Benzyl magnesium halides

A major problem with the sulfoxide synthesis using menthyl sulfmates is its failure to produce optically pure dialkyl sulfoxides. The prerequisite menthyl alkanesulfinates are oils which have resisted separation into the individual epimers. The menthyl phenyl methanesulfmates are an exception the R epimer is crystalline . One solution to this problem, at least for preparing methyl alkyl sulfoxides, was achieved using cholesteryl methanesulfmates (27) . Both epimers were crystalline and could be separated by fractional crystallization, although in poor yield. Treatment of the epimers with n-propyl, n-butyl, isobutyl, p-tolyl and benzyl magnesium halides yielded the respective methyl alkyl sulfoxides (28) in greater than 95% e.e. and in 32 to 53% yields. 

Yields of 2-substituted tetrahydrothiophenes (thiolanes) obtained by treating thietane 1-oxide with a two-molar excess of Grignard reagent, RCHjMgX, vary from 18-51%(R=H, CH3,Ph, o-CH3CgH)4. The best yields came from the benzyl-magnesium halides. 

The reverse system, reaction of (4-benzenesulfonylphenyl) allylsulfoxide (92) with benzyl-magnesium halide, led to the same result. 

The direct conversion of organometallics into cyanides (carbonitriles) is of considerable practical utility. Cyanogen chloride (Cl-CN) and dicyan (cyanogen, ethanedinitrile, NC-CN) have a proven track record for this type of transformation. They react with benzyllithium at the exocyclic benzylic position but with benzyl-magnesium halides at the ortho position, an Sjv2 site. ... 

Benzylmagnenhun halides constitute an interesting special caso, inasmuch as they give rise to small but significant proportions of rearrangement products. Treatment of ethylene oxide with benzyl-magnesium chloride, for example, gives a mixture of 3-phenyl- ] -propanol and 2 -p-tolylethanol (Eq. 820), as shown by the isolation of... 

Meerwein-Ponndorf-Verley type asymmetric reduction has also been accomplished with alkyloxy magnesium halides prepared from optically active alcohols. Optically active 2-octyloxy-2-d magnesium bromide reduced butyraldehyde to optically active n-butyl-1-d alcohol (Streitwieser, 1953). Reduction of benzaldehyde with 1-deuteroisobornyloxy magnesium halide produced optically active benzyl-l-d alcohol (Streitwieser and Wolfe, 1957 Streitwieser et al, 1959). 

The catalyst is not necessary either for the electrocarboxylation of aryl halides or various benzylic compounds when conducted in undivided cells and in the presence of a sacrificial anode of aluminum [105] or magnesium [8,106], Nevertheless both methods, i.e., catalysis and sacrificial anode, can be eventually associated in order to perform the electrocarboxylation of organic halides having functional groups which are not compatible with a direct electroreductive process. 

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