A process for the preparation of etoposides

The invention relates to a process for producing a beta-glucopyranose derivative of the formula I in which R and R are H or an acyl protective group and R is H, benzyl or a radical of the formula II where R is H or a benzyloxycarbonyl or chloroacetyl protective group and A is C1-C4-alkyl, characterised in that a benzyl glucopyranoside of the formula I in which R and R are an acyl protective group, R is a benzyl protective group and A is C1-C4-alkyl, is subjected to hydrogenolysis in the presence of a hydrogenation catalyst and of an organic solvent to eliminate the benzyl group and to form a glucopyranose derivative which is in the beta-hydroxy form and has the formula I, in which R , R and A have retained their meaning, and R is a hydrogen atom, subsequently this glycosidation component is reacted with an epi-podophyllotoxin derivative of the formula III in which R is benzyloxycarbonyl or chloroacetyl protective group, in the presence of a promoter such as BF3xether or of a tri-(C1-C4) alkylsilyl trifluoromethanesulphonate and of an organic solvent, optionally in the presence of a desiccant at -30 DEG C to 0 DEG C, resulting in a beta-glycoside of the formula I in which R , R , R and A have retained their meaning and R is a radical of the formula II, and the product which is formed is subjected to hydrogenolysis to eliminate the benzyloxycarbonyl protective group, and the acyl protective group is eliminated using basic ion exchangers in the presence of a polar solvent, resulting in a product of the formula I in which R and R are hydrogen, R is a radical of the formula II with R equal to hydrogen and A is C1-C4-alkyl.