To piscicldal solidagolactones [IV, V, VII and VIII (l-4, cisclerodane diterpenes)] isolated from Solidago altlsslma, a non-steroidaTconformatlon was assigned on the basis of chemical and physiccchemical evidence. 13c NMR chemical shifts of methyl groups proved useful for determining stereochemistry of the A/B ring junction in clerodanes. For clerodanes having an epoxide, 1R NMR data and the Tori equation were useful for assigning the epoxide configuration. Cremer's puckering parameters were used to express the conformation of the solidagolactones. Iotrodmctial Some erroneous assignments have been reported for absolute wnfigurationsl, stereochemistry of the A/B ring junction2 and epoxide configurations3 in clerodane diterpenes. We have isolated solidaoglactones IV(l), V(2), VII(S) and VIII(I) (all cis-clerodane diterpenes) from Solidago altlssima L. (&positae) as pisclcidal constituents, and determined their absolute configurations, as reported in short communications3r4. In j this paper, we wish to describe structure determination of l-4 in detail, and also to demonstrate the usefulness of 13C NMR chemical shifts of methyl groups, Cremer's puckering parameters and one of the Tori equations for determining stereochemistry of A/B ring junction, precise molecular conformation and epoxide configuration, respectively. The epoxide coni'igurations of several cis-clerodanes are corrected in this study. -By monitoring the piscicidal activity for killiflsh, we Isolated plsclcidal compounds 1-4 from the methanol (Mm) extract of S_ altissima by column chromatographics and recrystallizatioo (l-3) (Scheme 1). Compounds l-3 were the known solidagolactones IV, V and VI12, respectively. 1~ NMR spectrum of 4, a new compound named as solidagolactone VIII, quite resembled to that of 3 except for protons on the C6 substituent 161.81 (3H, dm, 2~6.8 Hz, 1.89 (3H, m) and 6.90 (la. qq, 511.2 and 6.8 Hz)]. which was assigned to tygloyloxyl moiety. The C6 protons (H6) showed a triplet in 1 (1S3.71) or double doublets in 3 (65.44) and 4 (65.40) signals, all of which possessing small 2 values (2.50-2.80 Hz). This means that the H6 in these compounds is in equatorial position. With diisobutylaluminum hydride (DIBAL) lo tetrahydrofuran (THF) (-35Β°+-200C, 3.5 hr), 3 and 4 converted into furano-compounds 5 and 6, respectively, both of which showed the presence of a B-substituted furan rlng in IR (Vmax 880 cm-l) and lH NKR [66.25 (lH, m), 7.2l(lH, m) and 7.35 (la, t, 511.5 Hz)] spectra. Both 5 and 6 gave Identical Anal. Calcd.