. Explain the difference in the reactivity of the two organomet-allic compounds toward this epoxide. 

In a related process, D-allal derivative 40 was first obtained [143] from the alio epoxide 39 by treatment with methyllithium. Subsequently, it was demonstrated that 2-iodo-D-altroside [144] 41 and its deprotected analog [145] 42 gave even higher yields of the allal (40 and 43, respectively) when treated with an excess of alkyllithium (O Scheme 13). Incidentally, benzylidene derivative 40 could not be deprotected to 43 without decomposition. 

Danishefsky prepared the furanophane 184 and converted it to hydropyrone 185 through a directed epoxidation with DMDO. Diastereoselective addition of methyllithium was followed by an acid catalyzed isomerization to the furanoside 186. Vinylogous aldol addition of a silyloxy furan to an imine gave 189 that was easily isomerized to the azacycle 190. Another general strategy to prepare pyran derivatives is a cycloaddition/fragmentation route involving an oxabicyclo[3.2.1]octane intermediate (Scheme 24). 

The intermediate alkenylalane can be used in several ways. If a protiolytic work-up is used, then formation of the corresponding (Z)-alkene is observed (eq 27). Treatment of the alkenylalane with Methyllithium affords an ate complex which is nucleophilic and reacts with a variety of electrophiles, e.g. alkyl halides, CO2, Mel, epoxides, tosylates, aldehydes, and ketones (eq 28). ... 

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. 

The 16a,l7a-epoxide (12) can be made to react with methylmagnesium bromide or methyllithium as well as phenyllithium to yield (13a) and (13b), respectively, after ketal cleavage. 

Cyclopentene oxide is reported to react smoothly with methyl lithium,but higher alkyl Lithiums have not been examined with thia epoxide until now. Methyllithium likewise condenses readily with. 1,3,3-trichloro-1,2-epoxypropane487 to give the corresponding terminal addition product (Eq. 803). 

Diastereoselective reduction of chiral -keto sulfoxides (11,291-292). Chiral p-keto sulfoxides 1, prepared by reaction of p-(tolylsulfinyl)methyllithium with esters, are reduced by DIBAH in THF diastereoselectively to (R,S)-2. In the presence of ZnCl2, the opposite diastereoselectivity obtains. The paper includes a new method for conversion of these p-hydroxy sulfoxides into chiral epoxides.1... 

In reaction (28) y-elimination of LiCl with the formation of an epoxide is obviously faster than P-elimination of Me3SiOLi (Peterson-olefination). Seyferth and his collaborators34) found that this reaction takes place when bis(trimethylsilyl)bromo-methyllithium is reacted with carbonyl compounds, albeit not stereoselectively (Eq. (30)). In contrast, thermal dehydrohalogenation of 1,1-dichloro-l-phenyl-dimethylsilyl-alkanes furnishes Z-olefins only (Eq. (31)) according to the results of Larson et al. 35) ... 

A further interesting example is the use of l,l-di(phenylthio)med)yllithium to open an epoxide followed by a Grob fragmentation process as shown in Scheme 56 (entry b). The reaction of 1,1-di-(thio)methyllithium with epoxides has also been used - in the one-pot synthesis of l,l-di(thio)cyclopropanes involving an intramolecular cyclization of the 7-tosyloxydi(phenylthio)alkylli-thium. This intramolecular alkylation reaction proceeds even more efficiently than its intermolecular version, and allows the synthesis of a large variety of l,l-di(thio)cyclopTDpanes from 3-chloro- and 3-phenylthio-l,l-di(thio)alkanes and n-butyllithium in THF (Scheme 57 and Scheme 58). 

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