Reactivity of γ-benzyloxyallyltins with cyclohexylidene glyceraldehydes

Benzyloxyallyltributyltins were obtained in 50–80% yield by SN2′ reaction of alkyl-cyanocuprates with 3,3-dibenzyloxy-1-tributylstannylprop-1-ene in the presence of boron trifluoride. They reacted with cyclohexylidene glyceraldehyde in the presence of different Lewis acids and the obtained diastereomeric adducts were unambiguously identified after an ozonolysis/deprotection sequence by comparison with authentic aldopentoses. The mechanisms are briefly discussed as well as the relationship of the configuration of the reagents to the selectivity of the allylstannation reaction.