REACTION DE TRANSACETALISATION PAR LE DIMETHOXYMETHANE SYNTHESE DE O-METHYLENEACETAL DE DERIVES DU D(+)GLUCOSE

Article abstract of DOI:10.1016/S0040-4020(01)81020-6

The acid catalyzed and LiBr assisted transacetalization from dimethoxymethane applied to α and β glucosides allows the selective methylenation of the -4 and -6 hydroxyl functions.The α anomer leads to the compound 4 , but under the same conditions, the β anomer leads to a mixture of the methylene acetal protected carbohydrates 4 and 5.Glucose, under our transacetalization conditions, affords, after in-situ O-glycosidation and protection, the same compounds 4 and 5.The classical methylenation using formol/HCl with glucose and glucosides, does not lead to the expected products but to the same glucofuranoside compound 6 which results from a O-demethylation of the glucoside.