Methyl 2,3,4-tri-O-benzoyl-6-O-[(4-methylphenyl)sulfonyl]-alpha-D-mannopyranoside is a reagent in the partial tosylation of methyl α-D-mannopyranoside, and also a useful reagent for the in vitro investigation of potential antiproliferative monosaccharide-D-secoestrone bioconjugates.