Sesquiterpenoids. Part XLVII. Structure, configuration, conformation, and thermal rearrangement of furanodienone, isofuranodienone, curzerenone, epicurzerenone, and pyrocurzerenone, sesquiterpenoids of Curcuma zedoaria

Abstract

Five new furo-sesquiterpenoids, furanodienone [(1E,4E)-8,12-epoxygermacra-1(10),4,7,11-tetraen-6-one](1), isofuranodienone [(1E,4Z)-8,12-epoxygermacra-1(10),4,7,11-tetraen-6-one](2), curzerenone [6,7-dihydro-5β-isopropenyl-3,6β-dimethyl-6-vinylbenzofuran-4(5H)-one](3), epicurzerenone [6,7-dihydro-5α-isopropenyl-3,6β-dimethyl-6-vinylbenzofuran-4(5H)-one](4), and pyrocurzerenone [6,7-dihydro-1,5,8-trimethylnaphtho-[2,1-b]furan)(15) have been isolated from the rhizomes of Curcurma zedoaria Roscoe, and their structures have been elucidated on the basis of chemical and spectroscopic evidence. The conformation of the ten-membered ring in (1) and (2) has been determined by use of the intramolecular internuclear Overhauser effect. Thermal rearrangements of these sesquiterpenoids are described.