抄録
Three new furanoeremophilanes were isolated from Farfugium japonicum Kitam., and their structures were determined as 6, 7 and 8. Two new furanoeremophilanes isolated from Farfugium hiberniflorum were shown to be represented by 9 and 10. Conformations of 6, 7, 11 and 15 are discussed. Furanoeremophilane-6β,10β-diol (1) was treated with POCl_3 in pyridine to give 4, 5 and 20. Absolute configurations of 1 and 4 were determined as 1a and 4a, respectively; this shows a retention of configuration at C-9 of 4a, excluding the route (D→G→4b). Cyclohexadienyl cation D (delocalized) initially formed rearranges into 4a via E and F. Formation of 5 and 20 from D can also be interpreted as shown in H.
