A Novel Rearranged Abietane Diterpene From Coleus barbatus

Abstract

The new diterpene 9(10+20)-~-abieta-8,11,13-trien-l0 ,I 1.12-trio1 (I), has been isolated from the stems The rearranged 9(10*20)---abietane skeleton has received considerable attention in the last few years. Several new members of this group have been described', and the total syntheses of pisiferin' and barbatuso13 have been concluded. As a part of our continuous studies on the stems of the Labiate C&LY h t d J U I U 3 Bentham', we isolated diterpene 1 as a yellowish gum that turned rapidly to reddish-brown on standing. General spectral data6 indicated the presence of an isopropyl moiety linked to a pentasubstituted aromatic ring, of two tertiary methyl groups and of h droxyl functions Ace lation of 1 furnished the more stable diacetate 2 that still displayed OH absorption in IR, indicating a tertiary OH group. The I3C NMR spectrum of 2 Fable 1) corroborated all cited structural features and proved the phenolic nature of both of Colt.us hurbufus Bentham and its structure determined P rom spectral data and hemisynthesis.

Efficient Synthesis of Icetexane Diterpenes and Apoptosis Inducing Effect by Upregulating BiP-ATF4-CHOP Axis in Colorectal Cells

“…[α]­25 D −32.0 ( c 0.2, CHCl 3 ); 1 H NMR (400 MHz, CDCl 3 ): δ 7.00 (s, 1H), 3.33–3.23 (m, 2H), 3.19 (s, 1H), 2.95 (sept, J = 6.9 Hz, 1H), 2.71–2.64 (m, 1H), 2.41 (d, J = 17.4 Hz, 1H), 2.32 (s, 3H), 2.29 (s, 3H), 1.99–1.85 (m, 2H), 1.80–1.72 (m, 1H), 1.71–1.68 (m, 1H), 1.65 (s, 1H), 1.49–1.39 (m, 1H), 1.24 (d, J = 6.9 Hz, 3H), 1.22 (d, J = 6.9 Hz, 3H), 0.91 (m, 1H), 0.87 (s, 3H), 0.76 (s, 3H); 13 C NMR (101 MHz, CDCl 3 ): δ 168.8, 168.1, 140.8, 139.3, 139.2, 138.2, 128.1, 125.0, 60.3, 59.3, 41.8, 37.9, 32.9, 30.3, 28.7, 28.45, 27.5, 26.6, 25.7, 23.1, 22.8, 22.1, 20.4, 20.4; HRESIMS ( m / z ): calcd for C 24 H 36 O 5 N [M + NH 4 ] + , 418.2593, found 418.2598. The spectral data of 5 are identical to that of the previous report …”

“…The crude product was purified with silica gel chromatography (petroleum ether: EtOAc = 7:1) to give 5 as a colorless film (696 mg, 87% yield). [α]25 D −32.0 (c 0.2, CHCl 3 ); 1 H NMR (400 MHz, CDCl 3 ): δ 7.00 (s, 1H), 3.33−3.23 (m, 2H), 3.19 (s, 1H), 2.95 (sept, J = 6.9 Hz, 1H), 2.71−2.64 (m, 1H), 2.41 (d, J = 17.4 Hz, 1H), 2.32 (s, 3H), 2.29 (s, 3H), 1.99−1.85 (m, 2H), 1.80−1.72 (m, 1H), 1.71−1.68 (m, 1H), 1.65 (s, 1H), 1.49−1.39 (m, 1H), 1.24 (d, J = 6.9 Hz, 3H), 1.22 (d, J = 6.9 Hz, 3H), 0.91 (m, 1H), 0.87 (s, 3H), 0.76 (s, 3H); 13 37 Procedures for the Preparation of Przewalskin D-11,12diacetate (6). To a solution of 5 (48 mg, 0.12 mmol) in tetramethyldiamidophosphoric acid chloride (0.5 mL), a drop of H 2 O was added.…”

Diverse Types of Diterpenoids with an Aromatized C Ring from the Twigs of Podocarpus imbricatus

“…The relative configuration of 14 with the relative orientation of HO-10 and H-5 was assigned by comparison of its 13 C NMR data with corresponding signals in related compounds. The chemical shift of C-5 (δ C 58.4) in 14 resembled that of pisiferanol (C-5, δ C 58.4) rather than its C-10 synthetic epimer (C-5, δ C 53.4) . The HO-10 and H-5 in 14 were thus determined as trans -configured, and it was in congruence with the downfield-shifted C-5 without any steric effect from the HO-10 group.…”

“…9 The HMBC correlations (Figure 5) from 2 and 3) for a tetrasubstituted aromatic ring and a keto-carbonyl group accounted for five out of the seven degrees of unsaturation, consistent with two additional rings in the structure. Compound 14 was assigned as an analogue of pisiferanol, 19 an icetexane-type diterpenoid, namely having a rearranged 9(10 → 20)-abeo-abietane skeleton, based on the observed NMR resonances for an isopropyl group, two methyls, five methylenes, one methine, one oxygenated tertiary carbon, and one quaternary carbon. When compared to pisiferanol, compound 14 was shown to contain an additional ketocarbonyl group at C-3, as deduced by the HMBC correlations (Figure 5) from H-1, H-2, and 19 The HO-10 and H-5 in 14 were thus determined as trans-configured, and it was in congruence with the downfieldshifted C-5 without any steric effect from the HO-10 group.…”

Structure, biosynthetic relationships and chemical synthesis of the icetexane diterpenoids

“…Salvicanol (13) was originally isolated from the roots of Salvia canariensis, 28 and was later found in the roots of Salvia mellifera in a study which also established the absolute configuration by X-ray crystallography. 29 The closely related compound demethylsalvicanol (14) was found in C. barbatus, 30 while isosalvicanol (15) was identified in the aerial parts of Lepechinia meyeni. 31 The unique icetexane dimer grandione was isolated from the wood of the coniferous evergreen tree Torreya grandis Fort.…”