Benzylmagnesium Bromide is mainly used for the formation of diastereomeric o-toluylmethanol via a format reaction. Moreover, benzylmagnesium bromide only generates o-tolylmethanol when used in excess or at higher temperatures[1].
Benzylmagnesium bromide can be prepared by reacting benzyl bromide with magnesium powder in an anhydrous solvent (such as THF or diethyl ether); the reaction must be carried out under an inert atmosphere (such as nitrogen or argon) to prevent contact with air and moisture.
[1] MARO\VS BELLA. Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement.[J]. Beilstein Journal of Organic Chemistry, 2014: 1942-1950. DOI:10.3762/bjoc.10.202.