Modification of chemical reactivity upon cyclodextrin encapsulation: Asymmetric bromination of chalcone and benzylideneacetone

Article abstract of DOI:10.1016/S0040-4020(01)85274-1

Asymmetric bromination of chalcone and benzylideneacetone (trans-isomers) in crystalline β-cyclodextrin complex was studied. While bromination of chalcone in the absence of β-cyclodextrin yields erythro-dibromide, bromination of β-cyclodextrin-chalcone complex results in the formation of a mixture of erythro- and threo-dibromides respectively in the ratio 80:20. Complexation does not induce any variation in the bromination pattern in the case of trans-benzylideneacetone. These observations have been accounted for in terms of different conformations of the enones in the β-cyclodextrin-enone complexes. Complex formation between the substrate and cyclodextrin has been confirmed by various physical methods.