Robustaol A,a new acylph.lorogluoinol derivative,has been isolated from the leaves of medicinal plant Eucalyptus robusta Sm.(Myrtaoeae).The structure of robustaol A is proved to be 1 with the aid of UV,IR,NMR,MS spectral analyses,and through identification of its alkaline degradation products.The proposed structure of 1 has been confirmed by a four-step synthesis as shown in chart 2 of the Chinese text.Robustaol A showed antimalarial activity in mice.