¹H and ¹³C NMR assignments for lanostan‐3β‐ol derivatives: Revised assignments for lanosterol

Abstract

'H and l3C NMR assignments are presented for 30 oxygenated lanostane derivatives, including lanosterol, dihydrolanosterol, 7-ketolanosterol, agnosterol, 24,25epoxylanosterol, 8a,9a-epoxylanostan-3&01, three 15-oxygenated derivatives of lanost-7en-3~l, lanostane-3fl,7adiol, lanostane-3fl,9a-dioI and their acetates. These assignments, which were largely determined by a combination of DEPT, one-bond and long-range "C-'H chemical shift correlation and lanthanide-induced shift experiments, are not dependent on previously reported assignments, several of which were found to be incorrect. 'H and I3C acetylation shifts for lanostan-3b-ols were suficiently invariant among the sterols studied that they were useful for assigning carbons in rings A and B. The acetylation shifts reported for lanostan-3p-01~ were extended and partially revised.

Triterpenoids from Azorella trifurcata (Gaertn.) Pers and their effect against the enzyme acetylcholinesterase

“…These data showed agreement to a ∆ 9 lanostane skeleton with a hydroxyl group in ring A. 13 The compound 3 showed a cyclopropyl methylene (δ 0.31 and 0.53 d, J = 4.0 Hz) in the 1 H-NMR spectrum, along with seven methyl groups at δ 0.79, 0.86, 0.87 (6H), 0.95, 1.58 and 1.66, a proton at δ 3.26 (1H, m) and a proton signal at δ 5.10 (1H, t, J = 7.0 Hz), suggesting a cycloartane type of triterpenoid. These data are consistent with the compound 3.…”

“…These signals are characteristic of a ∆ 7,24 lanostane skeleton with a hydroxyl group in ring A. 13 The compound 5 was an acetate from 4.…”

“…These signals were characteristic of a ∆ 7 lanostane skeleton with a hydroxyl group in ring A. 13 The compound 2 was established as follows: The 1 H-NMR spectrum exhibited signals for eight methyl groups at δ 0.77, 0.81, 0.85 (6H), 0.92, 0.95, 0.98 and 1.12 ppm, along with a triplet at δ 5.16 (1H, t, J = 4.0) for an olefinic proton and a proton geminal at δ 3.20 (1H, dd, J = 10.9, 3.9) joined to a hydroxyl group. These data showed agreement to a ∆ 9 lanostane skeleton with a hydroxyl group in ring A.…”

Cell-based impedance spectroscopy for probing inhibitory effects of steroids and ergostane/lanosta-related compounds

“…25,26 Treatment of the epoxide (S1) with boron trifluroide-diethyl ether gave the diene (S2)i n excellent yield (94%).…”

“…Recrystallization of S3 from methanol gave white crystalline needles (0.300 g, 36%); mp 151-153 C; n max (KBr)/cm 5a-Lanost-8-ene-3,7,11-trione (S4). 12,25,26,31 Chromium trioxide (0.470 g) in 15 mL acetic acid (90%, v/v) was heated to 80 C and added to a stirring solution of dihydrolanosterol 27,28 (0.500 g) in 20 mL glacial acetic acid at 80 C. After 1 h at 80 C with stirring, the reaction mixture was cooled on an ice-bath, poured into water (40 mL) and extracted with chloroform (3 Â 40 mL). The combined organic extracts were washed with water (4 Â 30 mL), dried over MgSO 4 24(R)-5a-Lanost-8-ene-3,24,25-triol (S5a) and 24(S)-5a-lanost-8-ene-3,24,25-triol (S5b).…”