Seco-prezizaane Sesquiterpene Research Articles

Investigation on seco-prezizaane sesquiterpenes from fruits of Illicium lanceolatum and their neuroprotection activity

Ten seco-prezizaane sesquiterpenes were isolated from the water-soluble fraction of the fruit of Illicium lanceolatum using the combined methods of silica gel column chromatography,Sephadex LH-20 column chromatography,and RP-preparative HPLC. They were elucidated as majusanol E( 1),2α-hydroxycycloparviflorolide( 2),2β-hydroxy-3,6-dedioxypseudoanisatin( 3),majusanol A( 4),merrillianone( 5),cycloparvifloralone( 6),3α-hydroxycycloparvifloralone( 7),1,2-dehydrocycloparvifloralone( 8),henrylactone C( 9),and( 11) 7,14-ortholactone-3α-hydroxyfloridanolide( 10) according to the NMR data. All compounds were obtained from this plant for the first time. Neuroprotection activity,anti-Coxsackie B3 virus,and anti-H3 N2 virus experiments were carried out to test their bioactivities. The bioassay results showed that compounds 1,4,6,7,9 and 10 displayed weak protective effects of the damage of nerve SH-SY5 Y cell induced by monosodium glutamate.

Contemporary Synthetic Strategies toward seco-Prezizaane Sesquiterpenes from Illicium Species.

Since the elucidation of the structure of anisatin in the late 1960s, sesquiterpene lactones from various Illicium species of plants have captivated synthetic chemists worldwide, resulting in a large body of synthetic work. In particular, Illicium sesquiterpenes containing the seco-prezizaane carbon framework have seen immense interest in recent years owing to desirable structural and medicinal attributes. This synopsis will focus on recently developed synthetic strategies to access these compact, highly oxidized terpenoids.

Formal Total Synthesis of (-)-Jiadifenolide and Synthetic Studies toward seco-Prezizaane-Type Sesquiterpenes.

Synthetic studies toward highly oxygenated seco-prezizaane sesquiterpenes are reported, which culminated in a formal total synthesis of the neurotrophic agent (-)-jiadifenolide. For the construction of the tricyclic core structure, an unusual intramolecular and diastereoselective Nozaki-Hiyama-Kishi reaction involving a ketone as electrophilic coupling partner was developed. In addition, synthetic approaches toward the related natural product (2R)-hydroxy-norneomajucin, featuring a Mn-mediated radical cyclization for the tricycle assembly and a regioselective OH-directed C-H activation are presented.

Synthesis of Neurotrophic Seco-prezizaane Sesquiterpenes (1R,10S)-2-Oxo-3,4-dehydroneomajucin, (2S)-Hydroxy-3,4-dehydroneomajucin, and (-)-Jiadifenin.

An asymmetric approach to the synthesis of neurotrophic seco-prezizaane sesquiterpenes is described that is based on the strategic application of a hydroxyl-directed metallacycle-mediated [2 + 2 + 2] annulation and an intramolecular radical cyclization cascade. Targets prepared are among the most potent members of the natural product class and include (1R,10S)-2-oxo-3,4-dehydroneomajucin, (2S)-hydroxy-3,4-dehydroneomajucin, and (-)-jiadifenin. In addition to representing the first application of the alkoxide-directed metallacycle-mediated hydrindane-forming annulation reaction in natural product synthesis and the first total synthesis of (2S)-hydroxy-3,4-dehydroneomajucin, these pursuits have resulted in the elucidation of a complex radical cascade process for installation of the C5 quaternary center common to the natural product class.

Protecting-Group-Free Total Synthesis of (−)-Jiadifenolide: Development of a [4 + 1] Annulation toward Multisubstituted Tetrahydrofurans

A concise, protecting-group-free total synthesis of (-)-jiadifenolide, a synthetically challenging seco-prezizaane sesquiterpene with potent neurotrophic activity, is reported. The convergent route features a SmI2/H2O-mediated stereoselective reductive cyclization, an unprecedented formal [4 + 1] annulative tetrahydrofuran-forming reaction and programmed redox manipulations. The newly developed annulation of β-hydroxy aldehydes or ketones with lithium trimethylsilyldiazomethane provides access to a diverse array of multisubstituted tetrahydrofurans. The synthetic jiadifenolide exhibited weak cytotoxicity against five human cancer cell lines.

Sesquiterpenes from the roots of Illicium oligandrum

Two new sesquiterpenes, oligandrin (1) and oligandric acid (2), together with three analogues, tashironin A (3), tashironin (4), and oplodiol (5), were isolated from the roots of Illicium oligandrum. The structures of new compounds were determined based on 1D and 2D NMR experiments and X-ray diffraction. Compound 1 represents a presumed biosynthetic precursor of seco-prezizaane sesquiterpenes which consists of a novel 6/6/5 tricarbocyclic skeleton. Compound 2 is the first example of chamipinene-type sesquiterpene possessing a 6/4/6 tricyclic system from the genus Illicium. Compounds 1–5 were evaluated in vitro for their activity against coxsackie virus B3 (CVB3), influenza virus A/Hanfang/359/95 (H3N2), and influenza virus A/FM/1/47 (H1N1). Compound 1 showed selective antiviral activity against CVB3 with IC50 value of 11.11 μM.

An Approach to seco-Prezizaane Sesquiterpenoids: Enantioselective Total Synthesis of (+)-1S-Minwanenone

A strategy of general applicability toward seco-prezizaane sesquiterpenes, from a chiral, tricyclic synthon, readily available via an enzymatic resolution step from the Diels-Alder adduct of cyclopentadiene and p-benzoquinone, has been devised. Our approach enables harnessing of the stereochemical proclivities of the norbornyl system to install the desired stereochemistry at the key stereogenic centers. Recourse to an interesting stratagem to realign a stereochemical divergence into stereoreconvergence forms the cornerstone of our successful approach. The first total synthesis of (+)-1S-minwanenone, a prototypical member of seco-prezizaane subclass, has been accomplished.

Total synthesis of the novel seco-prezizaane sesquiterpenoid (+)-1 S-minwanenone

The first total synthesis of (+)-1 S-minwanenone, an archetypical seco-prezizaane sesquiterpene, has been accomplished from a readily available chiral endo-tricyclic synthon following a flexible strategy.

Secoprezizaane Sesquiterpene Lactones from Illicium micranthum

AbstractThree new secoprezizaane sesquiterpene lactones, (1R,2S)‐1,2‐epoxyneomajucin (1), (2R)‐2‐hydroxyneomajucin (2), and (2R)‐2‐hydroxymajucin (3), along with six known compounds (4–9), were isolated from the poisonous shrub Illicium micranthum. Their structures were established by in‐depth analyses of spectroscopic and mass‐spectrometric data.

New allo-cedrane type sesquiterpene hemiketals and further sesquiterpene lactones from fruits of Illicium floridanum.

Three new tetracyclic sesquiterpene hemiketals possessing the very rare allo-cedrane carbon skeleton, debenzoyl-7-deoxo-1 alpha,7 alpha-dihydroxytashironin, debenzoyl-7-deoxo-7 alpha-hydroxytashironin, and debenzoyl-7-deoxo-7 alpha-hydroxy-3-oxotashironin (1--3), were isolated from the fruits of Illicium floridanum ELLIS (American Star Anise, Star bush). Their structures were elucidated by mass and NMR spectroscopic analyses. The molecular structure of 1, including absolute stereochemistry, was determined by single-crystal X-ray diffraction of its monohydrate. Only one compound of this type, tashironin, has previously been isolated from Illicium tashiroi. Furthermore, a new sesquiterpene lactone of the seco-prezizaane type, 3,4-anhydro-13,14-dihydroxyfloridanolide (4), and the known anislactone B (5) were isolated. The occurrence of further allo-cedrane sesquiterpenes in another Illicium species confirms the hypothesis of previous authors that this type of compound is a biogenetic precursor of the typical seco-prezizaane sesquiterpene lactones found in this genus. Moreover, regarding their co-occurrence with anislactone B as reported here, they may also be considered precursors for the anislactone skeletal type.

Seco-Prezizaane-type sesquiterpenes from Illicium merrillianum

Four seco-prezizaane sesquiterpene lactones, 14- O- n-butyrylfloridanolide, 3,4-dehydrofloridanolide, 3,6-dideoxy-10-hydroxypseudoanisatin, and 2- O- n-butyrylpseudomajucin were isolated from the pericarps of Illicium merrillianum. Their structures were determined by spectroscopic methods.

Novel seco-prezizaane sesquiterpenes from north american illicium species

Three novel seco-prezizaane sesquiterpenes (1-3) were isolated from leaves of Illicium parviflorum (swamp star anise, yellow star anise), a species occurring endemically in central Florida. Compound 1, named cycloparvifloralone, possesses a hitherto unknown ring system with a cagelike acetal/hemiketal structure. Lactones 2 (cycloparviflorolide) and 3 (parviflorolide) which were obtained as an inseparable mixture, coexist in a hemiketal/keto equilibrium. It could be shown that a 4,7-hemiketal (4) occurs in an analogous fashion to pseudoanisatin 5, a known constituent of other Illicium species. From the fruits of Illiciumfloridanum the novel ortholactone 6 was isolated. The structures of the new compounds were elucidated by interpretation of their 1D and 2D homo- and heteronuclear NMR spectroscopic data. The modes of cyclization observed in 1, 2, 4, and 6 have not been described previously, and a biogenetic sequence is proposed for these compounds and further seco-prezizaane sesquiterpenes.