Structure of 19-acetylteuspinin, a new clerodane diterpenoid from the species Teucrium

Structure of a tricyclic lactone – an important intermediate for the total synthesis of dihydromevinolin

“…In all these molecules the fl-C is displaced from the lactone ring plane by about 0.6 A. The ?-lactone in C15H220 4 fits this pattern, the fl-C atom C(8a) is displaced from the best plane calculated for C(1), C(10), O(10), 0(80) and C (8) The same feature was observed in all the other ),-lactones associated with two six-membered rings (Eguren et al, 1981;Hirotsu et aL, 1975;Adinolfi et al, 1975a,b). The cyclohexane ring has a chair conformation which is slightly distorted from ideal geometry.…”

“…A survey of the saturated 7-1actones in a variety of molecules reveals a common conformation in which the C,~-CO-O-C v group is planar and the fl-C atom is at the flap of this envelope conformation. This usual arrangement is found for example in 19-acetylteuspinin (Eguren, Fayos & Perales, 1981), nagilactone A diacetate (Hirotsu, Higuchi, Shimada, Hayashi & Sakan, 1975), (+)-or (+)-trans-lfl-carboxy-8fl-hydroxy-1 a,4a,6fl-trimethyl-5-oxodecahydronaphthalene lactone (Adinolfi, Benedetti, Di Blasio & Pedone, 1975a,b). In all these molecules the fl-C is displaced from the lactone ring plane by about 0.6 A.…”

New neoclerodane diterpenoid containing an oxetane ring isolated from Teucrium chamaedrys. X-ray structure determination

“…JxA = 5 Hz), 2.95 (1 H, dd, Jab = 13.5 Hz, JBX = 8 Hz) and 2.41 (1 H, dd, Jax = 5 Hz) was assigned to the C-12 methyne and the C-ll methylene groups,3,14 and an AB system at 4.56 and 4.43 (Jab = 11 Hz) was attributed to the C-19 methylene grouping.3,15 A one-proton signal at 4.18 was assigned to the geminal proton of the secondary hydroxyl group of chamaedroxide, because it was downfield shifted ( 4.72) in the 1H NMR spectrum of the acetyl derivative 2. This signal showed that this alcohol function must be placed between two methylene groups, because it appeared as a broad multiplet in compounds 1 {W^m = 25 Hz) and 2 (16-line signal, W1/2 = 28 Hz). Thus, in a clerodane skeleton, only the C-2 position is likely for this hydroxyl group.…”