Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement
Journal article, 2014

The Grignard reaction of 2,3-O-isopropylidene-alpha-D-lyxo-pentodialdo-1,4-furanoside and benzylmagnesium chloride (or bromide) afforded a non-separable mixture of diastereomeric benzyl carbinols and diastereomeric o-tolyl carbinols. The latter resulted from an unexpected benzyl to o-tolyl rearrangement. The proportion of benzyl versus o-tolyl derivatives depended on the reaction conditions. Benzylmagnesium chloride afforded predominantly o-tolyl carbinols while the application of benzylmagnesium bromide led preferably to the o-tolyl carbinols only when used in excess or at higher temperatures. The structures of the benzyl and o-tolyl derivatives were confirmed unambiguously by NMR spectral data and X-ray crystallographic analysis of their 5-ketone analogues obtained by oxidation of the corresponding mixture of diastereomeric carbinols. A possible mechanism for the Grignard reaction leading to the benzyl -> o-tolyl rearrangement is also proposed.

X-ray crystallography


Grignard reaction

benzyl versus o-tolyl




M. Bella

Slovak Academy of Sciences

Bohumil Steiner

Slovak Academy of Sciences

Vratislav Langer

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

Miroslav Koos

Slovak Academy of Sciences

Beilstein Journal of Organic Chemistry

1860-5397 (ISSN)

Vol. 10 1942-1950

Subject Categories

Chemical Sciences



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