Phenoxymagnesium bromide

Table 5.1 Ortho-regioselective acylation of phenoxymagnesium bromides with acyl chlorides...

Acetals have been employed to derive 1,1-bis(2-hydroxyphenyl)alkanes. In this way propanal diethylacetal added to phenoxymagnesium bromide, prepared from phenol and ethylmagnesium bromide, gave 1,1-bis(2-hydroxy-phenyl)propane in 70% yield after refluxing for 24 hours (ref. 10). The enolic character of the phenoxy compound favours nucleophilic 2-substitution. 

A further example of the regiospecific synthetic utility of phenoxy magnesiumbromide is illustrated by the foltowing reaction. Phenoxymagnesium bromide in toluene, prepared in the usual way from phenol and ethylmagnesium bromide in toluene, treated dropwise with oxalyl chloride in toluene over 20 mins, and then reacted at ambient temperature for 7 hours, gave, after work-up by acidification, 2-hydroxyphenylglyoxylic acid in 44% yield (ref.57). 

Reaction of CeHsOMgBr with HCHO. Phenoxymagnesium bromide (I) reacts with formaldehyde in benzene solution to form 2 and 3 through an intermediate o-quinone methide (a). In the presence of stoichiometric amounts of... 

Also obtained by a selective one-step synthesis from phenoxymagnesium bromide (1 mol) and anhydrous monomeric glyoxal (1 mol) in boiling benzene for 20 h (24%) [5059]. 

The alkylation of phenoxymagnesium halides with Ai-(ferf-butoxycarbonyl)-a-amino aldehydes also gives excellent diastereoselection. 2-ferf-Butylphenoxymagnesium bromide, for example, has been found to react with Ai-(ferf-butoxycarbonyl)-L-prolinal to give exclusively the syn diastereomer regio- and stereoselectively (equation 27) . ... 

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